Stability and interaction in the housing market: Log‐linear and vacancy chain models

Although one may find some examples of vacancy chain analysis in which the chain is actually traced, most researchers use Markov vacancy chain models now, because these are less demanding in their data requirements. In constructing this kind of model a number of assumptions have to be made, viz. regarding homogeneity, stationarity and markovicity. Before applying these models the validity of these assumptions will have to be clarified. In this contribution we will present an empirical test for some of these assumptions, using a log‐linear approach. We will also use the log‐linear model to measure the interaction among various housing submarkets. It will be shown that three types of interaction can be distinguished and measured—segmentation, dominance and substitution. Although these aspects are crucial to the study of vacancy chains, they cannot be derived directly from the results of the vacancy chain models.     

Urban aesthetics and the discovery of the urban fabric in turn‐of‐the‐century Germany

Approaches to planning that developed in the later nineteenth century in Germany (and in Europe generally) were challenged on aesthetic grounds at the end of the century by Camillo Sitte and others. By the turn of the century, practitioners of planning had embraced Sitte's views on a number of matters. Among the changes that occurred were an end to the disencumbering of monumental buildings and a greatly expanded interest in historic preservation. This was not simply a matter of aesthetics gaining more influence over planning practice, however. Sitte's desire to develop systematically the aesthetic dimension of planning was shared by earlier theorists, notably Hermann Maertens, who endorsed many of the practices Sitte rejected. Ultimately, the compatibility of the new aesthetics with more practical needs was crucial to its acceptance. The new interest in historical models reflected an understanding of urban form that enabled planners to reconcile their aesthetic goals with other needs.     

Impact of physico‐chemical parameters on the microbial population and its nature in a major retting zone of Kerala

As part of an environmental abatement programme, through the application of bioremediation in the retting zones of Kerala, a microbiological survey was conducted during March 1999 in the Kadinamkulam kayal, a major retting zone in Kerala. Some selected physico‐chemical parameters were also analysed to assess the water quality in the context of retting activity. Comparatively low dissolved oxygen content coupled with high hydrogen sulphide observed at Stations 1 and 2 can be attributed to retting. Salinity distribution is of the mixohaline nature. Pseudomonas sp., E. coli and other coliform groups were found to be present in the area. Of these the most dominant was Pseudomonas sp. and hence its nature and plasmid profile were also studied. The study indicates an environmental degradation in the area, and the possibility of hotspots of pollution in the backwater biotopes in the State.     

Geosynthetics for waterways and flood protection structures – Controlling the interaction of water and soil

The interaction of water and soil has been both a blessing and a curse in all times within living memory. Water is the origin of life but is also threatening life when appearing unboundedly. Therefore mankind has always worked hard to benefit from water resources on one hand and to deal with the threat of flooding on the other hand. For both, to protect the land and to allow for beneficial uses like irrigation or navigation, often special measures are necessary to keep the water within certain bounds. Structures to achieve a permanently stable situation like irrigation and navigational canals, river training or flood protection measures need suitable material, carefully thought out design and accurate execution. Often a decision has to be made among competitive approaches to optimize such structures. In many cases, geosynthetics can support or improve the functionality and sometimes only with geosynthetics the desired result can be achieved.     

Phosphorus immobilisation in Al‐drinking water treatment sludge (Al‐DWTS) and soil under laboratory conditions

This study assessed the potential reuse of an aluminium coagulated drinking water treatment sludge (Al‐DWTS) as a main substrate in constructed wetland to replace soil for the treatment of P‐enriched wastewater. The adsorption isotherm and kinetics of phosphorus (P) removal from high‐P solution by Al‐DWTS and a local soil from Bailieborough, Ireland, were studied and compared. The P adsorption process was examined as a function of contact time, initial P concentration, pH and temperature. Data of P adsorption were well fitted to the Langmuir and the Freundlich isotherms but the Freundlich isotherm had a higher correlation coefficient. The P adsorption capacity on the Al‐DWTS and the soil tended to increase with an increase in temperature. The maximum P adsorption capacity of the Al‐DWTS and the soil was 39.4 mg P mg^?1 and 9.5 mg P mg^?1, respectively, at conditions of pH of 4.0 and temperature of 23°C. Kinetics studies show that adsorption in both cases followed pseudo‐second‐order kinetics. The fact that the Al‐DWTS exhibited a significantly higher P adsorption capacity at high P solution compared with the soil suggests that Al‐DWTS can be a ‘novel‐waste’ bioadsorbent with promising application in wastewater treatment engineering, such as constructed wetland systems.     

Costs‐in‐use

This paper from the Head of the Costs‐in‐use Section at the UK Building Research Establishment suggests that constraints on the wide application of the concept in the UK derive partly from existing practices and procedures and partly from a misunderstanding of the concept's relevance. The term ‘costs‐in‐use’ would be better defined as ‘costs‐of‐defined‐performance'; and because of the fragmentary nature of the industry and unsatisfactory existing procedures, independent research is needed to clarify the true scope of this appraisal technique in the context of building procurement.     

Changes in the environmental pollution in the Calcutta‐Hooghlyside industrial strip of India

Changes in the environmental perception of people of the Calcutta‐Hooghlyside industrial belt are discussed. Residents of the area are becoming increasingly aware of air and water pollution. A positive correlation exists between the frequency of their perception of air and water pollution problems and the actual level of pollution in the area.     

Investigation of geotextile–soil interaction under a cyclic vertical load using the discrete element method

Geotextiles are often used in roadway construction as separation, filtration, and reinforcement. Their performance as reinforcement in geotextile-reinforced bases depends on geotextile–soil interaction. This paper investigates the geotextile–soil interaction under a cyclic wheel load using the Discrete Element Method (DEM). In this study, soil was modeled as unbonded particles using the linear contact stiffness model, and the geotextile was modeled as bonded particles. The micro-parameters of the soil and the geotextile were determined using biaxial tests and a tensile test, respectively. The influence of the placement depth and the stiffness of the geotextile on the performance of the reinforced base was investigated. The DEM results show that the depth of the geotextile significantly affected the degree of interaction between the geotextile and the soil. Under the applied cyclic vertical load, the geotextile developed a low tensile strain. The effect of the stiffness of the geotextile on the deformation was more significant when the geotextile was placed at a shallower location than when placed at a deeper location.     

Monitoring of bacterial community changes in leachate and wetland soil using T‐RFLP analysis

The removal of toxic materials in municipal solid waste (MSW) can be carried out within both bioreactors and constructed wetlands. In this study, the microbial community was analysed to monitor populations related to leachate. Wetland soil samples of two landfill sites were analysed and the microbial communities were compared during organic matter removal processes. The extracted DNA was amplified using FAM63F and HEX518R primers and T‐RFLP analysis was carried on with AluI digested terminal fragments. The bacterial populations of the wetland soil from Bury and Beccles landfill sites were absolutely dissimilar in the beginning of the treatment processes. But after four weeks of treatment the similarity was 45%. These community shifts can explain the effect of leachate on bacterial population. The T‐RFLP electropherograms indicated that the bacterial population of the bioreactor was very similar to the constructed wetland’s population in recent samples. The similarity within both sites might increase as the treatment process continues.     

Exploring the drivers of firm‐level innovation in the construction industry

A survey of 335 businesses in the Australian road industry has been carried out to ascertain those factors that make firms innovate. ‘Innovative’ is measured by adoption rates of advanced technologies and practices, and the range of innovation drivers reviewed encompasses business strategy and environment. The findings indicate that business strategies are more important than business conditions, and that the following three strategies are significant in differentiating between firms with high and low adoption rates: (1) hiring new graduates; (2) introducing new technologies; and (3) enhancing technical capabilities. The findings also highlight the importance of undertaking R&D and encouraging employee ideas for improvement. The public policy implications are that the quality of university graduates should be protected and advanced, as should technical skills within public sector client agencies.     

A case study on the soil–pile–structure interaction of a long span arched structure

Different concepts for modelling of soil-foundation in complete dynamic interaction analysis for a 110-m height 70-m span arched structure on 180 piles were investigated in this paper. The modelling approaches consisted of a sophisticated procedure to account for soil compliance and foundation flexibility by defining frequency-dependent springs and dashpots; namely, flexible-impedance base model. The results of this model were compared with those of the conventional modelling procedures; namely, fixed base model and flexible base model by defining frequency-independent springs. In the flexible-impedance base model, the substructure approach was employed through finite element modelling. To account for the kinematic interaction, the numerical model of the soil, foundation and piles were developed using a verified finite element model in ABAQUS. The free field time history and design spectrum were modified to obtain the foundation input motion. The impedance of pile groups with different length was obtained by the finite element model to assess the inertial interaction. The comparison of the results of the employed models showed that rocking and torsional responses were greatly affected by soil–structure interaction, indicating redistribution of seismic demands. It was also proven that the internal demands of the conventional model considering frequency-independent Winkler springs might be higher than those of the model including pile–soil–structure interaction effects.     

Just‐in‐time management in the ready mixed concrete industries of Chongqing,China and Singapore

Implementing just‐in‐time (JIT) management in the ready mixed concrete (RMC) industry seems viable. It has been observed previously by others that the current practices for managing the concrete supply chain upstream in terms of raw materials acquisition or prerequisite work on site were not geared toward JIT production. However, it is unclear if this observation is also relevant for the procurement of raw materials in the RMC industry in Chongqing (in China) and Singapore. Hence, the purpose of this study is to investigate the implementation status of JIT in the RMC industry in Chongqing and Singapore. The field study conducted found that all the RMC suppliers surveyed were using the demand pull system to manage RMC production and delivery to sites. However, the study also found that the raw materials could be purchased either using the JIT purchasing method or the traditional economic order quantity (EOQ) purchasing method. Further studies to investigate the conditions where a RMC supplier can adopt the JIT purchasing method to procure its raw materials are recommended.     

Response of reinforced concrete piles including soil–pile interaction effects

This paper discusses the importance of modeling soil–pile interaction in the response of reinforced concrete (RC) piles. A displacement-based, RC beam–column fiber model with distributed lateral deformable supports is presented first. The formulation is general and applies to both monotonic and cyclic loads. The proposed model is simple, computationally efficient and capable of representing the salient features of the soil–pile interaction, including dragging force and gap formation along the pile–soil interfaces as well as hysteretic responses of piles and surrounding soils. Two applications are presented to illustrate the model characteristics, to show the model capabilities, and to discuss the importance of modeling the pile–soil system. The first application deals with a single end-bearing pile embedded in a cohesionless soil. The proposed beam–column model is used to investigate the effects of different model parameters on the pile–soil response, including pile length, pile diameter, and pile and soil nonlinearities. The second application validates the accuracy of the proposed model with the experimental results of a cyclic test on a RC pile/shaft system where the influence of the pile–soil interaction is essential. Results from the correlation studies indicate that the proposed model can represent well both global and local responses of the pile–soil system. The effects of the interfacial characteristics between pile and soil on the system response are also studied.     

Persistence of pesticides in soil leachates: effect of pH ultra‐violet irradiation and temperature

The effects of pH, ultra‐violet irradiation and temperature on the persistence and breakdown of dieldrin, endosulphan, gamma‐HCH and pyrolan were studied in leachates from a loam soil. Except for dieldrin which remained exceptionally stable throughout the pH range, persistence of pesticides decreased progressively as pH increased. After exposure to ultra‐violet irradiation of 2537°A wavelength, dieldrin was appreciably broken down in activated charcoal. Pesticide losses from covered leachates incubated at different temperatures increased with increasing temperature.     

Colloid‐mediated transport of Pb through soil porous media

Intact soil column leaching experiments were used to assess the role of water dispersible soil colloids with diverse physicochemical and mineralogical composition in co‐transporting Pb in subsurface soil environments. There was essentially no elution of Pb (0 to < 1%) in 10mg/L control Pb solutions, suggesting a near complete attenuation by the soil column matrix. When the control Pb solutions were mixed with 300mg/L soil colloid suspensions, Pb transport increased by 10–3,000 times over that of control solutions. The presence of colloids increased the transport of both, the colloid bound and the soluble Pb fraction. Colloid‐induced transport was enhanced by increasing colloid surface charge, pH, organic carbon, and soil macroporosity and inhibited by increasing colloid size, Al, Fe, and quartz content. However, increased soil organic carbon content appeared to compensate for some of these limitations. Colloid binding and co‐transport appeared to be the dominant mechanism for increases in Pb transportability, but physical exclusion of soluble Pb species from matrix exchange sites blocked by colloids, competitive sorption, and organic complexation were also important. These findings suggest that the colloids play a dual role as Pb‐carriers and facilitators in the migration process and could have important ramifications on contaminant transport prediction and remediation applications.     

Soil–structure interaction effects on base-isolated buildings founded on soil stratum

The present study investigates the effects of soil–structure interaction (SSI) on the response of base-isolated multistory buildings founded on an elastic soil layer overlying rigid bedrock and subjected to a harmonic ground motion. Initially a four-degree-of-freedom system (4-DOF) is developed and the equations of motion are formulated in the frequency domain. Frequency independent expressions are used to determine the stiffness and damping coefficients for the rigid surface foundation on the soil-stratum underlined by bedrock at shallow depth. Assuming the foundation mass to be negligible, an equivalent two-degree-of-freedom (2-DOF) system is derived. The first mode of motion of the equivalent 2-DOF system appears to be sufficient to describe the response of the overall system for all ranges of stiffness and inertia properties of the structure and its isolation. An extensive parametric study demonstrates that SSI effects are significant, primarily for squat, light structures, founded on soil-stratum of low stiffness. The methodology could serve as a means to perform a preliminary seismic design of base-isolated building structures founded on homogenous soil-stratum over bedrock.     

n‐Alkane distributions in soil and water samples collected near Agbabu bitumen field of southwestern Nigeria

Soil and water samples from the vicinity of Agbabu bitumen field of Southwestern Nigeria were analysed by GC‐FID for n‐alkanes, in order to characterize their distributions and to gather information on the degree of contamination by bitumen exploration and processing and other biogenic contributions. Total concentrations of n‐alkanes in water and soil samples analysed ranged from 61.5 to 472.7 µg L^?1 and 422.8 to 2289.4 ng g^?1 dw, respectively. On the basis of the total n‐alkane concentrations, carbon preference index (CPI) values and the odd‐even carbon predominance, it is suggested that both natural (e.g. aquatic input) and anthropogenic (e.g. bitumen and synthetics) sources contribute to the n‐alkanes load in soil and water samples of the area studied.     

Effects of ferric iron on the anaerobic treatment and microbial biodiversity in a coupled microbial electrolysis cell (MEC) – Anaerobic reactor

Adding Fe(III) into a MEC – anaerobic reactor enhanced the degradation of organic matters. To clarify the respective effects of combining Fe(III) dosage and a MEC and Fe(III) dosage only on strengthening anaerobic digestion, three anaerobic reactors were operated in parallel: a MEC – anaerobic reactor with dosing Fe(OH)₃ (R1), an anaerobic reactor with dosing Fe(OH)₃ (R2) and a common anaerobic reactor (R3). With increasing influent COD from 1500 to 4000 mg/L, the COD removal in R1 was maintained at 88.3% under a voltage of 0.8 V, which was higher than that in reactor R2 and R3. When the power was cut off, the COD removal in R1 decreased by 5.9%. The addition of Fe(OH)₃ enhanced both anaerobic digestion and anodic oxidation, resulting in the effective mineralization of volatile fatty acids (VFAs). The reduced Fe(II) combined with electric field resulted more extracellular polymeric substances (EPS) production. Quantitative real – time PCR showed a higher abundance of bacteria in the anodic biofilm and R1. Pyrosequencing and denaturing gradient gel electrophoresis (DGGE) analysis revealed that the dominant bacteria and archaea communities were richer and more abundant in the anode biofilm and R1.     

On the frictional property of lubricants and its impact on jacking force and soil–pipe interaction of pipe-jacking

Lubricants are frequently applied in pipe-jacking, especially under difficult geological conditions or in cases of a longer alignment. The main purpose of lubricant application is to reduce the friction between pipe and soil. However, it is very difficult to quantitatively determine the real contact conditions between the two. New technology for soil–pipe interaction measurement is still scarce and requires further development. Only indirect methods are available for practical measurement of soil–pipe interaction, and engineering judgment is required for the application of those measurements. In this study, a simple test method was applied to obtain the frictional properties of the most popular lubricants in the Taiwan area. Those frictional properties were used for jacking force estimation and numerical analysis of soil–pipe interaction for linear and curved pipe-jacking. The analyses of jacking force show that reduction in jacking force is closely related to reduction in friction coefficients, and the effect of lubrication is slightly more significant in the case of curved alignment than the case of linear alignment. In addition, a study of a 400-m linear pipe-jacking case in the Taichung Science Park shows overestimation of the jacking force by an empirical formula. It reveals the reduction in pipe-soil contact area induced by over-cutting is significant for pipe-jacking in gravel formations.     

Effects of soil–pile interaction on the response of bridge pier to barge collision using energy distribution method

Abstract

In this paper, the effects of soil–structure interaction (SSI) on the response of a girder bridge pier is evaluated by assessing the energy distributions in the barge–pier collision system. The finite-element models of two example piers of St. George Island Causeway Bridge, which have different structural and geometrical characteristics, are developed in LS-DYNA software to simulate the barge–pier collision scenarios. By comparing the energy distribution results among the barge and pier components, it is obtained that barge bow component has greater value of the internal energy contribution than pier components in the barge collision with more stiff pier. While, in the barge collision with more flexible pier, the pier components including the pier structure, piles and SSI have more internal energy contributions than the barge component. In addition, From the comparison of energy absorbed by the pier structure between the cases with and without SSI, it is found that the effect of the substructure and its relevant SSI on the response of the more flexible pier affected by the produced large deformations and relative displacements of the pier substructure, is more than that of stiff pier which displaces with semi-rigid and global deflections.