Falling rock hazard index: a case study from the Marun Dam and power plant, south-western Iran

Rock fall phenomena are a major hazard during construction in mountainous regions. At the Marun Dam site, rock falls occur almost every day on the downstream side. The left flank power plant and access roadways as well as the right flank roadways are susceptible to rock falls from the 100?m high cliffs with slopes of 70??0°. The cause is a combination of the orientation of the bedding planes and joint sets and the active tectonic setting of the area. The paper reports the use of RocFall and Dips software to simulate the conditions in order to define the potential risk of rock falls at the Marun Dam site, which could affect workers as well as structures. In the light of the Falling Rock Hazard Index obtained, preventative and remedial measures are suggested.     

Modelling of cold-formed steel sandwich purlin-sheeting systems to estimate the rotational restraint

Sandwich panels are attached to cold-formed steel purlins in roofs of industrial buildings to provide insulation. As the strength of the attached purlins is considerably increased due to the lateral and rotational restraints provided by the sandwich panels, estimating these restraints is important in the design of purlins. The rotational restraint is generally determined by experiments, as no design rules exist for sandwich purlin-sheeting systems. In this paper, a non-linear finite element model is presented to estimate the rotational restraint provided by the sandwich panels to the attached purlin. The model is validated with experimental tests and is in good agreement. In order to develop a design method for estimating the rotational restraint in sandwich purlin-sheeting systems, the model could be useful for parametric studies to investigate the influencing factors.     

Influence of chitosan characteristics on the coagulation and the flocculation of bentonite suspensions

Ten chitosan preparations with different molecular weights (MW) and degrees of deacetylation (DD) were tested for coagulation of 5 g L(-1) bentonite suspensions at pH 5 and 7 in demineralized water (DW) and in tap water (TW). Coagulation was better in TW than in DW for every condition and lower doses of chitosan were required at pH 5 than at pH 7. More than 95% of residual turbidity (after sedimentation in the absence of chitosan) was removed using less than 0.10 mg L(-1) chitosan in either TW or DW at pH 5 or in TW at pH 7. Higher doses were required for removal of turbidity in DW at pH 7, but in all cases the effective concentrations of chitosan were much lower than required for complete neutralization of the negative charge on the bentonite particles. Removal of turbidity was best for the higher MW chitosans in either the B series (89.5% DD) or the C series (95% DD) of chitosans. Overall, the results were consistent with destabilization of bentonite by the combined mechanisms of electrostatic patch and bridging. The improved performance of chitosan in TW could have been due to improved attachment to bentonite due to the presence of sulfate and other counter-ions in TW.     

On coupling 1D non-isothermal heat and mass transfer in porous materials with a multizone building energy simulation model

Hygroscopic materials available in the interior of buildings such as wood, gypsum, paper etc, are able to absorb moisture if the relative humidity of the room increases and release it again if the relative humidity decreases. This moisture buffering phenomenon is often accounted for in a simplified way in Building Energy Simulation programs (BES) e.g. TRNSYS, which limits their applicability. Nevertheless several building applications require an accurate prediction of the indoor relative humidity already from the design stage.     

Trace organic solutes in closed-loop forward osmosis applications: Influence of membrane fouling and modeling of solute build-up

In this study, trace organics transport in closed-loop forward osmosis (FO) systems was assessed. The FO systems considered, consisted of an FO unit and a nanofiltration (NF) or reverse osmosis (RO) unit, with the draw solution circulating between both units. The rejection of trace organics by FO, NF and RO was tested. It was found that the rejection rates of FO were generally comparable with NF and lower than RO rejection rates. To assess the influence of fouling in FO on trace organics rejection, FO membranes were fouled with sodium alginate, bovine serum albumin or by biofilm growth, after which trace organics rejection was tested. A negative influence of fouling on FO rejection was found which was limited in most cases, while it was significant for some compounds such as paracetamol and naproxen, indicating specific compound-foulant interactions. The transport mechanism of trace organics in FO was tested, in order to differentiate between diffusive and convective transport. The concentration of trace organics in the final product water and the build-up of trace organics in the draw solution were modeled assuming the draw solution was reconcentrated by NF/RO and taking into account different transport mechanisms for the FO membrane and different rejection rates by NF/RO. Modeling results showed that if the FO rejection rate is lower than the RO rejection rate (as is the case for most compounds tested), the added value of the FO-RO cycle compared to RO only at steady-state was small for diffusively and negative for convectively transported trace organics. Modeling also showed that trace organics accumulate in the draw solution.     

Differential uptake of U,Mo and Cu,by roots,stalks and seeds of oats grown on uranium‐rich soils

The uptake of U, Mo and Cu by oats grown in high uranium containing soils was investigated. Roots of the plant were found to constitute an effective barrier to U uptake, while that of Mo was pH dependent. Cu concentrations in the plant were independent of those of the other two metals.     

Second interlude: on the house from all sorts of angles

The planning and design of environments for healthcare is complex and at times contradictory. Research and critical discourse have been fragmented and have not provided the degree of support required by the architectural profession. This dilemma is compounded by the enormous capital investment countries around the globe expend annually to promote the health status of their citizens. To help rectify this situation, landmark international developments in the relationship between architecture and health are outlined within a dualistic conceptual framework that is part historical and part futurist. Prognostications for the year 2050 are offered on issues concerning the rise of alternative care settings to the traditional acute care hospital. This portion of the discussion examines the rising importance of home- and community-based care, the functions of nature as a therapeutic modality, patient empowerment, the critical need for socially equitable and sustainable environments for healthcare, and the need for new paradigms in the planning and design of therapeutically supportive care and treatment settings. Two developments in particular, functional deconstruction and residentialism, are described in some detail as is the critical role of interdisciplinary approaches in meeting the global research and practice challenges which lie ahead in this century.     

Epilogue: on meaning and experience (or images versus practices)

The essay presents an alternative idea of what Islamic architecture could be from what is termed as a ‘value-centred’ approach. To date, the theory of Islamic architecture has been mainly derived either from a formalistic analysis of historically selected buildings from the past, or from the works of Sufism which claim to be the form generator of the Islamic spirit. There are also the works of regionalist architects that maintain the idea of Islamic architecture as being a product of cultural and environmental as well as geographical forces. The essay instead presents the argument that since modernist architecture was the product of a value-centred discourse ranging across political, religious and environmental issues, then Islamic architecture could also be derived from an examination of the values inherent in the hadith or traditions of the Prophet Muhammad. The body of hadiths contains many accounts of the Prophet's values concerning life practices of which some can be used in order to derive a framework of architectural design. With this framework, a re-evaluation of past historical works can be carried out and new building designs can be made from the interpretation of hadiths within the context of the cultural, geographical, economic and political settings of each project.     

Brominated flame retardants in Belgian home-produced eggs: levels and contamination sources

The extent and the sources of contamination with brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD), in home-produced eggs from free-foraging chicken of Belgian private owners were investigated. Various factors, such as seasonal variability, exposure of chickens through diet (kitchen waste) and soil, and elimination of BFRs through eggs and faeces were assessed. PBDEs were more important than HBCD in terms of concentrations and detection frequency. Concentrations of PBDEs and HBCD in Belgian home-produced eggs were relatively low and comparable with reported levels from other European countries and the US. The concentrations of PBDEs (sum of 13 congeners, including BDE 209) ranged between not detected and 32 ng/g lipid weight (lw), with medians of 3.0 and < 2.0 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively. When present, BDE 209 was the major PBDE congener (45% of sum PBDEs). When BDE 209 was not detected, the PBDE profile was composed of PentaBDE (BDE 99 and BDE 47), with, in some cases, higher contribution of OctaBDE (BDE 183 and BDE 153). HBCD was also detected (< 0.4 and 2.9 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively), but at lower detection frequency. The highest HBCD value was 62 ng/g lw. The similarity between profiles and seasonal variations in the concentrations of BFRs in soil and eggs indicate that soil is an important source, but not the sole source, for eggs laid by free-foraging chicken. The contamination of eggs with PBDEs and HBCD appears to be of low concern for public health and the contribution of eggs to the total daily intake of PBDEs appears to be limited (10% for chicken owners and 5% for the average Belgian consumer).