A systems view of temporary housing projects in post‐disaster reconstruction

Natural cataclysms (earthquakes, hurricanes and so forth) become natural disasters when they coincide with vulnerabilities; unfortunately, informal settlements in developing countries are only too often highly vulnerable – a reality amply and unhappily confirmed by available statistics. In this context, reconstruction projects are sandwiched between the short‐term necessity to act promptly and the long‐term requirements of sustainable community development – a situation that is currently reflected in alternative and conflicting paradigms at the policy level.

Adopting a case‐study approach, we explore the use of temporary housing within two post‐disaster environments, where the impact of different organizational designs leads to fundamentally different solutions to the short‐term housing problem.

Our research adopts a dynamic systems approach, associating strategic organizational team design with the development of tactical technical proposals. Two case studies from Turkey and Colombia show that a coherent approach to the sequential stages of providing immediate shelter, temporary housing and permanent reconstruction is not always obtained. The research results emphasize that the performance of reconstruction projects is directly linked to the design and management of the project team.     

Are cats and dogs the major source of endotoxin in homes?

Previous studies have suggested that exposure to cats and dogs during early childhood reduces the risk of allergic disease, possibly by increasing home endotoxin exposure. This study asked the question of whether cats and dogs are the dominant influence on dust endotoxin concentrations in homes after considering other variables reportedly associated with endotoxin. The presence of cats or dogs in homes, household and home characteristics, and dust endotoxin concentrations from 5 locations were assessed in 966 urban and suburban homes. Whether considered together as pets or as cats and dogs separately, the presence of cats and dogs significantly contributed to living room and bedroom floor endotoxin concentrations, but not to bed endotoxin concentrations. However, the two variables consistently related to endotoxin in all home sites were the home occupant density (occupants/room) and cleanliness of the home. Our data suggest that reducing occupant density and improving home cleanliness would reduce home endotoxin concentrations more than removing pet cats or dogs from the home.     

Velocity-Dependent Adhesion with Lubricants on Thin-Film Disks

The well-known problem of stiction in a magnetic disk drive largely depends on the forces induced by the presence of a thin liquid film. It is commonly recognized that both adhesive and viscous effects contribute to the magnitude of the stiction force, but is is not known what relative roles the two effects have in a lubricated contact. In the present work, the nature of adhesive and viscous effects is investigated for the slider/disk interface under conditions of constant-speed sliding.

Friction measurements are conducted over a range of sliding speeds, 0.25-250 mm/s, with eight perfluoropolyether (PFPE) lubricants applied in various thicknesses, 0-6.6 nm, to carbon-coated magnetic thin-film disks. The lubricants were selected to cover a broad range of viscosities. For several sliding speeds and lubricant film thicknesses, the friction force is found to decrease significantly with increasing sliding speed for all lubricants. In several instances, large friction forces are observed at the lowest sliding speeds, indicating stiction-like behavior, whereas, at higher speeds, the friction is reduced to even below unlubricated friction levels. At the highest film thickness and sliding speed, the friction was found to increase with speed for some lubricants. The implications of these results on current models of lubricant-mediated adhesion are discussed.     

Reverse anatomy shoulder replacement: comparison of two designs

The aim of this study was to use a biomechanical model of the shoulder to examine the characteristics of two concepts of reverse anatomy implant; those that preserve the natural glenohumeral centre such as the Bayley-Walker (B-W) replacement and those medializing it such as Delta. A biomechanical model of the shoulder was used to evaluate the biomechanical characteristics of these prostheses. The moment arms of the shoulder muscles were predicted for the implanted models over a wide workspace and were compared to those of natural anatomy. The deltoid muscle moment arms through almost all of the range of motion in the Delta model were greatest. As a result the shoulder joint contact force was decreased for this implant. Furthermore, although the B-W model predicted similar moment arms to natural anatomy, the contact force decreased owing to change in the joint constraints. Finally, it was concluded that the reverse anatomy can compensate for loss of rotator cuff muscles in terms of joint stability, yet the shoulder function depends on the individual's musculature.     

Wear of Carbon-type Seal Materials with Varied Graphite Content

Most carbon-type seal materials contain graphitic carbon as the minor constituent. Materials having graphite carbon as the major constituent were studied as possible seal materials at 10,000 feet per minute sliding velocities, in most experiments the temperature of the mating surfaces was 500°F. Carbon materials made graphitic by electro-graphitization were too soft; they gave high wear and high friction. Bodies molded with high-graphite-content materials and made hard by improved molding methods and impregnation gave acceptable friction and wear properties.

When a hardenable stainless steel was used, the effect of varied hardness of mating surface on wear of typical carbon was slight. Within a limited range, roughness of mating surface is not important to wear of carbons.     

Wear and Friction of Filled Polytetrafluoroethylene Compositions in Liquid Nitrogen

Wear and friction behavior of slider materials at cryogenic temperature is important to the development of seals and bearings for missile powerplants. Data were obtained in liquid nitrogen (?320°F) with a series of molded and extruded polytetrafluoroethylene (PTFE) compositions containing various filler materials. A 3/16-in. radius rider specimen (PTFE materials) was caused to slide in a circumferential path on the flat surface of a rotating 2½-in. diameter disk specimen (usually type 304 stainless steel). The sliding velocity was usually 2300 ft per min and the load was 1000 grams.

As compared with reference steels and carbons used in conventional seals and bearings, the filled PTFE compositions gave low wear and friction (friction coefficients from 0.06 to 0.13) in liquid nitrogen. Several extruded compositions have particular promise for seal and bearing materials. An extruded glass-filled material gave wear and friction that was essentially unaffected by sliding velocities to 6000 ft per min.     

Pressure-Viscosity Measurements for Several Lubricants to 5.5 × 108 Newtons Per Square Meter (8 × 104 PSI) and 149 C (300 F)

A capillary viscometer was used to measure viscosity as a function of pressure, temperature, and shear stress for a number of lubricants. Measurements were made at 38 C, 99 C, and 149 C (100 F, 210 F, and 300 F), gauge pressure to 5.5 × 10⁸ N/m² (8 × 10⁴ psi), and shear stresses to 10⁶ N/m² (14.5 psi). At 38 C (100 F), the order of the pressure-viscosity coefficients for the unformulated fluids was: fluorinated polyether > synthetic hydrocarbon > naphthenic mineral oil > synthetic paraffinic oil (lot 4) > C-ether ? synthetic paraffinic oil (lot 3) > polyalkyl aromatic > advanced ester. All pressure viscosity coefficients decreased with increasing temperature. Fair agreement was obtained when pressure-viscosity coefficients at 38 C (100 F) and 6.9 × 10⁷ N/m² (10⁴ psi) were compared to data from other investigators using different techniques (optical elastohydrodynamics, oscillating crystal, and low shear capillary viscometry).     

Temporary and Permanent Viscosity Loss Correlated to Hydraulic System Performance

ABSTRACT

Straight- and multigrade fluids were evaluated in a hydraulic dynamometer that incorporated a pressure-compensated axial piston pump and a fixed displacement axial piston motor. Pump, motor, pressure compensator, and directional control valve internal flow losses were determined under various conditions of pressure, speed, and temperature. Fluid samples were collected before and at various times during the dynamometer experiments, and viscosity measurements were performed to probe for correlations between viscosity, operating time, and system leakage flow losses. The low shear rate viscosities of the multigrade fluids decreased linearly throughout the duration of testing due to polymer degradation. However, system flow losses did not exhibit a statistically significant increase as the multigrade fluids sheared down. The fluids were also characterized by their permanent viscosity loss produced in sonic shear and tapered bearing tests and by their temporary shear thinning measured in an ultra-high-shear viscometer at several temperatures. The effects of these viscous properties were analyzed using an empirical model to identify which measures of viscosity were most correlated with flow loss. The results suggested that the relative contributions of temporary and permanent viscosity loss change as the fluid is used. Further, analysis of torque loss and input power revealed that input power and losses are more useful indicators of the effect of fluids on hydraulic system performance than pump efficiency.     

Characterization of Fractionated Soy Proteins Produced by a New Simplified Procedure

It was possible to fractionate soy protein into two soy protein isolate fractions (>90% protein) enriched in either glycinin or β-conglycinin by using a new simplified procedure (referred to as the Deak procedure) employing CaCl₂ and NaHSO₃. The Deak procedure produced fractions with higher yields of solids, protein, and isoflavones, and similar protein purities as well as improved functional properties compared to fractions recovered by established, more complex soy protein fractionation procedures. The Deak glycinin-rich fraction comprised 15.5% of the solids, 24.4% of the protein, and 20.5% of the isoflavones in the starting soy flour, whereas the glycinin-rich fraction of the established procedure (Wu procedure) comprised only 11.6% of the solids, 22.3% of the protein, and 9.6% of the isoflavones. The Deak β-conglycinin-rich fraction comprised 23.1% of the solids, 37.1% of the protein, and 37.5% of the isoflavones in the starting soy flour, whereas the Wu β-conglycinin-rich fraction comprised only 11.5% of the solids, 18.5% of the protein, and 3.3% of the isoflavones. Protein purities were >80% for both fractions when using both procedures. The Wu procedure produced protein fractions with slightly higher solubilities and similar surface hydrophobicities; whereas, the fractions produced by the Deak procedure had superior emulsification and foaming properties and similar dynamic viscosity behaviors.     

Separating Oil from Aqueous Extraction Fractions of Soybean

Previous research has shown that enzyme-assisted aqueous extraction processing (EAEP) extracts 88–90% of the total soybean oil from extruded full-fat soy flakes into the aqueous media, which is distributed as cream (oil-in-water emulsion), skim, and free oil. In the present work, a simple separatory funnel procedure was effective in separating aqueous skim, cream and free oil fractions allowing mass balances and extraction and recovery efficiencies to be determined. The procedure was used to separate and compare liquid fractions extracted from full-fat soy flour and extruded full-fat soy flakes. EAEP extracted more oil from the extruded full-fat soy flakes, and yielded more free oil from the resulting cream compared to unextruded full-fat soy flour. Dry matter partitioning between fractions was similar for the two procedures. Mean oil droplet sizes in the cream and skim fractions were larger for EAEP of extruded flakes compared to non-enzymatic AEP of unextruded flour (45 vs. 20 μm for cream; 13 vs. 5 μm for skim) making the emulsions from EAEP of extruded flakes less stable. All major soy protein subunits were present in the cream fractions, as well as other fractions, from both processes. The cream could be broken using phospholipase treatments and 70–80% of total oil in the extruded full-fat flakes was recovered using EAEP and a phospholipase de-emulsification procedure.