BP Network Based Mix Proportion Design of Self-Compacting Concrete
It was known that many parameters of raw materials, such as, strength of cement, mud content and modulus of fineness of river sand, maximum size of aggregate, content of' needle-like/sheet-like crushed stone, loss of ignition and fineness of fly ash, may exert significant influence on the theology and mechanical properties of self compacting concrete(SCC). It is a dream of researchers to identify the influencing degree of various factors on performance of SCC so as to obtain optimal properties. By virtue of BP neural network approach, this paper employed strength of cement, mud content and fineness modulus of fineness of river sand, maximum size of aggregate, content of needle-like/sheet-like crushed stone, loss of ignition and fineness of fly ash as the input parameters, and the corresponding optimized mix proportion as the output to describe the nonlinear relationship between them. And the orthogonal experiment was designed for the purpose of training and verification of network. The results demonstrated that the pre-trained BP neural network trained by orthogonal test data may employ to predict the optimal concrete mix proportion. This approach may replace some waste-time and heavy laboratory tests. In addition, such method may real-time optimize mixture proportion. of self-compacting concrete, which has great effect on the quality control of manufacturing self-compacting concrete.
Experimental and numerical studies in self-compacting concrete
This thesis describes the steps taken to develop normal strength (30-80 MPa) selfcompacting 
concrete mixes with 20mm maximum size aggregate. For the selfcompacting 
concrete mixes with 20mm maximum size of aggregate fulfilment of the 
flow and cohesiveness criteria are found insufficient for the mix design. It is found that 
they must additionally meet the passing ability criterion. 
A Lagrangian particle based method, the smooth particle hydrodynamics (SPH), is used 
to simulate the flow of SCC mixes. An incompressible SPH method is employed to 
simulate the flow of such non-Newtonian fluids whose behaviour is described by a 
Bingham-type model, in which the kink in the shear stress versus shear strain rate 
diagram is first appropriately smoothed out. The basic equations solved in the SPH are 
the incompressible mass conservation and Navier-Stokes equations. 
The yield stress of SCC mixes is predicted in an inverse manner using the SPH 
simulation methodology and matching the measured and simulated t500, tstop and the 
final spread of the cone flow test. It is found that the yield stress of SCC mixes varies 
only slightly with an increase in the characteristic compressive strength of the mix. The 
plastic viscosity on the other hand shows a marked increase. The latter was estimated by 
a micromechanical procedure proposed by Ghanbari & Karihaloo (2009) based on the 
measured viscosity of the cement paste alone and on the volume fractions of the mix 
constituents. 
The SPH simulation methodology was also used for predicting the distribution of large 
coarse aggregates in the cone spread. This distribution was found to be indeed very 
similar to that revealed in the cut sections of the hardened test cone spread. These large 
coarse aggregates had been painted with non-toxic non-water soluble paints prior to 
being used in the test mix. 
The simulation of SCC mixes revealed that the cone lift rate in the slump flow test has a 
significant effect on the flow pattern and the measured t500. The latter decreases as the 
cone lift rate increases from 0.1 to 1 m/s. The effect on the spread (i.e. tstop) is, however, 
insignificant.
Inequality trends in health and future health risk among English children and young people, 1999–2009
Objective To investigate trends in health inequality among children and young people between 1999 and 2009, using outcomes consistent with the current NHS reforms. Design/data Secondary analysis of participants aged 0–24 in the Health Surveys for England (HSE) undertaken in 1999, 2004, 2006 and 2009. Main outcome measures Changes in the absolute and relative risks of four health outcomes by deprivation tertiles, based on occupation of the head of household ▸ self/parent-reported general health, ▸ presence of a long-standing illness (LSI), ▸ obesity ▸ smoking. Results No indicator showed a reduction in relative or absolute inequality between 1999 and 2009. For children (0–12 years), the relative risk comparing the most and least deprived tertiles increased significantly for poor general health (1999:1.6 (95% CI 1.2 to 2.2); 2009:3.9 (2.4 to 6.2), while the absolute difference in LSI prevalence(%) increased from 1.3 (−2.9 to 5.5) to 7.4 (3.6 to 11.4). Among young people (13–24 years), the absolute difference in LSI prevalence increased from −5.9 (−10.9 to −1.1) to 3.1 (−4.1 to 10.7). Absolute inequality in having tried smoking among children aged 8–15(%) increased significantly in the first half of the decade before decreasing in the second half (1999:3.3 (−1.1 to 7.7); 2004:14.1 (9.6 to 18.8); 2009:4.1 (0.1 to 8.8)). However, the increase in absolute inequality for smoking prevalence among young adults (16–24 years) was maintained throughout the decade (1999:−7.0 (−15.6 to 1.3); 2004:11.6 (3.7 to 20.0); 2009:8.2 (−0.3 to 16.9)). Conclusions The national programme between 1999 and 2009 was not successful in reducing inequality in four key indicators of health status and future health risk among children and young people. Some inequality measures for general health, LSI prevalence and smoking increased over this time.