In this paper, the recently introduced series active variable geometry suspension (SAVGS) for road vehicles is experimentally studied. A realistic quarter-car test rig equipped with double-wishbone suspension is designed and built to mimic an actual grand tourer real axle, with a single-link variant of the SAVGS and a road excitation mechanism implemented. A linear equivalent modeling method is adopted to synthesize an H-infinity control scheme for the SAVGS, with the geometric nonlinearity compensated. Simulations with a theoretical nonlinear quarter-car indicate the SAVGS potential to enhance suspension performance, in terms of ride comfort and road holding. Practical features in the test rig are further considered and included in the nonlinear model to compensate the difference between the theoretical and testing behaviors. Experiments with a sinusoidal road, a smoothed bump and hole, and a random road are performed to evaluate the SAVGS practical feasibility and performance improvement, the accuracy of the model, and the robustness of the control schemes. Compared with the conventional passive suspension, ride comfort improvements of up to 41% without any deterioration of the suspension deflection are demonstrated, while the SAVGS actuator power is kept very low, at levels below 500 W

In order to examine perinatal mortality and prevalence of major congenital malformations in twins, deliveries in four teaching hospitals in Taipei City were studied. Among a total of 73,264 deliveries from October 1985 to June 1989, there were 844 pairs of twins. The zygosity of the twin pairs was determined by sex, placentation and 12 red blood cell antigens. There were 482 MZ and 252 DZ twin pairs identified, but the zygosity of a further 110 twin pairs was indeterminable due to lack of information on plancentation and/or blood types. A total of 4,573 singletons delivered in one study hospital from July 1986 to June 1987 were also studied as controls. The perinatal mortality rate was 7.5% for MZ twins, 1.4% for DZ twins, and 0.7% for singletons. The concordance rate of perinatal death was significantly higher in MZ (60%) than in DZ (0%) twins. The prevalence of major congenital malformations was 2.7% for MZ twins, 1.0% for DZ twins, and 0.6% for singletons. The concordance rate of major congenital malformations was 18% for MZ twins, but no DZ pair was concordant in any major congenital malformation. The concordance rate of facial clefts was 29% for MZ twins. There were 2 sets of conjoined twins giving a prevalence rate of 2.7 per 100,000 deliveries. These findings showing the prevalence of perinatal mortality and major congenital malformation to be highest in MZ twins, intermediate in DZ twins and lowest in singletons, suggest the importance of intrauterine environments in the determination of perinatal mortality and congenital malformations.

In this paper, a novel electromechanical active suspension for cars, the parallel active link suspension (PALS) is proposed and then experimentally studied. PALS involves the introduction of a rotary-actuator-driven rockerpushrod mechanism in parallel with the conventional passive suspension assembly, to exert an additional controlled force between the chassis and the wheel. The PALS geometric arrangement is designed and optimized to maximize the rocker torque propagation onto the tire load increment. A quarter-car test rig with double wishbone suspension is utilized for the PALS physical implementation. Based on a linear equivalent model of the PALS quarter car, a conservative and an aggressive robust H ∞ control schemes are synthesized separately to improve the ride comfort and the road holding, with different levels of control effort allowed in each of the control schemes. Simulations with a theoretical nonlinear model of the PALS quarter car are performed to evaluate the potential in suspension performance enhancement and power demand in the rocker actuator. Experiments with a harmonic road, a smoothed bump and hole, and swept frequency are conducted with the quarter-car test rig to validate the practical feasibility of the novel PALS, the ride comfort enhancement, and the accuracy of the theoretical model and of a further nonlinear model in which practical features existing in the test rig are identified and included.

Polyamide‐11 (PA11)/clay nanocomposites were prepared by in situ intercalative polymerization. The crystal morphology and crystallization kinetics of these nanocomposites were investigated via polarized light microscopy (PLM), small‐angle laser scattering (SALS) and differential scanning calorimetry (DSC). PA‐11 can crystallize into well‐formed spherulites, while only very tiny crystallites were observed by PLM and SALS for the nanocomposites. Both isothermal and non‐isothermal crystallization methods were employed to investigate the crystallization kinetics by DSC. Both techniques showed an increased crystallization rate with the addition of clay. However, the Avrami exponent decreased with the addition of clay in isothermal crystallization but showed a wide range of values depending on the cooling rate in the non‐isothermal crystallization. The changes in crystal morphology and crystallization kinetics can be understood as being due to the ‘supernucleating’ effect of the nanodispersed clay layers. Copyright © 2004 Society of Chemical Industry

Background:To investigate the surveillance trend of birth defects, incidence, distribution, occurrence regularity, and their relevant factors in Xi’an City in the last 10 years for proposing control measures.Methods:The birth defects monitoring data of infants during perinatal period (28 weeks of gestation to 7 days after birth) were collected from obstetrics departments of all hospitals during 2003–2012. Microsoft Excel 2003 was used for data input, and Statistical Package for the Social Sciences version 16.0 (International Business Machines Corporation, New York, NY, USA) was used for descriptive analysis. χ2 test, Spearman correlation and linear-by-linear association trend test were used for statistical analyses.Results:The birth defect rate declined from 9.18% in 2003 to 7.00% in 2012 (χ2 = 45.001, P < 0.01) with a mean value of 7.85%, which is below the Chinese national average level (χ2 = 20.451, P < 0.01). The order of five most common birth defects has changed. The incidence of congenital heart disease (CHD) increased with time, particularly after 2012, it became the most frequent type (rs = 0.808, P < 0.001). Till then, the number of neural tube defects (NTDs) declined significantly (χ2 = 76.254, P < 0.01). The average birth defects rate of 8.11% in rural areas was higher than that in urban areas (7.56%, χ2 = 7.919, P < 0.01) and much higher in males (8.28%) than that in females (7.18%, χ2 = 32.397, P < 0.01). Maternal age older than 35 years (χ2 = 35.298, P < 0.01) is the most dangerous age bracket of birth defects than maternal age younger than 20 years (χ2 = 7.128, P < 0.01).Conclusions:A downward trend of birth defects was observed in Xi’an City from 2003 to 2012. NTDs significantly decreased after large-scale supplemental folic acid intervention, while the incidence rate of CHD significantly increased.