Resistance Factor of Caisson-Tip with Internal Fillet for Suction Caissons Penetrating into Clay

This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson-tip are obtained in terms of the caisson-tip geometry ratio of the flat section of the caisson-tip to the caisson wall thickness m/t and adhesion factorsα_i along inside of caisson wall andα_b at the base of the caisson-tip.It is indicated that the factor N_c increases with the increase of m/t,α_i and a_b.The resistance factors N_c for the rough base(α_b=1)are larger by 0.57than that for the smooth base(α_b=0).Besides,the factors N_c of caisson-tip with flat base(m=t)are larger by 1.14 than that with full internal fillet(m=0).The required suction to penetrate suction caissons with various fillets is obtained in terms of the force equilibrium in vertical direction.The finite element limit analysis and centrifuge model test results are used to verify the rationality of the presented failure mechanisms and theoretical predictions.

Necessity and feasibility of improving the residual resistance factor of polymer flooding in heavy oil reservoirs

The efficiency of water flooding in heavy oil reservoirs would be improved by increasing the viscosity of the displacing phase, but the sweep efficiency is not of significance due to the low mobility of the vicious oil. On the basis of mobility control theory, increasing the residual resistance factor not only reduces the water-oil mobility ratio but also decreases the requirement for viscosity enhancement of the polymer solution. The residual resistance factor caused by hydrophobic associating polymer solution is higher than that caused by polyacrylamide solution in brine containing high concentrations of calcium and magnesium ions. The results of numerical simulations show that the polymer flooding efficiency improved by increasing the residual resistance factor is far better than that by only increasing solution viscosity. The recovery factor of heavy oil reservoirs （70 mPa·s） can be enhanced by hydrophobic associating polymer solution of high residual resistance factor （more than 3） and high effective viscosity （24 mPa·s）. Therefore, increasing the residual resistance factor of the polymer solution not only decreases the requirement for the viscosity of polymer solution injected into heavy oil reservoirs but also is favorable to enhanced oil recovery during polymer flooding.

Reliability-Based Load and Resistance Factors Design for Offshore Jacket Platforms in the Bohai Bay:Calibration on Design Factors

For the fulfillment of the probability-based structural design for the offshore jacket platforms in the Bohai Bay, the design factors of loads, resistance and load combinations are much necessary to be calibrated according to the proposed target reliability index. Firstly, the limit states function for the offshore jacket platforms is introduced. Then, four approaches to calibrate the factors of load and resistance are presented and compared. Afterwards, the methods to calibrate the load combination factors are developed. Finally, the factors of load, resistance and load combination for the offshore jacket platforms in the Bohai Bay are calibrated and the corresponding design formulae are recommended. The results are proved to be rational in practice, and also illustrate that the proposed target reliability index for offshore jacket platforms in the Bohai Bay is also appropriate.

Resistance factors for design of slopes in a homogenous soil layer

Traditionally,the factor of safety(FOS)is widely used to account for uncertainties in the design of slopes within the framework of working stress design.As the uncertainties involved in the design of slopes vary,the same FOS may correspond to the different levels of reliability.In this study,the advanced first order reliability method is used to determine the resistance factors for design of slopes in a homogenous soil layer.It is found that the resistance factors depend on the target reliability index,the height of the slope,and the variability of the soil strength parameters.It is difficult to suggest a unique set of resistance factors for design of slopes.Analytic solutions are developed to determine the resistance factors for design of slopes assuming the random variables are normally distributed.An approximate method based on the concept of equivalent target reliability index is also suggested to determine the resistance factors for design of the slope when the soil strength parameters are lognormally distributed.The method suggested in this paper provides a practical way to perform load and resistance factors design of slopes.

Calibration of LRFD Format for Steel Jacket OffshorePlatform in China Offshore Area(2): Load, Resistance and Load Combination Factors

Adopting the load and resistance factor design format, the design method for steel jaeket platform structures is developed. Firstly, the limit state equations and design format for steel jacket platform structures are introduced. Then, the ratio of live load effect to dead load effect is estimated. The target reliabilities for design of offshore structures in China offshore area are calibrated by past practice in API RP2A-WSD code. The load and resistance factors are optimized by minimizing the difference within the target reliability and the resulting reliability over the range of load effect ratios. Considering the concurrence of different loads, load combination factors are obtained through an optimization process, and the relation between the load combination factor and load correlation coefficient is established. Finally, the design formulae for steel jacket structures in China offshore area are recommended.

Estimation of load and resistance factors using the thirdmoment method based on the 3P-Iognormal distribution

Load and resistance factors are generally obtained using the first order reliability method(FORM)in which the design point should be determined and derivative-based iterations used.In this article,the thirdmoment reliability index,based on the three-parameter lognormal(3P-lognormal)distribution,is investigated.A simple method based on the third-moment method for estimating load and resistance factors is then proposed,and a simple formula for the target mean resistance is also presented to avoid iterative computations.Unlike the currently used method,the proposed method can be used to determine load and resistance factors,even when the probability density functions(PDFs)of the basic random variables are not available.Moreover,the proposed method does not require the iterative computation of derivatives or any design points.Thus,the method provides a more convenient and effective way to estimate load and resistance factors in practical engineering applications.Numerical examples are presented to demonstrate the advantages of the proposed third moment method for determining load and resistance factors.

Resistance to chemical attack of bittern-resisting cement in high-bittern environment

A new kind of bittern-resisting cement （BRC） was introduced. This material is based on the ternary cementitious system of clinker containing C4A3 S phase, high-activity ground granulated blast-furnace slag （GGBFS） and fly ash （FA）. The hydration process and the hydrated products of BRC were studied by means of XRD, TG-DTA and SEM, and the resistance to chemical attack of BRC in high-bittern environment was also examined. The corrosion experiment in seven kinds of brines proved that BRC exhibits an excellent resistance to chemical attack of bittern. The corrosion resistance factors were calculated and all of them were greater than 0.96. It showed that BRC totally controls the cement-based material corrosion in brines from four aspects： （1） making full use of the dominant complementation effect of mineral materials; （2） diminishing the hydrated products easy to be attacked; （3） improving the microstructure of hardened cement mortar; （4） degrading the chemical attack of bittern.

Molecular Epidemiological Analysis of Group A Streptococci Isolated from Children in Chaoyang District of Beijing, 2011:emm Types, Virulence Factor Genes and Erythromycin Resistant Genes

Group A streptococcus （GAS） causes a wide range of diseases in the human population. GAS diseases are more common in children than in adults, with clinical manifestations ranging from pharyngitis and impetigo to invasive infections and post streptococcal sequelae, such as acute rheumatic fever and acute post-streptococcal glomerulonephritis[1]. GAS harbors a host of virulence factors that contribute to its complex pathogenicity and differences in the disease severity and frequency. M protein, one of the major virulence factors, is encoded by the emm gene induces a type of specific host immune response and confers antiphagocytic properties.

Stability and water control of nitrogen foam in bulk phase and porous media

Foam is widely used in the petroleum industry thanks to its unique properties and performance. Its application to water control in oil wells has received more and more attention. The stability of nitrogen foam was investigated in pressurized equipment and sand pack. The result indicated that with increasing pressure （0-2 MPa） the stability of foam in the pressurized equipment increased linearly. Increased nitrogen injection pressure caused better dispersion of nitrogen-foaming solution in porous media. The initial residual resistance factor to gas was an exponential function of injection pressure, but the residual resistance factor （to gas and liquid） decreased exponentially with time. The halflife of foam in porous media （expressed in residual resistance factor） was much longer than that in bulk phase （expressed in foam height）. Pore model analysis indicated that good dispersion in porous media and the presence of thick liquid film during dispersion were the main reasons for high stability. Field test indicated that effective residence of foam in the formation not only resulted in much better heat insulation, but also improved steam stimulation by enhancing steam heating.

Bridge pier failure probabilities under combined hazard effects of scour, truck and earthquake. Part Ⅰ: occurrence probabilities

In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials （AASHTO） load and resistance factor design （LRFD） specifications are formulated based on failure probabilities, which are fully calibrated for dead load and nonextreme live loads. Design against earthquake loads is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction （or increased scour depth）. Furthermore, scour effect cannot be linked directly to an LRFD limit state equation, because the latter is formulated using force-based analysis. This paper （in two parts） presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based bridge failure calculations. In Part I of this series, the general principle of treating the scour depth as an equivalent load effect is presented. The individual and combined partial failure probabilities due to truck, earthquake and scour effects are described. To explain the method of including non-force-based natural hazards effects, two types of common scour failures are considered. In Part 11, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load are quantitatively discussed.

Centrifuge experiment on the penetration test for evaluating undrained strength of deep-sea surface soils

Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils,especially surface soils.Significant achievements have been made using full-flow penetration penetrometers to evaluate marine soil strength in the deep penetration;however,a method considering the effect of ambient water on the surface penetration needs to be established urgently.In this study,penetrometers with multiple probes were developed and used to conduct centrifuge experiments on South China Sea soil and kaolin clay.First,the forces on the probes throughout the penetration process were systematically analyzed and quantified.Second,the spatial influence zone was determined by capturing the resistance changes and sample crack development,and the penetration depth for a sample to reach a stable failure mode was given.Third,the vane shear strength was used to invert the penetration resistance factor of the ball and determine the range of the penetration resistance factor values.Furthermore,a methodology to determine the penetration resistance factors for surface marine soils was established.Finally,the effect of the water cavity above various probes in the surface penetration was used to formulate an internal mechanism for variations in the penetration resistance factor.

Towards establishing practical multi-hazard bridge design limit states

In the U.S., the current Load and Resistance Factor Design （LRFD） Specifications for highway bridges is a reliability-based formulation that considers failure probabilities of bridge components due to the actions of typical dead load and frequent vehicular loads. Various extreme load effects, such as earthquake and vessel collision, are on the same reliability-based platform. Since these extreme loads are time variables, combining them with not considered frequent. non- extreme loads is a significant challenge. The number of design limit state equations based on these failure probabilities can be unrealistically large and unnecessary from the view point of practical applications. Based on the opinion of AASHTO State Bridge Engineers, many load combinations are insignificant in their states. This paper describes the formulation of a criterion to include only the necessary load combinations to establish the design limit states. This criterion is established by examining the total failure probabilities for all possible time-invariant and time varying load combinations and breaking them down into partial terms. Then, important load combinations can be readily determined quantitatively,

Bridge pier failure probabilities under combined hazard effects of scour, truck and earthquake. Part Ⅱ: failure probabilities

In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials （AASHTO） load and resistance factor design （LRFD） specifications are formulated based on failure probabilities, which are fully calibrated for dead load and non-extreme live loads. Design against earthquake load effect is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction （or increased scour depth）. Furthermore, scour effect cannot be linked directly to an LRFD limit state equation because the latter is formulated using force-based analysis. This paper （in two parts） presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based failure calculations. In Part I of this series, the general principle for treating the scour depth as an equivalent load effect is presented. In Part II, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load effect are quantitatively discussed. The key formulae of the conditional partial failure probabilities and the necessary conditions are established. In order to illustrate the methodology, an example of dead, truck, earthquake and scour effects on a simple bridge pile foundation is represented.

Corneal biomechanical changes and intraocular pressure in patients with thyroid orbitopathy

AIM：To determine the relevance of the objective parameters addressing the altered biomechanical properties of cornea for glaucoma monitoring in patients with mild or moderate thyroid associated orbitopathy（TAO）,and in healthy individuals.· METHODS：Twenty-five patients with TAO（group 1）and 25 healthy adults（group 2） were included to the study.Both groups were of a similar age and the ratio women：man.For each patient,the following parameters of both eyes were measured with ocular response analyzer（ORA）：corneal hysteresis（CH）,corneal resistance factor（CRF）,Goldmann correlated intraocular pressure（IOPg） and corneal compensated intraocular pressure（IOPcc）.In both groups participating in our study,all measurements were performed within minutes to reduce the diurnal effects.· RESULTS：The mean age in group 1 was 56±11y and76%were women,24%were men.The mean age in group 2 was 64±11y and 68%were women,32%were men.CH correlated negatively with IOPg in group 1（r^2=0.10,P 〈0.05）.IOPg strongly correlated with IOPcc in both groups（group 1：r^2=0.79,P〈0.0001;group 2：r^2=0.85,P〈0.0001）.There was positive correlation between CRF and IOPg in group 1（r^2=0.12,P〈0.05） and in group 2（r^2=0.31,P〈0.0001）.Statistical analysis revealed no significant correlation between CRF and IOPcc in group 1（r^2=0.009,P 〉0.05） and also no significant correlation in group 2（r^2=0.04,P〉0.05）.CRF mean value in group 2（11.51±1.72 mm Hg） was higher than in group 1（10.85±1.45 mm Hg）（P〈0.05）.IOPg strongly correlated with IOPcc in both groups（group 1：r^2=0.79,P〈0.0001;group 2：r^2=0.85,P 〈0.0001）.There was also strong correlation between CRF and CH in both populations：group 1：（r^2=0.58,P〈0.0001）,group 2：（r^2=0.41,P 〈0.0001）.· CONCLUSION：Biomechanical parameters of cornea,as quantified by CH and CRF,and measured together with IOPcc,precisely reveal glaucoma staging in TAO and thus are reliable for diagnosing and follow-up in clinical practice. 〈/tr〉

High-precision Thickness Setting Models for Titanium Alloy Plate Cold Rolling without Tension

Due to its highly favorable physical and chemical properties,titanium and titanium alloy are widely used in a variety of industries.Because of the low output of a single batch,plate cold rolling without tension is the most common rolling production method for titanium alloy.This method is lack of on-line thickness closed-loop control,with carefully thickness setting models for precision.A set of high-precision thickness setting models are proposed to suit the production method.Because of frequent variations in rolling specification,a model structural for the combination of analytical models and statistical models is adopted to replace the traditional self-learning method.The deformation resistance and friction factor,the primary factors which affect model precision,are considered as the objectives of statistical modeling.Firstly,the coefficient fitting of deformation resistance analytical model based on over-determined equations set is adopted.Additionally,a support vector machine（SVM）is applied to the modeling of the deformation resistance and friction factor.The setting models are applied to a 1450 plate-coiling mill for titanium alloy plate rolling,and then thickness precision is found consistently to be within 3%,exceeding the precision of traditional setting models with a self-learning method based on a large number of stable rolling data.Excellent application performance is obtained.The proposed research provides a set of high-precision thickness setting models which are well adapted to the characteristics of titanium alloy plate cold rolling without tension.

Negative regulation of resistance protein-mediated immunity by master transcription factors SARD_1 and CBP60g

Summary Salicylic acid （SA） is an essential defence hormone in plants. Upon pathogen infection, induced biosynthesis of SA is mediated by Isochorismate synthase 1 （ICS1）, whose gene transcription is controlled mainly through two redundant transcription factors, SAR Deficient 1 （SARD0 and Calmodulin- binding protein 6o-like g （CBP60g）.

Studies on Cloning and Transformation of CBF1 Gene of Maize Grass

[Objective]It is revealed whether the similar maize transcriptional activator in CBF1 gene is regulatory cold resistance gene to lay the foundation for breeding new transgenic Forage Maize Varieties with high cold resistance ability.[Methods]In the present paper,the transcriptional factor gene CBF1 was Successfully cloned by PCR from the leaves of Arabidopsis.The sequence was preliminarily analyzed and plant expression vector was constructed.Then with agrobacterium-mediated transgene technique,CBF1 gene was introduced into maize SAUMZ1.[Results]PCR assay revealed that the CBF1 gene was integrated in the maize grass SAUMZ1 genome.Under different low temperature treatment,the relative electrolyte leakage percentage of transgenic plant was lower than Control.[Conclusion] The results showed that the cold-resistance of maize grass SAUMZ1 enhanced after transforming CBF1 gene.

The Study on the Correlation Between Plasma Adiponectin Level and Coronary Heart Disease

Objectives To investigate the relationship between plasma adiponectin level and coronary heart disease （CHD）, and some established cardiovascular risk factors and to probe its probable pathogenesis which adiponectin results in CHD. Methods The levels of plasma adiponectin, fasting plasma insulin （FINS）, C-reactive protein （CRP） and P-selectin were measured by ELISA, plasma ET-1 was measured by radioimmunoassay （RIA） in 75 male patients with CHD and 30 healthy male people. Body mass index （BMI）, waist / hip ratio （WHR） and insulin resistance index （Homa-IR） were calculated respectively. Results （1）The plasma adiponectin levels in CHD group were lower compared with control group[（5.18±2.57）mg / L vs（8.94±2.59）mg / L, P〈 0.001 ], there was no significant difference of plasma adiponectin levels in CHD sub-groups （P 〉 0.05）.（2） Based on multinominal stepwise logistic regression analysis, adiponectin was one of significant and independent risk factors for CHD. （3） Multivariate liner stepwise regression analysis showed that adiponectin had significant correlation with BMI and TG, BMI and TG were independent factors influencing on plasma adiponectin levels. （4） Pearson correlation analysis indicated plasma adiponectin levels were inversely related to FINS levels , Homa-IR, CRP, P-selectin and ET-1. Conclusions （ 1 ）Plasma adiponectin levels are lower in CHD patients compared the control subjects, there are no significant difference of plasma adiponectin levels in patients with SAP, UAP and AMI. （2） Plasma adiponectin levels are relative with CHD. Hypoadiponectinemia is an independent risk factor for CHD. （3）Established cardiovascular risk factors such as BMI and TG have an obvious influence on adiponectin. （4）The probable pathogenesis by which adiponectin involves in CHD is suggested that adiponectin relates to insulin resistance, inflammatory reaction and dysfunction of vessel endothelium.

The geometric resistivity correction factor for several geometrical samples

This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conduc- tivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.

Performance of reliability-based design formats in geotechnical applications

Geotechnical design codes and guidelines are all switching from traditional factor of safety design to modern load and resistance factor design(LRFD)or partial factor design(PFD),in the belief that the latter two bring more flexibility and reliability consistency across various design scenarios,thus produce safe and cost-effective design outcomes.This paper first reviews the LRFD and PFD developed for geotechnical applications.A total of seven methods to calibrate the load and resistance factors are also introduced.The ability of the LRFD and PFD to produce designs with consistent reliability is examined and compared to that of a traditional factor of safety method using two examples of the bearing capacity of strip footings and the global stability of soil nail walls.Results showed that the framework of LRFD offers no apparent advantages over working stress design(WSD)in achieving more consistent reliability for geotechnical structures;the dispersion in design probabilities of failure could be five to seven orders of magnitude difference.The variation will be reduced to three orders if using the PFD.Neither reducing the variability in soil shear strength parameters nor allocating partial resistance factors with respect to soil types would efficiently harmonize the reliability levels when dealing with multiple soil layer conditions.In addition,the uniformity of reliability levels is insensitive to calibrations with or without presetting the load factors.This study provides insights into the LRFD and PFD frameworks currently developed for geotechnical applications.