Target reliability index for serviceability limit state of single piles

The objective is to develop an approach for the determination of the target reliability index for serviceability limit state(SLS) of single piles. This contributes to conducting the SLS reliability-based design(RBD) of piles. Based on a two-parameter,hyperbolic curve-fitting equation describing the load-settlement relation of piles, the SLS model factor is defined. Then, taking into account the uncertainties of load-settlement model, load and bearing capacity of piles, the formula for computing the SLS reliability index(βsls) is obtained using the mean value first order second moment(MVFOSM) method. Meanwhile, the limit state function for conducting the SLS reliability analysis by the Monte Carlo simulation(MCS) method is established. These two methods are finally applied to determine the SLS target reliability index. Herein, the limiting tolerable settlement(slt) is treated as a random variable. For illustration, four load test databases from South Africa are compiled again to conduct reliability analysis and present the recommended target reliability indices. The results indicate that the MVFOSM method overestimates βsls compared to that computed by the MCS method. Besides, both factor of safety(FS) and slt are key factors influencing βsls, so the combination of FS and βsls is welcome to be used for the SLS reliability analysis of piles when slt is determined. For smaller slt, pile types and soils conditions have significant influence on the SLS target reliability indices; for larger slt, slt is the major factor having influence on the SLS target reliability indices. This proves that slt is the most key parameter for the determination of the SLS target reliability index.

Methods, units and quality requirements for the analysis of haemoglobin A_(1c) in diabetes mellitus

The formation of glycohemoglobin, especially the hemoglobin A1c(Hb_(A1c)) fraction, occurs when glucose becomes coupled with the amino acid valine in the β-chain of Hb; this reaction is dependent on the plasma concentration of glucose. Since the early 1970 s it has been known that diabetics display higher values of Hb_(A1c) because they have elevated blood glucose concentrations. Thus Hb_(A1c) has acquired a very important role in the treatment and diagnosis of diabetes mellitus. After the introduction of the first quantitative measurement of Hb_(A1c), numerous methods for glycohemoglobin have been introduced with different assay principles: From a simple minicolumn technique to the very accurate automated highpressure chromatography and lastly to many automated immunochemical or enzymatic assays. In early days, the results of the quality control reports for Hb_(A1c) varied extensively between laboratories, therefore in United States and Canada working groups(WG) of the Diabetes Controls and Complications Trial(DCCT) were set up to standardize the Hb_(A1c) assays against the DCCT/National Glycohemoglobin Standardization Program reference method based on liquid chromatography. In the 1990 s, the International Federation of Clinical Chemistry and Laboratory Medicine(IFCC) appointed a new WG to plan a reference preparation and method for the Hb_(A1c) measurement. When the reference procedureswere established, in 2004 IFCC recommended that all manufacturers for equipment used in Hb_(A1c) assays should calibrate their methods to their proposals. This led to an improvement in the coefficient of variation(CV%) associated with the assay. In this review, we describe the glycation of Hb, methods, standardization of the Hb_(A1c) assays, analytical problems, problems with the units in which Hb_(A1c) values are expressed, reference values, quality control aspects, target requirements for Hb_(A1c), and the relationship of the plasma glucose values to Hb_(A1c) concentrations. We also note that the acceptance of the mmol/mol system for Hb_(A1c) as recommended by IFCC, i.e., the new unit and reference ranges, are becoming only slowly accepted outside of Europe where it seems that expressing Hb_(A1c) values either only in per cent units or with parallel reporting of percent and mmol/mol will continue. We believe that these issues should be resolved in the future and that it would avoid confusion if mmol/mol unit for Hb_(A1c) were to gain worldwide acceptance.

Pigeon-Inspired Circular Formation Control for Multi-UAV System with Limited Target Information

The problem of cooperative circular formation with limited target information for multiple Unmanned Aerial Vehicle(UAV)system is addressed in this paper.A pigeon-inspired circular formation control method is proposed to form the desired circular distribution in a plane based on the intelligent pigeon behavior during hovering.To reach the goal of prescribed radius and angular distribution,the controller is designed consisting of a circular movement part and a formation distribution part.Therein,the circular movement part is designed to make each UAV rotate around the speci-ed circle at the same angular speed only using the relative position between the UAV and the target.The formation distribution part could adjust the angular distance between each UAV and its neighbors with the jointly connected network to reduce communication cost.To smooth the speed variation,nonlinear PID-type method is delivered throughout the evolution of the system.The convergence analysis of the proposed control protocol is presented using Lyapunov theory and graph tools.The e®ectiveness of the proposed control strategies is demonstrated through numerical simulations.