Emission cross section and fluorescence efficiency of Nd-pentaphosphate

The room-temperature cross sections for the Nd³⁺⁴F_{3/2}levels to the⁴I_{11/2}and⁴I_{9/2}manifolds (lower laser state and ground state, respectively) in NdP5O14are measured by two spectroscopic methods. A value for the largest cross section ofsigma(R_{1} - Y_{2}) = 1.7 times 10^{-19}cm²is found. The highest effective cross section, resulting from superposition of two lines at 1.051 μm, gives a laser gain per Nd ion which is about 2/3 of the maximum gain in YAG:Nd. The relative branching ratio into the⁴I_{11/2}and⁴I_{9/2}manifolds is 0.65:0.35. Comparison of the integrated cross sections with the measured lifetime for 1-percent Nd in LaP5O14indicates a combined efficiency <0.1 for the remaining transitions, namely radiative decay into the⁴I_{13/2}and⁴I_{15/2}manifolds and multiphonon quenching. A measurement of temperature dependence of fluorescence lifetime supports this last result.     

Application of the theory of optimal experiments to adaptive electromagnetic-induction sensing of buried targets

A mobile electromagnetic-induction (EM I) sensor is considered for detection and characterization of buried conducting and/or ferrous targets. The sensor maybe placed on a robot and, here, we consider design of an optimal adaptive-search strategy. A frequency-dependent magnetic-dipole model is used to characterize the target at EMI frequencies. The goal of the search is accurate characterization of the dipole-model parameters, denoted by the vector /spl Theta/; the target position and orientation are a subset of /spl Theta/. The sensor position and operating frequency are denoted by the parameter vector p and a measurement is represented by the pair (p, O), where O denotes the observed data. The parameters p are fixed for a given measurement, but, in the context of a sequence of measurements p may be changed adaptively. In a locally optimal sequence of measurements, we desire the optimal sensor parameters, p/sub N+1/ for estimation of /spl Theta/, based on the previous measurements (p/sub n/, O/sub n/)/sub n=1,N/. The search strategy is based on the theory of optimal experiments, as discussed in detail and demonstrated via several numerical examples.     

Synthesis and biocompatibility of porous nano-hydroxyapatite/collagen/alginate composite

Porous nano-hydroxyapatite/collagen/alginate (nHAC/Alginate) composite containing nHAC and Ca-crosslinked alginate is synthesized biomimetically. This composite shows a significant improvement in mechanical properties over nHAC material. Mechanical test results show that the compressive modulus and yield strength of this composite are in direct proportion to the percentage of Ca-crosslinked alginate in the composite. Primary biocompatibility experiments in vitro including fibroblasts and osteoblasts co-culture with nHAC/alginate composite indicated the high biocompatibility of this composite. Therefore the composite can be a promising candidate of scaffold material for bone tissue engineering.     

数字区调新技术新方法—RS_OrthoMapper系统研制开发

为了适应当今数字区调工作的需要,开发一套3S技术有机结合简单实用的数字区调野外工作平台或软件系统,已成为燃眉之急。论文介绍了数字区调新技术新方法--RS_OrthoMapper系统研制与开发的基本需求、系统的总体结构与设计、系统实现等,并给出了系统中一些重要的逻辑视图。该系统在西藏昌务场和青海阿拉克湖等地区数字区调填图中示范应用,获得良好效果。     

Determination of alkylbenzyldimethylammonium chlorides in river water and sewage effluent by solid-phase extraction and gas chromatography/mass spectrometry

This study presents a modified method to analyze alkylbenzyldimethylammonium chlorides (ABDACs) in river water and sewage effluent. The method involves mixed samples with linear alkylbenzenesulfonates (LAS) as a counterion to enhance the extraction of ABDAC residues from an RP-18 solid-phase cartridge by formation of hydrophobic ion-pair complexes. The ABDACs were then eluted with methanol-ethyl acetate (1:1, v/v) and formed to their corresponding alkyldimethylamines by the Hofmann degradation with potassium tert-butoxide. The alkyldimethylamines were then identified and quantitated by gas chromatograph/mass spectrometry (GC/MS). The results indicate that, in the presence of LAS, debenzylation of ABDACs occurs selectively at a temperature higher than 90 degrees C to produce the corresponding nonionic alkyldimethylamines. The method proposed herein provides a high precision and sensitivity for ABDACs, to quantitation at < or =0.1 microg/L in 500 mL of the water samples. The average recovery of ABDAC spiked water samples was 95% with relative standard deviations (RSD, n = 7) of 9%. The RSDs of three replicate environmental sample analyses ranged from 5 to 11%. Direct HPLC method was applied to evaluate the GC/MS method, and compatible results were observed.     

A variable neighborhood search for minimizing single machine weighted earliness and tardiness with common due date

Although the concept of just-in-time (JIT) production systems has been proposed for over two decades, it is still important in real-world production systems. In this paper, we consider minimizing the total weighted earliness and tardiness with a restrictive common due date in a single machine environment, which has been proved as an NP-hard problem. Due to the complexity of the problem, metaheuristics, including simulated annealing, genetic algorithm, tabu search, among others, have been proposed for searching good solutions in reasonable computation times. In this paper, we propose a hybrid metaheuristic that uses tabu search within variable neighborhood search (VNS/TS). There are several distinctive features in the VNS/TS algorithm, including different ratio of the two neighborhoods, generating five points simultaneously in a neighborhood, implementation of the B/F local search, and combination of TS with VNS. By examining the 280 benchmark problem instances, the algorithm shows an excellent performance in not only the solution quality but also the computation time. The results obtained are better than those reported previously in the literature.     

On Bandwidth-Efficient Overlay Multicast

In this paper, we propose a new multicast delivery mechanism for bandwidth-demanding applications in IP networks. Our mechanism, referred to as multiple-destination overlay multicast (MOM), combines the advantages of IP multicast and overlay multicast. We formulate the MOM routing problem as an optimization problem. We then design an algorithm based on Lagrangian relaxation on our formulation and propose a distributed protocol based on the algorithm. For network operators, MOM consumes less network bandwidth than both IP multicast and overlay multicast. For users, MOM uses less interface bandwidth than overlay multicast.     

Decision support for risk analysis on dynamic alliance

Dynamic alliance has been considered a temporary organization of member enterprises formed to pool their core competencies and exploit fast changing market opportunities. Although many problems on dynamic alliance such as partner selection, operation management, information exchanges and their standards, etc., have been investigated, the risk management of dynamic alliance has not received deserved attention until now. For risk evaluation is the most important phase of risk management, so this paper is mainly concerned with the risk evaluation problem. Various kinds of risk factors that affect the operation of alliance are identified, and their levels are measured by three parameters such as risk occurrence likelihood, consequence severity and risk control degree. These parameters are expressed by trapezoidal fuzzy numbers. Furthermore, risk evaluation is regarded as a multiattribute decision-making (MADM) problem with uncertainty. A new evaluation approach based on the framework of the evidential reasoning (ER) is proposed. Finally, a numerical example is given to illustrate the application of this approach in the process of risk evaluation.     

线性流形上一类矩阵方程的最佳逼近问题

本文研究矩阵方程AXB=C在线性流形Γ={X∈SR~(n×n)|||TX-Y||=min}上的最佳逼近问题,得到了问题解的表达式．此外,还给出了求解该问题的数值算法和算例．