Synthesis, characterization and flocculation performance of zwitterionic copolymer of acrylamide and 4-vinylpyridine propylsulfobetaine

A novel zwitterionic polyacrylamide AMVPPS copolymer containing sulfobetaine groups was synthesized by copolymerizing acrylamide (AM) and 4-vinylpyridine propylsulfobetaine (4-VPPS) in 0.5 mol/L NaCl solution with potassium persulfate (K₂S₂O₈) and sodium bisulfite (NaHSO₃) as initiator. The structure and composition of AMVPPS copolymer were characterized by FT-IR spectroscopy, ¹H NMR and elemental analyses. Thermal stability and solution properties of AMVPPS copolymer were studied by thermogravimetry analysis (TGA) and viscometry. Anti-polyelectrolyte behavior was observed and was found to be enhanced with increasing 4-VPPS content in copolymer. The flocculation performance for 2.5 g/L kaolin suspension and 2.5 g/L hematite suspension was evaluated by transmittance measurement and phase contrast microscopy. The effects of 4-VPPS content in the copolymer, intrinsic viscosity and the added salt on the flocculation performance were investigated. It was found that AMVPPS copolymer was a good flocculant for both anionic kaolin and cationic hematite suspensions and the flocculation performance of copolymer was much better than that of pure polyacrylamide (PAM). A very wide range of the optimum flocculation concentration, named as “flocculation window”, was found for both suspensions. These flocculation characteristics were mainly dependent on the charge neutralization, the intragroup conformation transition from water to NaCl solution and then the interchain bridging of the zwitterionic AMVPPS copolymer.     

Synchronization of inventory and transportation under flexible vehicle constraint: A heuristics approach using sliding windows and hierarchical tree structure

This paper investigates the integrated inventory and transportation planning under flexible vehicle constraint. To offer better services at lower prices, more and more companies turn to outsource transportation functions to other professional service providers, namely 3rd party logistics companies. Under these vehicle rental arrangements, the number of vehicles is a decision variable instead of a fixed number, and the transportation cost includes not only the delivery cost but also the cost of vehicle rental that is proportional to the number of vehicles rented in a given planning horizon. In this paper, the problem is formulated as a mixed integer programming problem. A heuristic algorithm is developed, in which sliding windows are applied to approximate the problem by repeatedly solving a series of overlapping short-term subproblems, and a hierarchical tree structure is used to evaluate the closeness of different groups of retailers. Numerical experiments show that a better tradeoff between the inventory cost and transportation cost can be achieved through the proposed heuristic algorithm.     

用于声表面波滤波器频响旁瓣抑制的修正汉明窗技术

本文提出了一种新技术,可以提高SAW滤波器频响的旁瓣抑制,同传统的标准加权归一化方法相比有三倍的改善。这一技术可以增加3dB带宽,SAW滤波器的输入叉指换能器（IDT）等值加权,而输出叉指换能器具有修正的汉明窗结构。     

EXCEL实用技巧

用简明扼要的语言的ECXEL使用中的具有代表性的疑难问题进行了分析、解答，并介绍了几点很有实用价值的使用技巧。     

高能激光器气动窗口光束质量测量方法探讨

根据参考文献[1]所指出的气动窗口光束质量的评价方法，给出几种与其相配套的光束质量实验测量的实用方法，并对其进行比较分析，同时给出相应的实验结果，为气动窗口的进一步研究提供参考，理论与实验的对比表明，该方法是可行的，并达到了与气动窗口类别无关的评价要求。     

高压下黄铜中追赶稀疏波速度的辐射测量

 用光辐射法、以有机玻璃作窗口测量了143～182 GPa下H62黄铜的追赶稀疏波速度。给出了在对称碰撞下，用透明材料作窗口时，实验确定追赶稀疏波速度的公式。实验结果表明，H62黄铜的冲击熔化点在143～162 GPa之间。     

一维m次多项式实映射的窗口分析

本文利用作者提出的代数分析法［１］首次严格地给出了一维ｍ次多项式实映射的周期Ｎ轨道窗口个数ＭＮ（ｍ）的显式计算公式，并严格地证明了在反对称映射中存在的对称周期２Ｎ轨道的轨道数目ｒ２Ｎ（ｍ）等于通过周期倍分叉产生的周期２Ｎ轨道的轨道β２Ｎ（ｍ）等结论。     

Effects of HC1 annealing of memory oxides on MNOS capacitor memory window

The effect of HC1 annealing of memory oxides of MNOS capacitors on the memory window size and location has been investigated. Both native and thermal oxides were studied. HC1 annealed oxide capacitors exhibit larger memory windows than unannealed capacitors. The largest increase is observed for ±20 volt write/erase pulses. The percent HC1 in the annealing ambient is shown to be a very sensitive parameter in the annealing process. HC1 annealing also causes the center of the memory window to shift toward less negative values of threshold voltage thus reducing the size of the memory window for source-drain protected MNOS devices. This work was supported by the United States Department of Energy and was accomplished while the author was a member of the technical staff at Sandia Laboratories, Albuquerque, New Mexico.     

Estimation in Stationary Markov Renewal Processes,with Application to Earthquake Forecasting in Turkey

Consider a process in which different events occur, with random inter-occurrence times. In Markov renewal processes as well as in semi-Markov processes, the sequence of events is a Markov chain and the waiting distributions depend only on the types of the last and the next event. Suppose that the state-space is finite and that the process started far in the past, achieving stationary. Weibull distributions are proposed for the waiting times and their parameters are estimated jointly with the transition probabilities through maximum likelihood, when one or several realizations of the process are observed over finite windows. The model is illustrated with data of earthquakes of three types of severity that occurred in Turkey during the 20th century.AMS 2000 Subject Classification: 60K20     

Design and Analysis of Built-In Testers for CMOS Switched-Current Circuits

This paper presents the design and analysis of a built-in tester circuit for MOS switched-current circuits used in low-voltage/low-power mixed-signal circuits/systems. The use of the tester can reduce the test length significantly. The developed tester is comprised of a current comparator, a voltage window comparator, and a digital latch. The current comparator is required to have high-accuracy, low-power consumption, simple structure with small chip area, and moderate speed. Results show that the developed current comparator circuit is developed with a small offset current, 0.1 nA, low power consumption, 20 W, and a layout area of 0.01 mm², where the circuit is simulated with the MOSIS SCN 2 m CMOS process parameters and 2 V supply voltage.