Comparison of alternative ACD models via density and interval forecasts: Evidence from the Australian stock market

In this paper a number of alternative autoregressive conditional duration (ACD) models are compared using a sample of data for three major companies traded on the Australian Stock Exchange. The comparison is performed by employing the methodology for evaluating density and interval forecasts, developed by Diebold et al. [F. Diebold, A. Gunther, S. Tay, Evaluating density forecasts with applications to financial risk management, International Economic Review 39 (1998) 863–883] and Christoffersen [P. Christoffersen, Evaluating interval forecasts, International Economic Review 39 (1998) 841–862], respectively. Our main finding is that the generalized gamma and log-normal distributions for the error terms have similar performance and perform better that the exponential and Weibull distributions. Additionally, there seems to be no substantial difference between the standard ACD specification of Engle and Russel [R. Engle, J. Russell, Autoregressive conditional duration: a new model for irregularly-spaced transaction data, Econometrica 66 (1998) 1127–1162] and the log-ACD specification of Bauwens and Giot [L. Bauwens, P. Giot, The logarithmic ACD model: an application to the bid-ask quote process of three NYSE stocks, Annales d’Economie et de Statistique 60 (2000) 117–150].     

Duration time‐series models with proportional hazard

Abstract. The analysis of liquidity in financial markets is generally performed by means of the dynamics of the observed intertrade durations (possibly weighted by price or volume). Various dynamic models for duration data have been considered in the literature, such as the Autoregressive Conditional Duration (ACD) model. These models are often excessively constrained, introducing, for example, a deterministic link between conditional expectation and variance in the case of the ACD model. Moreover, the stationarity properties and the patterns of the stationary distributions are often unknown. The aim of this article is to solve these difficulties by considering a duration time series satisfying the proportional hazard property. We describe in detail this class of dynamic models, discuss its various representations and provide the ergodicity conditions. The proportional hazard copula can be specified either parametrically, or nonparametrically. We discuss estimation methods in both contexts, and explain why they are efficient, that is, why they reach the parametric (respectively, nonparametric) efficiency bound.     

多相测量芯片组省去昂贵的电流互感器

电力公司和消费者希望在较宽的负载范围内得到精确的测量结果,避免因测量误差造成的损失。如今,典型的一级仪表要求的电流测量范围为1000：1或更高,这就要求电表测量的功率侑邑量误差必须低于1％,对测量IC的要求则更高,如一级仪表要求测量IC的典型误差容限小于0.3％。由于交流电源电压的变化范围很少超过10％,     

交互式语音应答系统的实现方法

为高效、快速地构建小型呼叫中心系统,基于CTI技术,依据有限状态机的编程理论,设计了交互式语音应答方案,给出了基本流程图并用VB实现了程序编写、主程序运行界面.通过理论分析、系统设计及运行实践,证实该方案有较好的实用性、可行性,且程序运行具有高的稳定性、灵活的可扩展性.     

基于SIP的远程呼叫中心的设计方案

呼叫中心是指通过互动式语音应答和人工坐席通信为客户提供协助和咨询的交互式增值服务的系统。传统的呼叫中心更多的依赖于硬件实现,且不易扩展。此文提出了一种基于SIP协议的呼叫中心,与传统的基于CTI技术的呼叫中心相比,有更好的扩展性和灵活性;同时此系统可以通过Internet网络传输远程呼叫大大节省了通话费用。     

呼叫中心系统技术的应用研究

本系统研究呼叫中心系统组成、功能及关键技术,并分析ACD、CTI、IVR等呼叫中心主要部件.结合系统工作原理,对比讨论了三种业界主流的呼叫中心实现技术:基于交换机的呼叫中心、基于板卡的呼叫中心、基于网络电话或网络交换机(IP-PBX)的呼叫中心.     

关于铝电解槽控制极距调整策略存在的问题及解决方案

论述了电解槽极距控制存在的问题,通过对当前电解槽控制极距调整策略的分析及问题确认,实施了新的控制调整策略。通过对槽控机关于极距控制基础分析、影响因素、调整方案三个方面的分析描述,提出解决办法,确保极距控制效果。     

铝电解槽关键极节能技术研究

在分析铝电解槽传统节能技术不足的基础上,提出了关键极节能新技术.对关键极节能技术的实施步骤及其应用情况进行了全面分析,开发了一套在低极距生产条件下新操作工艺制度.从应用情况看,得到以下结论:应用关键极节能技术实施后,可达到阳极电流分布和极距分布更加合理、铝液波动更加平稳的节能目的.     

基于H.323网守的呼叫中心模型设计

通过对当前呼叫中心模型和Ｈ．３２３网络及其网守的分析,提出了一种新的基于Ｈ?３２３网守的呼叫中心模型。     

Rounding Out the Understanding of ACD Toxicity with the Discovery of Cyclic Forms of Actin Oligomers

Actin is an essential element of both innate and adaptive immune systems and can aid in motility and translocation of bacterial pathogens, making it an attractive target for bacterial toxins. Pathogenic Vibrio and Aeromonas genera deliver actin cross-linking domain (ACD) toxin into the cytoplasm of the host cell to poison actin regulation and promptly induce cell rounding. At early stages of toxicity, ACD covalently cross-links actin monomers into oligomers (AOs) that bind through multivalent interactions and potently inhibit several families of actin assembly proteins. At advanced toxicity stages, we found that the terminal protomers of linear AOs can get linked together by ACD to produce cyclic AOs. When tested against formins and Ena/VASP, linear and cyclic AOs exhibit similar inhibitory potential, which for the cyclic AOs is reduced in the presence of profilin. In coarse-grained molecular dynamics simulations, profilin and WH2-motif binding sites on actin subunits remain exposed in modeled AOs of both geometries. We speculate, therefore, that the reduced toxicity of cyclic AOs is due to their reduced configurational entropy. A characteristic feature of cyclic AOs is that, in contrast to the linear forms, they cannot be straightened to form filaments (e.g., through stabilization by cofilin), which makes them less susceptible to neutralization by the host cell.