Quantifying requirements volatility effects

In an organization operating in the bancassurance sector we identified a low-risk IT subportfolio of 84 IT projects comprising together 16,500 function points, each project varying in size and duration, for which we were able to quantify its requirements volatility. This representative portfolio stems from a much larger portfolio of IT projects. We calculated the volatility from the function point countings that were available to us. These figures were aggregated into a requirements volatility benchmark. We found that maximum requirements volatility rates depend on size and duration, which refutes currently known industrial averages. For instance, a monthly growth rate of 5% is considered a critical failure factor, but in our low-risk portfolio we found more than 21% of successful projects with a volatility larger than 5%. We proposed a mathematical model taking size and duration into account that provides a maximum healthy volatility rate that is more in line with the reality of low-risk IT portfolios. Based on the model, we proposed a tolerance factor expressing the maximal volatility tolerance for a project or portfolio. For a low-risk portfolio its empirically found tolerance is apparently acceptable, and values exceeding this tolerance are used to trigger IT decision makers. We derived two volatility ratios from this model, the π-ratio and the ρ-ratio. These ratios express how close the volatility of a project has approached the danger zone when requirements volatility reaches a critical failure rate. The volatility data of a governmental IT portfolio were juxtaposed to our bancassurance benchmark, immediately exposing a problematic project, which was corroborated by its actual failure. When function points are less common, e.g. in the embedded industry, we used daily source code size measures and illustrated how to govern the volatility of a software product line of a hardware manufacturer. With the three real-world portfolios we illustrated that our results serve the purpose of an early warning system for projects that are bound to fail due to excessive volatility. Moreover, we developed essential requirements volatility metrics that belong on an IT governance dashboard and presented such a volatility dashboard.     

西门子数字输入中断模块的应用研究

介绍了如何在STEP7中配置西门子数字输入中断模块,如何进行软件中断处理,对中断标志位识别和常见编程处理给出了详细的描述.     

开卷机钢卷直径计算优化算法在带钢纵剪生产线中的应用

在带钢纵剪生产线的电气控制系统中,开卷机的钢卷卷径（以下简称卷径）是一个重要的检测参数,其检测和计算的准确性对系统的控制精度影响很大。本文介绍了一种适用于纵剪生产线开卷卷径的测量与计算方法,并且简要说明了如何通过西门子S7-400PLC来实现。经过实际的生产运行证明,该方法可以提高开卷机的实际卷径精度,增强测控系统的稳定性和可靠性。     

T400工艺板在飞剪电控系统改造中的应用

本文在起停式飞剪的电控系统改造中,采用基于T400工艺模块的分级分布式计算机控制系统,建立了控制系统的数学模型,并针对该控制系统进行了MATLAB仿真。仿真结果表明,该控制系统设计合理,调节系统的动、静态特性较好。     

混凝土养护期间HRB400钢筋钝化行为研究

为了研究HRB400钢筋在模拟养护阶段混凝土孔隙液中表面钝化膜的生长过程,采用3种电化学测试技术(开路电位、电化学阻抗谱、动电位极化曲线)研究钢筋表面钝化膜的性能随着浸泡时间的变化特征,此外通过XPS对稳定钝化膜的成分与结构进行分析。结果表明,同传统钢筋材料一样,HRB400钢筋在模拟混凝土养护条件的溶液中展现出良好的耐蚀性能,浸泡5 d后便能够生成稳定钝化膜。XPS分析发现钢筋钝化膜为双层结构,内层以二价铁离子化合物为主,外层主要由三价铁离子化合物组成。     

基于西门子S7—400PLC的包钢转炉自动化系统设计与实现

该文针对包钢220吨转炉设计并实现了一套完整的自动控制系统。主要介绍了该系统的结构与硬件配置以及对所采用的软件的评估,还就系统中的数据通信、氧枪定位、汽包三冲量调节、系统的监控等问题进行了讨论,并详细分析了有关控制回路的调试和实施。     

Parameterized complexity of control problems in Maximin election

Elections are a central model in a variety of areas. This paper studies parameterized computational complexity of five control problems in the Maximin election. We obtain the following results: constructive control by adding candidates is W[2]-hard with respect to the parameter “number of added candidates”; both constructive and destructive control by adding/deleting voters are W[1]-hard with respect to the parameter “number of added/deleted voters”.     

西门子S7系列PLC在成都地铁BAS系统中的应用

本系统以西门子S7-414H冗余控制器为主站,多台S7—200PLC和S7—300PLC为从站,通过光纤链路模块OLM组成冗余光纤环网,实现地铁设备监控系统的完美控制。文章重点介绍了控制工艺背景、主／从网络组成构架、硬件配置及软件编程．要点、系统中包含的PROFIBUS-DP、MODBUS、网络读写等通讯协议出现的问题及解决方法、调试后达到的效果及应用体会。     

冗余控制系统在炼铁厂TRT发电装置中的应用

鉴于TRT高炉煤气发电装置的重要性且对其可靠性的要求较高,因而该发电装置的控制系统选用了西门子S7—400H冗余系统。文中简述了TRT高炉煤气发电装置的构成,介绍了S7—400H冗余系统的硬件结构、模块参数和各程序模块的具体功能。该控制系统投运后,TRT高炉煤气发电装置运行可靠,效果良好。     

The cascaded nature of lexical selection and integration in auditory sentence processing.

An event-related brain potential experiment was carried out to investigate the temporal relationship between lexical selection and the semantic integration in auditory sentence processing. Participants were presented with spoken sentences that ended with a word that was either semantically congruent or anomalous. Information about the moment in which a sentence-final word could uniquely be identified, its isolation point (IP), was compared with the onset of the elicited N400 congruity effect, reflecting semantic integration processing. The results revealed that the onset of the N400 effect occurred prior to the IP of the sentence-final words. Moreover, the factor early or late IP did not affect the onset of the N400. These findings indicate that lexical selection and semantic integration are cascading processes, in that semantic integration processing can start before the acoustic information allows the selection of a unique candidate and seems to be attempted in parallel for multiple candidates that are still compatible with the bottom-up acoustic input. (PsycINFO Database Record (c) 2010 APA, all rights reserved)