David Hume and systems practice

The aim of this paper is to provide some refreshment for jaded and confused spirits. David Hume, the foremost critic of the Enlightenment, asked some questions, pertinent to systems practice, which have yet to be answered fully. His attacks on superstition and naive realism will be received with sympathy today, but he still makes challenges to rationalism and to a priori knowledge and principles, which are as fresh today as they were in his time. He also has some advice for systems practitioners.     

Information technology and systems

Book Review Editorial

Information technology and systems     

COMPETITIVE INVESTMENT STRATEGIES IN ADOPTION OF NEW TECHNOLOGY WITH A FURTHER NEW TECHNOLOGY ANTICIPATED

In dynamic uncertain environments, the investment timing of the firm about adopting the existing new technology is influenced by the rival's actions and technological progress. This paper employs option games approach to present a simplified duopoly continuous time model of technology adoption. In the model, the irreversible investment in adoption of the existing new technology is in strategic competitive circumstances and facing the threat of a further new technology after the competition setting is established. The purpose of the paper is to examine the effect of technological displacement on firms' strategic investment. The results show that rapid displacement of the technology encourages the leader's investment and discourages the follower's investment. Comparing with the optimal timing without the expectation of a further new technology, the firm hastens to invest when no firm has invested; however, once one firm has invested first, the firm will delay its investment. Using mixed strategy analysis,     

Critical considerations in the development of systems thinking and practice

This paper is concerned with the development of ‘Systems Thinking.’ In particular, it considers and critiques ‘traditional Systems Thinking’ within the framework of Critical Systems Thinking. Before embarking on such a venture it is necessary to derive a base context from which to develop argument and analysis. Therefore the outline of this paper is as follows: A contextual setting for Systems Thinking, Theoretical Considerations, Soft Systems Thinking and Methodology, and A Critical Systems Thinking (CST) approach. The account of the development of Systems Thinking is followed by a synopsis of a theoretical framework for Systems Thinking which will allow us to gain an understanding of contemporary views. The paper then goes on to review SSM and CST in order to provide a platform for a critique of traditional forms of Systems Thinking. The final section briefly discusses the applicability of CST to the ‘real-world’ context by outlining some current studies being undertaken by the author.     

Piaget,self-organizing knowledge,and critical systems practice

An examination of Piaget's conception of the source, nature, development, and use of knowledge reveals that his model for the genetic development of human knowledge is cybernetic and self-organizing. Moreover, Piaget presents a model of cognition which is a reflection and extension of autopoietic biological organization; both cognitive and organic systems are seen to exhibit organizational closure and structural plasticity. An action-based intervention method, modeling embedded learning structures as cybernetic, autopoietic systems, may provide insight toward clarifying some theoretical and methodological problems of critical systems thinking.     

一种新型软件设计方法AOP的研究

用传统的方法 (如面向对象方法 ,面向过程方法等 )设计和编写软件时 ,有些设计方案只能通过散乱地分布在各个相关模块中加以实现。从而导致软件的开发过程变得复杂 ,同时也使得代码变得难理解 ,难维护。面向方面编程技术是为较好地解决这一问题而提出的一种新技术。对面向方面编程技术的产生背景、发展过程、编程思想 ,编程语言 ,关键技术及其优点等方面作了综述的详细 ,最后分析了面向方面编程技术的研究应用热点及它的发展前景。     

新分段分数阶混沌系统的同步控制

通过改变修正的Lorenz-Stenflo (modified Lorenz-Stenflo, MLS)混沌系统的分段函数项,得到了一个新的四维分段混沌系统。新系统较MLS混沌系统具有更低的分数阶维数,在3.44阶时仍具有混沌特性。根据分数阶系统的线性稳定性理论和非线性反馈控制方法,提出了新分数阶系统的状态同步方法。通过理论推导,得到了两个混沌系统的同步稳定条件。控制器能够自适应地根据误差大小调节反馈系数,缩短同步时间。最后对3.6阶的分数阶系统进行了同步仿真实验,仿真结果验证了改进算法能够加快同步速度。     

高动态跳频载波跟踪技术

在无人机或导弹等高速运动目标间建立稳定、可靠的通信链路,需要突破高动态下的载波跟踪技术,考虑跳频通信系统的突发传输模式,本文提出基于开环最大似然估计(maximum likelihood estimation,MLE)和扩展卡尔曼滤波跟踪算法的高动态载波信号跟踪技术.通过理论和仿真分析证实了该算法可有效克服传统环路的缺...     

Resistance to change—A monitor of new technology

This paper examines the credibility of the deficit model of resistance to change in a case study on office automation. A functional analysis of resistance to change is conducted using narrative interviews and documentary analysis. Resistance to change is shown to occur and to affect the implementation process: resistance is identified as a useful source of information, directing the attention of the change agency to improve hardware, software, and the organization. User attitudes were found to change: global skepticism developed into critical acceptance of the office system. The decision-making criteria changed during the 3-year period of the case study. More criteria were used, with user-friendliness becoming more prominent in the decision criteria. The case highlights some limitations of Lewinian field theory in studying resistance to change. Systems theory may provide a more useful framework, organized around the principle that resistance to change is a functional selfmonitoring subsystem guiding the internal adjustment of the changing organization and thus securing effectiveness. This approach may have wider implications for the analysis of social change.     

武器装备体系的技术成熟度评估方法

武器装备体系的技术成熟度描述了体系建设的整体技术状态与水平, 在武器装备体系建设管理中是重要的评估与分析内容. 在单项技术成熟度评估的基础上, 建立了装备系统技术成熟度、武器装备体系技术成熟度的评估方法. 通过对武器装备体系技术成熟度评估结果的深入分析, 可以定位体系建设中的瓶颈装备系统与关键技术, 支撑项目管理工作. 所附算例说明了方法的有效性.     

Homologous fault monitoring technology of redundant INS in airborne avionics systems

Redundant technology plays an important role in improving the reliability and fault-tolerance of the airborne avionics systems. A Markov state transition model is introduced to the reliability analysis of the redundant inertial navigation system （RINS） in airborne navigation systems. An information processing mechanism based on difference filtering is put forward to strengthen the consistency between the outputs of the equal-precision inertial navigation system （INS）. On this basis, the homologous fault monitoring algorithm is designed to realize the homologous fault monitoring of RINS. The simulation is carried out based on the above algorithms, and the results verify the effectiveness of the proposed fault monitoring algorithm based on difference filtering. Research results have good reference value for the configuration and design of RINS in airborne integrated avionics systems.     

自适应广义投影同步混沌系统

针对混沌系统的自适应广义投影同步,基于李亚普诺夫稳定性理论,提出设计合适的自适应控制器和参数更新规则。以两个新型的四维混沌系统为例进行数值仿真,实现其驱动系统与响应系统渐近地达到所有状态向量的广义投影同步,同时辨识出系统的所有未知参数。通过数值仿真,证明了所设计的控制器有效性以及理论推导的正确性。     

创新回报不确定性下的新技术采纳研究

考虑到企业在采纳新技术过程中的技术溢出以及新技术创新回报的不确定性,建立生产有差异化产品企业的两阶段博弈模型,以企业采纳时间为分界点分别得出在古诺竞争和伯特兰德竞争两种市场下各个阶段的期望均衡利润,进而对技术创新回报不确定性、企业的最优采纳时间、期望社会福利最大时的企业最优社会采纳时间进行了分析,结果表明,随着创新回报不确定性的增加,先采纳新技术企业的期望利润增加更多;企业间产品差异较大时,领先企业在古诺竞争下的最优采纳时间要比伯特兰德竞争下的最优采纳时间要早;企业间产品差异较小时,领先企业在古诺竞争下的最优采纳时间要晚于伯特兰德竞争下的最优采纳时间.跟随企业在古诺竞争下的最优采纳时间始终早于伯特兰德竞争下的最优采纳时间.     

A new statistical approach for the analysis of uncertain systems

This paper addresses the issues of conservativeness and computational complexity of probabilistic robustness analysis. The authors solve both issues by defining a new sampling strategy and robustness measure. The new measure is shown to be much less conservative than the existing one. The new sampling strategy enables the definition of efficient hierarchical sample reuse algorithms that reduce significantly the computational complexity and make it independent of the dimension of the uncertainty space. Moreover, the authors show that there exists a one to one correspondence between the new and the existing robustness measures and provide a computationally simple algorithm to derive one from the other. This research is supported in part by grants from NASA (NCC5-573), LEQSF (NASA /LEQSF(2001-04)-01), the NNSFC Young Investigator Award for Overseas Collaborative Research (60328304) and a NNSFC grant (10377004).     

空间可修系统的维修性分析、评价与验证技术

随着当前在轨服务技术的快速发展,航天器在轨维修成为了可能。因此,本文系统地定义了空间可修系统(space maintainable system, SMS)的概念,通过梳理维修性分析、评价与验证方法的发展现状,结合SMS系统复杂、在轨维修数据量少等特点,探索性地提出了针对SMS的维修性分析、评价与验证技术。首先利用大量的航天器故障数据,采用基于维修障碍分析法的维修性分析手段。其次,构建了定性评价和基于神经网络的定量评价方案对维修性设计进行评判。最后,考虑SMS真实环境验证样本低等约束,提出了基于贝叶斯理论的小子样维修性验证方法,可以有效地降低试验样本量。     

OFDM协作网络中基于组合叠加导频的信道估计技术

针对三节点放大转发(amplify-and-forward, AF)的正交频分复用(orthogonal frequency division multiplexing, OFDM)协作中继网络,为了高效获取级联和单跳链路信道状态信息(channel state information, CSI),本文提出基于组合叠加导频的信道估计方案。新方案在源节点和中继节点分别将不同的导频叠加到发送数据上,目的节点利用源导频和中继导频分别完成级联(S→R→D)信道和单跳(R→D)信道的估计。为了消除叠加导频方案中信息符号对于各链路信道估计造成的严重干扰,源导频设计采用发端预处理的数据置零叠加导频(data nulling superimposed pilots, DNSP)方式,并提出了基于协作干扰消除(cooperative interference cancelation, CIC)的中继导频设计方案,新方案一方面借助直达(S→D)链路检测符号来消除中继数据对R→D信道估计的影响,另一方面利用迭代重构来弥补源节点数据失真和提高检测性能。仿真结果表明,新方案在避免训练导频占用带宽开销的同时能获得与传统频分复用(frequency division multiplexing, FDM)导频相近的性能。     

The convergence of a new modified BFGS method without line searches for unconstrained optimization or complexity systems

<正> In this paper,a new modified BFGS method without line searches is proposed.Unlike traditionalBFGS method,this modified BFGS method is proposed based on the so-called fixed steplengthstrategy introduced by Sun and Zhang.Under some suitable assumptions,the global convergence andthe superlinear convergence of the new algorithm are established,respectively.And some preliminarynumerical experiments,which shows that the new Algorithm is feasible,is also reported.     

Systems thinking,systems practice,and practical philosophy: A program of research

IfSystems Practice is to serve the cause of socially rational decision making, its understanding of systems approach must open itself up to the communicative dimension of rational practice uncovered by contemporary practical philosophy. This programmatic paper argues that building the bridge between the two traditions of systems thinking and practical philosophy is a key challenge to be faced by the systems community. A three-level framework of rational systems practice is suggested as a point of departure for a program of research.     

Discordant pluralism: A new strategy for critical systems thinking

Systems science is characterised by a huge diversity of theories and practical applications which have arisen since its inception. Each of these theories and ways of practising systems science has legitimate claims for its ability to handle certain kinds of systems problems. Dealing with this diversity can be seen as a critical issue for systems thinking and practice. One approach to handling this rich diversity has been to attempt to capture it in frameworks which align features and positions in a “complementarist” fashion. By reviewing work undertaken by systems thinkers who have advocated such a stance, it will be demonstrated that complementarism has its faults, and can be perceived as an imperialist strategy. A route out of the impasse will be suggested through the use of a form of discordant pluralism, which, if taken up, has the potential for bringing together conflicting perspectives in a new constellation.