Human performance under two different command and control paradigms

The paradoxical behaviour of a new command and control concept called Network Enabled Capability (NEC) provides the motivation for this paper. In it, a traditional hierarchical command and control organisation was pitted against a network centric alternative on a common task, played thirty times, by two teams. Multiple regression was used to undertake a simple form of time series analysis. It revealed that whilst the NEC condition ended up being slightly slower than its hierarchical counterpart, it was able to balance and optimise all three of the performance variables measured (task time, enemies neutralised and attrition). From this it is argued that a useful conceptual response is not to consider NEC as an end product comprised of networked computers and standard operating procedures, nor to regard the human system interaction as inherently stable, but rather to view it as a set of initial conditions from which the most adaptable component of all can be harnessed: the human.     

Size Effects in Thin Face-Centered Cubic Metals for Different Complex Forming Loadings

Influence of the size effects on the mechanical behavior of face-centered cubic metals was studied for complex loadings close to microforming ones. The effect of a reduction in thickness (t) over grain size (d) ratio on the mechanical behavior for high-purity nickel and copper is investigated for three different loadings by tensile and Nakazima tests (plane strain conditions and balanced biaxial expansion). Experimental results highlight a strong degradation of the mechanical properties of Cu and Ni when the t/d ratio is reduced below a critical value, independently of the strain path. However, this effect occurs if the equivalent plastic strain is larger than a critical level which is strain path dependent and related to the stress triaxiality. The current study reveals that plastic anisotropy is also affected by size effects. An excellent correlation is obtained between the t/d ratio and the thickness reduction, through the mean normal plastic anisotropy parameter which is widely used to estimate sheet formability. A size effect map based on forming limit diagrams is proposed to depict the optimal conditions of microforming.     

Study of surface integrity of ground bearing steel using Barkhausen noise technique

An experimental study was undertaken to compare the role of process parameters on the grindability of bearing steel (unhardened and hardened) in conventional grinding domain with particular emphasis on surface integrity. Surface residual stress on the ground specimens has been assessed using X-ray diffraction technique and Barkhausen noise analysis. The aim of this article was to compare the applicability of Barkhausen noise analysis technique to assess the state of residual stress with simultaneous change in microstructure along with the formation of white layer, microhardness, the incorporation of plastic deformation, etc. The results indicate a significant effect of downfeed and work speed on surface integrity parameters like residual stress, microstructure, and microhardness. Residual stress varied in the present work over a domain of 50–700 MPa. Despite simultaneous variation in the microhardness, microstructure, and residual stress during grinding, a linear correlation could be established between Barkhausen noise parameters and residual stress.     

齿轮齿廓淬火与同步双频感应技术

齿轮是现代机械中应用最为广泛的传动零件,它可以转换传动的转向和改变传动的转速.齿轮的传动过程是通过不同的轮齿相互啮合进行的,这就要求齿轮要具有耐冲击、振动及噪音尽量小,强度高,耐磨性好及寿命长.在齿轮的生产过程中需要对齿轮表面轮廓进行热处理,以提高其强度和耐磨性等性能.评价齿轮质量好坏的指标不仅是耐磨性和抗疲劳强度,而且还包括热处理后的变形量.     

Managing risks in public-private partnership formation projects

While sourcing by means of Public-Private Partnerships has been lauded over recent years, increasingly risks appear to jeopardise public organisations' unique societal tasks. Integrated Risk Management has not yet been applied to public organisations getting involved in PPP in the sense of understanding risk management capabilities. This article explores risk awareness and risk management practices underpinning maintenance partnership formation by means of a dual case study of two PPP projects and a short industry survey. The results suggest that organisations face several “intolerable risks” linked to project governance and project management responsibilities: insufficient representation of qualified employees, absence of a shared performance system, assignment of responsibilities and decision-making authority, impractical or inappropriate partnership agreement, and timing of the partnership initiative. Cross-case analysis revealed the role of different levels of risk awareness and senior management involvement. Drawing on these findings, a framework for risk management for PPP formation projects is developed.