An absorptive capacity interpretation of Six Sigma

Purpose – The Six Sigma approach to business improvement has emerged as a phenomenon in both the practitioner and academic literature with potential for achieving increased competitiveness and contributing. However, there is a lack of critical reviews covering both theory and practice. Therefore, the purpose of this paper is to critically review the literature of Six Sigma using a consistent theoretical perspective, namely absorptive capacity.

Design/methodology/approach – The literature from peer-reviewed journals has been critically reviewed using the absorptive capacity framework and dimensions of acquisition, assimilation, transformation, and exploitation.

Findings – There is evidence of emerging theoretical underpinning in relation to Six Sigma borrowing from an eclectic range of organisational theories. However, this theoretical development lags behind practice in the area. The development of Six Sigma in practice is expanding mainly through more rigorous studies and applications in service-based environments (profit and not for profit). The absorptive capacity framework is found to be a useful overarching framework within which to situate existing theoretical and practice studies.

Research limitations/implications – Agendas for further research from the critical review, in relation to both theory and practice, have been established in relation to each dimension of the absorptive capacity framework.

Practical implications – The paper shows that Six Sigma is both a strategic and operational issue and that focussing solely on define, measure, analyse, improve control-based projects can limit the strategic effectiveness of the approach within organisations.

Originality/value – Despite the increasing volume of Six Sigma literature and organisational applications, there is a paucity of critical reviews which cover both theory and practice and which suggest research agendas derived from such reviews.

Low SNR Capacity for MIMO Rician and Rayleigh-Product Fading Channels with Single Co-channel Interferer and Noise

This paper studies the ergodic capacity of multiple-input multiple-output (MIMO) systems with a single co-channel interferer in the low signal-to-noise-ratio (SNR) regime. Two MIMO models namely Rician and Rayleigh-product channels are investigated. Exact analytical expressions for the minimum energy per information bit, Eb/N0min, and wideband slope, S0, are derived for both channels. Our results show that the minimum energy per information bit is the same for both channels while their wideband slopes differ significantly. Further, the impact of the numbers of transmit and receive antennas, the Rician K factor, the channel mean matrix and the interference-to-noise-ratio (INR) on the capacity, is addressed. Results indicate that interference degrades the capacity by increasing the required minimum energy per information bit and reducing the wideband slope. Simulation results validate our analytical results.

Harnessing the slipstream: building educational research capacity in Northern Ireland. Size matters

Northern Ireland is uniquely distinguished from England, Scotland and Wales, by being a society in transition, emerging from a prolonged period of civil conflict and political instability that has affected its infrastructure and has increased the need for co-ordinated and specialist research. The paper traces some of the systemic challenges and opportunities for educational research capacity-building that arise from Northern Ireland being uniquely positioned as a small polity and critically appraises how initiatives elsewhere, while providing valuable exemplars, are unlikely to transfer readily to this context. Rather, building on an expanded definition of research capacity, Northern Ireland needs to capitalize cautiously on the current climate of openness between policymaker and researcher communities to develop a shared, cohesive agenda, improve research support and harness the strengths and pockets of excellence that exist. All of these should simultaneously go towards meeting local priority research needs, addressing the developmental capacity building needs of local researcher, while at the same time contributing to local, national and international knowledge production.

Absolute photoionization cross sections for Xe4+, Xe5+, and Xe6+ near 13.5 nm: Experiment and theory

Absolute photoionization cross-section measurements for a mixture of ground and metastable states of Xe4+, Xe5+, and Xe6+ are reported in the photon energy range of 4d -> nf transitions, which occur within or adjacent to the 13.5 nm window for extreme ultraviolet lithography light source development. The reported values allow the quantification of opacity effects in xenon plasmas due to these 4d -> nf autoionizing states. The oscillator strengths for the 4d -> 4f and 4d -> 5f transitions in Xeq+ (q=1-6) ions are calculated using nonrelativistic Hartree-Fock and random phase approximations. These are compared with published experimental values for Xe+ to Xe3+ and with the values obtained from the present experimental cross-section measurements for Xe4+ to Xe6+. The calculations assisted in the determination of the metastable content in the ion beams for Xe5+ and Xe6+. The experiments were performed by merging a synchrotron photon beam generated by an undulator beamline of the Advanced Light Source with an ion beam produced by an electron cyclotron resonance ion source.

Capacity and resource allocation of cooperative MIMO in ad hoc networks

Cooperative MIMO (Multiple Input–Multiple Output) allows multiple nodes share their antennas to emulate antenna arrays and transmit or receive cooperatively. It has the ability to increase the capacity for future wireless communication systems and it is particularly suited for ad hoc networks. In this study, based on the transmission procedure of a typical cooperative MIMO system, we first analyze the capacity of single-hop cooperative MIMO systems, and then we derive the optimal resource allocation strategy to maximize the end-to-end capacity in multi-hop cooperative MIMO systems. The study shows three implications. First, only when the intra-cluster channel is better than the inter-cluster channel, cooperative MIMO results in a capacity increment. Second, for a given scenario there is an optimal number of cooperative nodes. For instance, in our study an optimal deployment of three cooperative nodes achieve a capacity increment of 2 bps/Hz when compared with direct transmission. Third, an optimal resource allocation strategy plays a significant role in maximizing end-to-end capacity in multi-hop cooperative MIMO systems. Numerical results show that when optimal resource allocation is applied we achieve more than 20% end-to-end capacity increment in average when compared with an equal resource allocation strategy.

Maximizing the Localized Relaxation: The Origin of the Outstanding Oxygen Storage Capacity of kappa-Ce2Zr2O8

Pretty vacant: The excellent oxygen storage capacity (OSC) of ?-Ce2Zr2O8 (see picture; Ce gray, Zr green, O red) is shown to be a result of its unique structural features; after removing oxygen atoms, the structural relaxation is local (vacancy shown in brown), and both the localized structural relaxation and the number of localized structural relaxations are maximized.

MEASUREMENT AND CALCULATION OF ABSOLUTE SINGLE AND MULTIPLE CHARGE EXCHANGE CROSS SECTIONS FOR Feq+ IONS IMPACTING H2O

Charge exchange (CE) plays a fundamental role in the collisions of solar- and stellar-wind ions with lunar and planetary exospheres, comets, and circumstellar clouds. Reported herein are absolute cross sections for single, double, triple, and quadruple CE of Feq+ (q = 5-13) ions with H2O at a collision energy of 7q keV. One measured value of the pentuple CE is also given for Fe9+ ions. An electron cyclotron resonance ion source is used to provide currents of the highly charged Fe ions. Absolute data are derived from knowledge of the target gas pressure, target path length, and incident and charge-exchanged ion currents. Experimental cross sections are compared with new results of the n-electron classical trajectory Monte Carlo approximation. The radiative and non-radiative cascades following electron transfers are approximated using scaled hydrogenic transition probabilities and scaled Auger rates. Also given are estimates of cross sections for single capture, and multiple capture followed by autoionization, as derived from the extended overbarrier model. These estimates are based on new theoretical calculations of the vertical ionization potentials of H2O up to H2O10+.