The influence of the relative phase between the driving voltages on electron heating in asymmetric dual frequency capacitive discharges

The influence of the relative phase between the driving voltages on electron heating in asymmetric phase-locked dual frequency capacitively coupled radio frequency plasmas operated at 2 and 14 MHz is investigated. The basis of the analysis is a nonlinear global model with the option to implement a relative phase between the two driving voltages. In recent publications it has been reported that nonlinear electron resonance heating can drastically enhance the power dissipation to electrons at moments of sheath collapse due to the self-excitation of nonlinear plasma series resonance (PSR) oscillations of the radio frequency current. This work shows that depending on the relative phase of the driving voltages, the total number and exact moments of sheath collapse can be influenced. In the case of two consecutive sheath collapses a substantial increase in dissipated power compared with the known increase due to a single PSR excitation event per period is observed. Phase resolved optical emission spectroscopy (PROES) provides access to the excitation dynamics in front of the driven electrode. Via PROES the propagation of beam-like energetic electrons immediately after the sheath collapse is observed. In this work we demonstrate that there is a close relation between moments of sheath collapse, and thus excitation of the PSR, and beam-like electron propagation. A comparison of simulation results to experiments in a single and dual frequency discharge shows good agreement. In particular the observed influence of the relative phase on the dynamics of a dual frequency discharge is described by means of the presented model. Additionally, the analysis demonstrates that the observed gain in dissipation is not accompanied by an increase in the electrode’s dc-bias voltage which directly addresses the issue of separate control of ion flux and ion energy in dual frequency capacitively coupled radio frequency plasmas.

Assessment framework for construction supply chain relationships: Development and evaluation

The change of supply chain relationships from the traditional adversarial to the collaborative has been increasing in the UK construction industry. To reflect this change, some attempts have been made to establish models for measuring and improving supply chain relationships in construction. However, there are obvious deficiencies in these existing models. This highlights the need for a systematic model for the assessment of construction supply chain relationships. Based on a review of the literature and an expert group discussion, an assessment framework is developed in this paper, which consists of assessment criteria, relationship levels, detailed descriptions, assessment classes and assessment procedures. The proposed framework is evaluated through expert interviews and case studies. This framework provides a roadmap for the improvement of supply chain relationships. It can help construction organisations to position their current relationship and identify key areas for relationship improvement in the future.

Maturity Model for Supply Chain Relationships in Construction

This study explores the special characteristics of the construction industry and develops a maturity model for measuring and improving the relationships between the key players of a construction supply chain. The model adopts the capability maturity methodology and defines four maturity levels of construction supply chain relationships. It is in a matrix format, consisting of 24 assessment criteria in eight categories at each maturity level. It also provides three different ways of using the model. The model is evaluated through a series of expert interviews. A case study is also presented to demonstrate the application of this model in practice.

Experiences with mephedrone pre- and post-legislative controls: Perceptions of safety and sources of supply

Background: Drug scenes within several countries have changed in recent years to incorporate a range of licit psychoactive products, collectively known as “legal highs.” Hundreds of different legal high products have been described in the literature. Many of these products contain synthetic stimulants that allegedly
“mirror” the effects of some illicit drugs. In 2009–2010, growing concern by the UK and Irish governments focused on mephedrone, a synthetic stimulant that had become embedded within several drug scenes in Britain and Ireland. In April 2010, mephedrone and related cathinone derivatives were banned under
the UK’s Misuse of Drugs Act 1971. Setting aside “worse case scenarios” that have been portrayed by UK and Irish media, little is known about mephedrone use from the consumer’s perspective. The purpose of this paper was to (1) explore respondents’ experiences with mephedrone, (2) examine users’ perceptions
about the safety of mephedrone, and primarily to (3) examine sources of mephedrone supply during the pre- and post-ban periods.
Methods: Semi-structured interviews were conducted with 23 adults who had used mephedrone during 2009–2010. Data collection occurred in May and June 2010, following the ban on mephedrone. A total of 20/23 respondents had used mephedrone during the post-ban period, and the vast majority had prior
experience with ecstasy or cocaine. Respondents’ ages ranged from 19 to 51, approximately half of the sample were female and the majority (19 of 23) were employed in full- or part-time work.
Results: Most respondents reported positive experiences with mephedrone, and for some, the substance emerged as a drug of choice. None of the respondents reported that the once-legal status of mephedrone implied that it was safe to use. Very few respondents reported purchasing mephedrone from street-based
or on-line headshops during the pre-ban period, and these decisions were guided in part by respondents’ attempts to avoid “drug user” identities. Most respondents purchased or obtained mephedrone from friends or dealers, and mephedrone was widely available during the 10-week period following the ban. Respondents reported a greater reliance on dealers and a change in mephedrone packaging following the criminalisation of mephedrone.
Conclusion: The findings are discussed in the context of what appears to be a rapidly changing mephedrone market. We discuss the possible implications of criminalising mephedrone, including the potential displacement effects and the development of an illicit market.

Establishing ex ante public construction supply chain guidelines in the public procurement of Schools' estate

Purpose – The purpose of this study is to explore the formative development of construction supply chain guidelines or proposals in a UK region’s schools’ estates procurement process to more effectively address a forthcoming increase in investment.

Design/methodology/approach – The research approach is interpretive. Using an action research approach, repeated semi-structured interviews and focus groups with a range of stakeholders are conducted.

Findings – The current construction supply chain in schools’ estate procurement has many difficulties, not least given the highly fragmented and disconnected nature of the projects. Synergies are being missed and there is little or no continuous improvement. Drawing on these findings, the research iteratively develops a range of proposals and guidelines to address this situation.

Research limitations/implications – This research adds weight to the current focus on pressing for change in the construction industry. It presents potentially valuable insights into the benefits of partnering arrangements and how these might usefully be incorporated into schools’ estate supply chain.

Practical implications – A set of guidelines is developed to guide the public procurement of schools’ estate in a UK region. These guidelines are set within the context of the Modernising and Rethinking Construction agenda.

Originality/value – The action research approach enabled the researchers to gain a unique insight into how public procurement and contractor personnel interact and to establish effective practical guidelines.

Soil resource supply influences faunal size-specific distributions in natural food webs

The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to the entire community is high under low soil phosphorus content and causes shifts in the mass-abundance relationships and in the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according to resource availability and can predict environmental shifts in ecologically meaningful ways.

The Effect of Risk Sensitivity on Collaborative New Product Development in a Supply Chain

The increasing risks and costs of new product development require firms to collaborate with their supply chain partners in product management. In this paper, a supply chain model is proposed with one risk-neutral supplier and one risk-averse manufacturer. The manufacturer has an opportunity to enhance demand by developing a new product, but both the actual demand for new product and the supplier’s wholesale price are uncertain. The supplier has an incentive to share risks of new product development via an advance commitment to wholesale price for its own profit maximization. The effects of the manufacturer’s risk sensitivity on the players’ optimal strategies are analyzed and the trade-off between innovation incentives and pricing flexibility is investigated from the perspective of the supplier. The results highlight the significant role of risk sensitivity in collaborative new product development, and it is found that the manufacturer’s innovation level and retail price are always decreasing in the risk sensitivity, and the supplier prefers commitment to wholesale price only when the risk sensitivity is below a certain threshold.

Critical Success Factors for Transfer-Operate-Transfer Urban Water Supply Projects in China

Over the years, build-operate-transfer (BOT) has continuously attracted research interests. Many studies on BOT have been carried out. Variations of BOT such as build-own-operate-transfer and build-own-operate have also been reported in some relevant publications. However, few investigations thus far have been conducted for transfer-operate-transfer (TOT). Therefore, there is a knowledge gap in this particular field. TOT is a new model that is suitable for existing infrastructure and public utility projects formerly funded by the governments and currently operated by state-owned enterprises. It refers to the transfer of a running public project to a foreign business or domestic private entity. Based on four case studies carried out in the Chinese water supply industry, this paper examines why there is an increasing need for TOT projects and identifies the distinctive features of TOT practice in China. This is followed by an introduction of a framework of critical success factors (CSFs) for TOT projects. The most important factors include project profitability, asset quality, fair risk allocation, competitive tendering, internal coordination within government, employment of professional advisors, corporate governance, and government supervision. The identification of CSFs provides a useful guidance to project parties planning to participate in TOT practice.

Drivers of Supply Network Governance: An Explorative Study of the Dutch Chemical Industry.

The authors identify a number of drivers of supply network governance, a widely appraised governance form aimed at reaping the benefits of both vertical integration and market exchange. Case studies conducted in the Dutch chemical industry are used to explore these drivers. The findings identify interdependence of organizational activities and asset-specific investments as the key drivers of supply network governance in the chemical industry. Firms enjoy relational rents and tend to share knowledge in supply network relationships, however these factors seem to strengthen supply network relationships rather than create them.