Integration of HSQ in the direct-on-metal approach for 0.25-μm technology

The spin-on low-k material coated directly on the metal lines, which is called the direct-on-metal (DOM) approach, has been investigated with respect to issues about the intraline capacitance, the intraline leakage current, metal corrosion, unlanded vias, and electromigration lifetime. The results indicate that DOM can be successfully integrated with less process steps and better performance.     

Development and validation of a behavioural video coding scheme for detecting mental workload in manual assembly

Abstract

Manual assembly in the future Industry 4.0 workplace will put high demands on operators’ cognitive processing. The development of mental workload (MWL) measures therefore looms large. Physiological gauges such as electroencephalography (EEG) show promising possibilities, but still lack sufficient reliability when applied in the field. This study presents an alternative measure with a substantial ecological validity. First, we developed a behavioural video coding scheme identifying 11 assembly behaviours potentially revealing MWL being too high. Subsequently, we explored its validity by analysing videos of 24 participants performing a high and a low complexity assembly. Results showed that five of the behaviours identified, such as freezing and the amount of part rotations, significantly differed in occurrence and/or duration between the two conditions. The study hereby proposes a novel and naturalistic method that could help practitioners to map and redesign critical assembly phases, and researchers to enrich validation of MWL-measures through measurement triangulation.

Practitioner summary: Current physiological mental workload (MWL) measures still lack sufficient reliability when applied in the field. Therefore, we identified several observable assembly behaviours that could reveal MWL being too high. The results propose a method to map MWL by observing specific assembly behaviours such as freezing and rotating parts.

Abbreviations: MWL: mental workload; EEG: electroencephalography; fNIRS: functional near infrared spectroscopy; AOI: area of interest; SMI: SensoMotoric Instruments, ETG: Eye-Tracking Glasses; FPS: frames per second; BORIS: Behavioral Observation Research Interactive Software; IRR: inter-rater reliability; SWAT: Subjective Workload Assessment Technique; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EL: emotional load; DSSQ: Dundee Stress State Questionnaire; PHL: physical load; SBO: Strategisch Basis Onderzoek     

Selling and installing heat pumps: influencing household practices

When installing energy-efficient technologies in housing, such as heat pumps, the energy savings predicted by technical analyses are often not realized, resulting in a performance gap. This study focuses on air-to-air heat pumps in residential settings. Interviews with actors in Scandinavia who are involved in selling and installing heat pumps are analysed to understand what role these actors have in relation to the performance gap. Previous studies have focused on households and their everyday practices with heat pumps. This study focuses on the process of integrating the heat-pump technologies into homes, and analyses the role of professional practices from supply-side actors (e.g. advice, provision and installation) in relation to questions of residential comfort, know-how and use, as well as the material (physical) integration of heat pumps into homes. In analysing these questions, the study’s contribution is a focus on how to understand material elements within practice–theoretical approaches. From a policy perspective, the analysis shows that a sole focus on the efficiency of technologies is too limited in terms of achieving reduced energy consumption. There is potential for different actors on the provision side to be assigned new roles in order to realize more energy savings.     

The role of risk in e-retailers’ adoption of payment methods: evidence for transition economies

We use logit analysis to exploit a self-collected dataset on the payment and delivery options offered by the vast majority of B2C websites in five Central Asian transition economies. Specifically, we conduct a supply-side test of (elements of) the Transaction Context Model, which highlights the role of perceived risk. Our results confirm that e-retailers in sectors with higher average transaction values are more likely to adopt ‘pay in advance’ instruments—such as debit cards—that have a lower payment risk for the seller. We also find that merchants who offer higher-risk delivery options are more prone to also adopt higher-risk payment instruments (such as credit cards). Our control variables also yield interesting results. In particular, in line with the network externalities theory, we find evidence that the offline penetration of a payment instrument positively affects online merchant adoption.     

On a More Accurate Assessment of Scaled Copper/Low-k Interconnects Performance

Interconnect RC delay, predominantly affected by the effective dielectric constant (k-value) and by the copper resistivity (rho_Cu), is an important performance metric for back-end-of-line (BEOL) process assessment. As process technology scales, interpretation of fundamental process-induced RC delay variations becomes a challenge as the relative importance of statistical process-induced fluctuations (variation of critical dimensions during plasma etching of low-k materials, line profiles, thickness nonuniformity, etc.) grows rapidly and begins to show. A more accurate interpretation of experimental data and prediction of future performance trends requires a more realistic assessment that accounts for such statistical fluctuations. In this paper, an inventory of the most common possible sources of statistical process-induced RC delay variations is made, parameterized, and subsequently used to generate a realistic 2-D interconnect model from which, R and C, and thereby RC delay, are computed. For both wire resistivity and RC, response surface models (RSM) are subsequently generated based on the results of a full factorial design-of-experiment analysis with these input parameters. Finally, based on the RSMs, an improved methodology of interconnect performance evaluation is proposed.     

Micro-dosing as a pathway to Africa’s Green Revolution: evidence from broad-scale on-farm trials

Next to drought, poor soil fertility is the single biggest cause of hunger in Africa. ICRISAT-Zimbabwe has been working for the past 10 years to encourage small-scale farmers to increase inorganic fertiliser use as the first step towards Africa’s own Green Revolution. The program of work is founded on promoting small quantities of inorganic nitrogen (N) fertiliser (micro-dosing) in drought-prone cropping regions. Results from initial on-farm trials showed that smallholder farmers could increase their yields by 30–100% through application of micro doses, as little as 10 kg Nitrogen ha⁻¹. The question remained whether these results could be replicated across much larger numbers of farmers. Wide scale testing of the micro-dosing (17 kg Nitrogen ha⁻¹) concept was initiated in 2003/2004, across multiple locations in southern Zimbabwe through relief and recovery programs. Each year more than 160,000 low resourced households received at least 25 kg of nitrogen fertiliser and a simple flyer in the vernacular explaining how to apply the fertiliser to a cereal crop. This distribution was accompanied by a series of simple paired plot demonstration with or without fertiliser, hosted by farmers selected by the community, where trainings were carried out and detailed labour and crop records were kept. Over a 3 year period more than 2,000 paired-plot trials were established and quality data collected from more than 1,200. In addition, experimentation to derive N response curves of maize (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R.Br.) in these environments under farmer management was conducted. The results consistently showed that micro-dosing (17 kg Nitrogen ha⁻¹) with nitrogen fertiliser can increase grain yields by 30–50% across a broad spectrum of soil, farmer management and seasonal climate conditions. In order for a household to make a profit, farmers needed to obtain between 4 and 7 kg of grain for every kg of N applied depending on season. In fact farmers commonly obtained 15–45 kg of grain per kg of N input. The result provides strong evidence that lack of N, rather than lack of rainfall, is the primary constraint to cereal crop yields and that micro-dosing has the potential for broad-scale impact on improving food security in these drought prone regions.     

Plasma damage in p-GaN

The effect of Inductively Coupled Plasma H₂ or Ar discharges on the breakdown voltage of p-GaN diodes was measured over a range of ion energies and fluxes. The main effect of plasma exposure is a decrease in net acceptor concentration to depths of 400–550 Å. At high ion fluxes or energies there can be type conversion of the initially p-GaN surface. Post etch annealing at 900°C restores the initial conductivity.     

Plasma insulin and growth hormone concentrations in pregnant sheep II: post-absorptive levels in mid- and late pregnancy

1. The incorporation of L-[U-14C]leucine, L[U-14C]histidine and L-[U-14C]phenylalanine into casein secreted during perfusion of isolated guinea-pig mammary glands was demonstrated. 2. The extent of incorporation of label into casein residues was consistent with their being derived from free amino acids of the perfusate plasma. 3. The mean transit time of the amino acids from perfusate into secreted casein was approx. 100 min. 4. Whereas radioactive histidine and phenylalanine were incorporated solely into milk protein, radioactivity from [U-14C]valine was also transferred to CO2 and to an unidentified plasma component, and from [U-14C]leucine to plasma glutamic acid. 5. Evidence from experiments with [U-14C]phenylalanine suggests that, as in rats, but in contrast with ruminant species, guinea-pig mammary tissue does not possess phenyl alanine hydroxylase activity. 6. The results are discussed in relation to the possible role of essential amino acid catabolism in the control of milk-protein synthesis.