The end of cheap oil: Current status and prospects

This paper, analyses the factors impacting the price of crude oil in order to examine the likely evolution of the oil market and attempts to answer the question, whether cheap oil is already a thing of the past. Based on data made publicly available mostly by the major oil companies, it examines the effects of demand and supply, the evolution of world oil reserves, the trends in new discoveries of new oilfields, the evolution of world Gross Domestic Product (GDP), and the depletion of oil resources. The analysis concludes that the world peak in conventional oil production—the point beyond which oil production will irreversibly start declining—is approaching and will be reached, even according to the most optimistic scenarios, before 2040 and quite possibly much sooner. If the appropriate solutions for substituting crude oil and for conserving the use of energy are not implemented in time, then the current upward trend in oil prices is bound to continue.     

A multi-level model on automated vehicle acceptance (MAVA): a review-based study

Abstract

Automated vehicle acceptance (AVA) is a necessary condition for the realisation of higher-level objectives such as improvements in road safety, reductions in traffic congestion and environmental pollution. On the basis of a systematic literature review of 124 empirical studies, the present study proposes MAVA, a multi-level model to predict AVA. It incorporates a process-oriented view on AVA, considering acceptance as the result of a four-stage decision-making process that ranges from the exposure of the individual to automated vehicles (AVs) in Stage 1, the formation of favourable or unfavourable attitudes towards AVs in Stage 2, making the decision to adopt or reject AVs in Stage 3, to the implementation of AVs into practice in Stage 4. MAVA incorporates 28 acceptance factors that represent seven main acceptance classes. The acceptance factors are located at two levels, i.e., micro and meso. Factors at the micro-level constitute individual difference factors (i.e., socio-demographics, personality and travel behaviour). The meso-level captures the exposure of individuals to AVs, instrumental domain-specific, symbolic-affective and moral-normative factors of AVA. The literature review revealed that 6% of the studies investigated the exposure of individuals to AVs (i.e., knowledge and experience). 22% of the studies investigated domain-specific factors (i.e., performance and effort ­expectancy, safety, facilitating conditions, and service and vehicle ­characteristics), 4% symbolic-affective factors (i.e., hedonic motivation and social influence), and 12% moral-normative factors (i.e., perceived benefits and risks). Factors related to a person’s socio-demographic profile, travel behaviour and personality were investigated by 28%, 15% and 14% of the studies, respectively. We recommend that future studies empirically verify MAVA using longitudinal or experimental studies.     

Case-based retrieval of 3-dimensional shapes for the design of metal castings

This paper describes research into retrieval based on 3-dimensional shapes for use in the metal casting industry. The purpose of the system is to advise a casting engineer on the design aspects of a new casting by reference to similar castings which have been prototyped and tested in the past. The key aspects of the system are the orientation of the shape within the mould, the positions of feeders and chills, and particular advice concerning special problems and solutions, and possible redesign. The main focus of this research is the effectiveness of similarity measures based on 3-dimensional shapes. The approach adopted here is to construct similarity measures based on a graphical representation deriving from a shape decomposition used extensively by experienced casting design engineers. The paper explains the graphical representation and discusses similarity measures based on it. Performance measures for the CBR system are given, and the results for trials of the system are presented. The competence of the current case-base is discussed, with reference to a representation of cases as points in an n-dimensional feature space, and its principal components visualization. A refinement of the case base is performed as a result of the competence analysis and the performance of the case-base before and after refinement is compared.     

Evaluating the research performance of the Greek medical schools using bibliometrics

Quality in Higher Education Institutions is the subject of several debates in the academic community in a worldwide basis and various efforts are made towards identifying ways to quantify it. In this respect, the use of bibliometrics gains significant ground as an effective tool for the evaluation of universities’ research output. In the present study, the research performance of the seven Greek medical schools is assessed by means of widely accepted and advanced bibliometric indices, such as total and average publications and citations, average and median h- and g-index with and without self-citations for all the 1,803 academics, while statistical analysis of the data was also performed in order to compare the observed differences in the mean values of the calculated indices. Considerable effort was exerted to overcome all inherent limitations of a bibliometric analysis through a meticulous data collection. This large-scale work was conducted both in school and academic rank level leading to interesting results concerning the scientific activity of the medical schools studied as units and of the various academic ranks separately, which can be partially justified with geographic and socioeconomic criteria. In general, bibliometrics demonstrate statistically significant difference in favour of Crete University medical school, while it was also found that self-citations have only marginal effect on the individual’s research profile and the average indices. Finally, the useful findings of the present study render the methodology adopted of high viability for assessing the research performance of Higher Education Institutions even in a broader context.     

Comparison of standard forearm prosthetic loop grafts to composite semiloop forearm grafts (“semi‐grafts”) in hemodialysis patients: A prospective study

Introduction: To prospectively assess the performance of composite semiloop antebrachial grafts (“semi‐grafts,” SGs) in hemodialysis patients. Methods: Eighty‐five patients who received 67 loop antebrachial grafts (LG‐group) and 25 antebrachial semigrafts (SG‐group) were enrolled. SGs were defined as those originating from the brachial artery and anastomosed with the proximal mature mid‐antebrachial cephalic vein. Cephalic vein length should be at least 10 cm in length and of ≥5 mm in diameter for inclusion in the SG‐group. LG‐group included all possible outflow vein options of minimum diameter 3 mm. Kaplan‐Meier statistics was used for comparison of groups. Findings: Main indication for a SG was a failing radiocephalic fistula with extensive distal cephalic vein stenosis not amenable to correction or failed after endovascular repair or requiring long interposition grafting. The mean follow‐up period was 20.16 ± 22.6 and 29.6 ± 36.7 months for the LG‐ and SG‐group, respectively (P = 0.14). Forty‐two patients died during the follow‐up. Primary patency (up to first intervention or failure) at 6 and 12 months for LG‐ vs. SG‐group was 93.9% vs. 83.7% and 47% vs. 55.8% (P = 0.08). Secondary patency (up to abandonment) was 58.2% vs. 61.1% and 36% vs. 45.8% at 12 and 24 months (P = 0.18). Mortality at 48 months was 22.4% (LG‐group) and 24% (SG‐group) (P = 0.9). Discussion: There was a trend toward better primary and secondary patency rates for the SGs especially in the long‐term. This is a valuable option in selected patients that access surgeons and nephrologists should be aware of.     

Robot control system using “intelligent” integrators

Integral control is important in practice, but in many applications for robot systems this control is unsatisfactory, due to large initial conditions or disturbances. The overshoot becomes large, the speed of response not fast enough, and path tracking is needed. One cure for this problem is the use of the intelligent integral controller, which is very simple in implementation. This control scheme, as part of a PID controller, is applied to a robot system and its superiority, from the conventional one, becomes clear. The main advantage of this controller is that it gives very satisfactory results, while being rather simple.     

Non-parametric-validated computer-simulation surrogates: a Pareto formulation

In the surrogate approach to simulation-based optimization, the large-scale simulation is evoked only to construct and validate a simplified input–output model; this simplified input–output model then serves as a simulation surrogate in subsequent engineering optimization studies. We present here ‘basic’ and Pareto surrogate formulations through an illustrative application from fluid dynamics. The critical ingredient of both formulations is a non-parametric statistical validation and error estimation procedure which, based on verifiable hypotheses, precisely quantifies the effect of surrogate-for-simulation substitution on system predictability, stability, and optimality. The Pareto formulation improves upon the basic approach by operating only in the vicinity of the efficient frontier of the output achievable set 𝒜 for problems with many inputs and few outputs, this considerably reduces the dimensionality of the problem, and correspondingly improves the surrogate error estimates. © 1998 John Wiley & Sons, Ltd.     

Packet Routing in Fixed-Connection Networks: A Survey

We survey routing problems on fixed-connection networks. We consider many aspects of the routing problem and provide known theoretical results for various communication models. We focus on (partial) permutation, k-relation routing, routing to random destinations, dynamic routing, isotonic routing, fault tolerant routing, and related sorting results. We also provide a list of unsolved problems and numerous references.