Heterogeneous and homogeneous effects in the thermal cracking of hydrocarbons

Imperial Users onl

Requirements analysis for decision-support system design: evidence from the automotive industry

The purpose of this paper is to outline the requirements analysis that was carried out to support the development of a system that allows engineers to view real-time data integrated from multiple silos such as Product Lifecycle Management (PLM) and Warranty systems, in a single and visual environment. The outcome of this study provides a clear understanding of how engineers working in different phases of the product-lifecycle could utilise such information to improve the decision making process and as a result design better products. This study uses data collected via in-depth semi-structured interviews and workshops that includes people working in various roles within the automotive sector. In order to demonstrate the applicability this approach, SysML diagrams are also provided

Discrete event simulation and virtual reality use in industry: new opportunities and future trends

This paper reviews the area of combined discrete event simulation (DES) and virtual reality (VR) use within industry. While establishing a state of the art for progress in this area, this paper makes the case for VR DES as the vehicle of choice for complex data analysis through interactive simulation models, highlighting both its advantages and current limitations. This paper reviews active research topics such as VR and DES real-time integration, communication protocols, system design considerations, model validation, and applications of VR and DES. While summarizing future research directions for this technology combination, the case is made for smart factory adoption of VR DES as a new platform for scenario testing and decision making. It is put that in order for VR DES to fully meet the visualization requirements of both Industry 4.0 and Industrial Internet visions of digital manufacturing, further research is required in the areas of lower latency image processing, DES delivery as a service, gesture recognition for VR DES interaction, and linkage of DES to real-time data streams and Big Data sets

A Novel Mathematical Model of the Trojan Y-Chromosome Strategy with Optimal Control

Invasive species are a prevalent problem all over the world. Controlling and eradicating an invasive species is an even more diffcult problem. The Trojan Y Chromosome (TYC) eradication strategy is one control method. This method alters the female to male sex ratio by introducing sex reversed males called supermales. These sex reversed males can only produce male progeny. Mathematical models of this strategy have shown that a population can be driven to extinction with a continuous supply of these sex reversed males. There are many different mathematical models of this strategy, but most have serious flaws, such as negative solutions or finite time blow up. In this paper, a new model for the TYC strategy is introduced and an optimal control is established for the introduction rate of the supermales for this new model

Cerebral Oximetry Readings in the Sitting Position Versus Supine Position for Patients Undergoing General Anesthesia

Problem: Inadequate cerebral blood flow is a significant risk for patients undergoing surgery in the sitting position. Placing the patient in a sitting position may cause a drop in pressure at the level of the brain when compounded with induction and maintenance of general anesthesia. These changes may cause a decrease in cerebral blood flow and oxygenation. Inadequate perfusion for a prolonged period of time could produce negative neurological consequences in the short and long term postoperative period. Purpose: The purpose of this project is to determine if there is a significant drop in cerebral oximetry, from baseline, when patients are placed in the sitting position for surgery, while under general anesthesia. Methodology: Data were collected on 50 patients who underwent surgery in the sitting position. The following information was gathered retrospectively for each subject studied: Left and right hemisphere cerebral oximetry readings, age, gender, ASA score, temperature, end-tidal carbon dioxide (ETCO2), blood pressure, and fraction of inspired oxygen (FiO2). A repeated measures analysis of variance (ANOVA) was used for statistical analysis. Results: A decrease in LCOR readings was noted between initial (M=71.46, SD=5.97) and 15 minute post sitting position (M=68.96, SD=6.55), a statistically significant mean decrease of 2.5, 95% CI [0.95, 4.05], p=0.001. There was also a decrease in LCOR readings between initial (M=71.46, SD=5.97) and 30 minute post sitting position (M=68.86, SD=6.85), a statistically significant mean decrease of 2.6, 95% CI [0.84, 4.36], p=0.002. A decrease in RCOR readings was noted between initial (M=71.92, SD=5.88) and 15 minute post sitting position (M=69.12, SD=6.83), a statistically significant mean decrease of 2.8, 95% CI [1.01, 4.59], p=0.001. There was also a decrease in RCOR readings between initial (M=71.92, SD=5.88) and 30 minute post sitting position (M=68.36, SD=7.54), a statistically significant mean decrease of 2.56, 95% CI [0.37, 4.75], p=0.017. Conclusion: Statistically significant differences were determined between initial cerebral oximetry readings and 15 minute post sitting position readings, as well as between initial readings and 30 minute post sitting position readings. This difference was noted for both left and right hemispheres

An Application of Differential Mathematical Modeling Techniques to Study the Ongoing Rabies Epizootic in China

Rabies remains a global public health issue with a wide variety of neurological symptoms such as confusion, slight paralysis, hypersalivation, and hydrophobia. Rabies is usually fatal once symptoms appear. Many species are reservoirs for rabies, such as foxes, racoons, and wild dogs, which in turn can transmit the disease to humans, leading to complex transmission chains. There is a long latent period of rabies, between 1 to 3 months after infection, which further complicates control efforts. Mathematical modeling is a valuable tool in the study of infectious disease outbreaks and there have been many models applied to rabies outbreaks. However, these focus on localized outbreaks that usually involve a single lineage and there have been fewer studies that attempt to model a rabies outbreak at the national level. In this work, we will investigate the surveillance data collected by the Chinese Center for Disease Control for the current Rabies epizootic in China that involves a displacement of one rabies lineage with another. This paper will investigate the suitability of different models for capturing the observed case data at the provincial level

Controlling Auditor Interactions to Improve the Quality of a Financial Statement Audit

Poor quality financial statement audits have a negative impact on the information provided to principals and stakeholders that can increase the risk of corporate fraud. The well-documented collapses of companies, such as Enron and WorldCom, brought the issue of audit quality to the headlines. Using agency theory as the conceptual framework, the purpose of this single case study was to determine what strategies client managers and boards can use to facilitate an engagement with an audit firm and effectively carry out their responsibility to provide effective relevant evidence and support for their management assertions as outlined in the engagement letter. The population comprised a census sample of 9 individuals with direct involvement in the audit process within a Connecticut-based organization and its audit firm. Data collection comprised of semistructured interviews and analysis of public and internal documents. Using methodological triangulation, 5 primary themes emerged including communication, documentation, knowledge and experience, character, and procedural. The findings of this study may promote social change by enhancing knowledge of what role management can play in ensuring a high-quality audit. Improved insight to the audit process may promote investor confidence in the financial statements and economic growth through capital spending

Industrial Relations in Sweden and New Zealand: A Comparison

This paper provides a brief comparison between the Employment Contracts Act 1991 (ECA) and the Swedish equivalent, the Co-Determination Act. The Co-Determination Act is then used to provide a framework against which an alternative to the ECA is discussed. The paper concludes by arguing for a system of contracting which emphasises collective bargaining, noting a number of impediments to its effective operation in New Zealand- at least in the short-term. Two such impediments which are discussed are the current low level of union density and voluntary unionism. Additionally, if New Zealand is to ratify ILO conventions 87 and 98, collective good faith bargaining will have to be embodied in any new legislative framework. Recommendations for such a framework are made herein

A review of key planning and scheduling in the rail industry in Europe and UK

Planning and scheduling activities within the rail industry have benefited from developments in computer-based simulation and modelling techniques over the last 25 years. Increasingly, the use of computational intelligence in such tasks is featuring more heavily in research publications. This paper examines a number of common rail-based planning and scheduling activities and how they benefit from five broad technology approaches. Summary tables of papers are provided relating to rail planning and scheduling activities and to the use of expert and decision systems in the rail industry.EPSR