Cross-Spectral Analysis of Midfrequency Acoustic Waves Reflected by the Seafloor

Direct path measurements of a single-bottom interacting path on a vertical array are used to probe the seabed structure. The phase of the cross-spectrum, commonly used in engineering acoustics, permits examination of the importance of subbottom paths. When the cross-spectral phase is linear with frequency it implies that source to receiver propagation is dominated by a single path. A linear cross-spectral phase would also satisfy the linear seabed reflection coefficient phase approximation sometimes employed in forward modeling and geoacoustic inversion approaches. Shallow water measurements of the cross-spectrum, however, evidence a strongly nonlinear phase, below about 1500 Hz at one site, and 600 Hz at another site, implying that: 1) the subbottom structure plays an important role (i.e., a seabed half-space approximation would be inappropriate); and 2) the linear reflection phase approximation would be violated at those frequencie

Experimental High Velocity Acid Jetting in Limestone Carbonates

Acid jetting is a well stimulation technique that is used in carbonate reservoirs. It typically involves injecting acid down hole at high flow rates through small orifices which cause high velocities of acid to strike the borehole wall. The combination of high kinetic energy and chemical reaction of the acid removes drilling mud filter cake from the borehole wall and produces long conductive channels, called wormholes, into the formation, therefore improving well performance. Studies have shown that injecting fluid down hole at high velocities can mitigate damage to wellbore caused by drilling mud filter cake. Both water and acid have shown positive results in such cases. However, there are no laboratory results on how high velocity acid impacts the borehole wall and the formation of wormholes. The purpose of this study is to investigate how the high velocity acid affects the acidizing treatments. The experiments are conducted on 4” diameter by 16” length Indiana limestone cores with acid injected at the velocity of 106 ft/s, 150 ft/s, and 200 ft/s. The experiments are conducted with a constant pressure differential across the core. 15%wt Hydrochloric acid is injected at room temperature at various flux rates. The results show that the higher the velocity of jetted acid, the further it penetrates into the formation. The 200 ft/s acid penetrates furthest into the core, thus potentially lowering the skin factor the greatest. A large cavity is formed into the core from the high velocity acid. This large cavity creates a pathway for acid to divert into the core to create wormholes. Acid jetting cannot be directly compared with matrix acidizing because of the formation of these large cavities. The Buijse-Glasbergen model that is used to predict the formation of wormholes does not accurately match the acid jetting data due to the formation of these large cavities, so the optimum flux and pore volume to breakthrough cannot be accurately determined

Artificial Intelligence (AI) and Digital Transformation in the Insurance Market: A Case Study Analysis of BGL Group

Artificial Intelligence (AI) is transforming the insurance industry and there are many examples in the business press and at industry conferences. However, there is a paucity of detailed conceptual analysis and evaluation of AI technology that places AI in a strategic context and considers how different AI applications fit together and form a coherent picture. In this paper, a detailed case study of BGL group, a leading European insurance firm, is presented. A general business process model of insurance companies is used to structure the analysis. Five AI applications are described using an insurance firm-customer data flow diagram, which illustrates the marketing impact of AI technology and shows the nature of the business value creation process. The results are generalized into an AI customer lifecycle model, which has broad applicability to digital transformation projects. The likely future direction of AI in insurance is outlined and further research opportunities are identified

Light Induced a.c. Loss in Amorphous Semiconductors

Enhanced a.c. losses have been observed in thin films of a-Ge and a-Si exposed to low intensity light, of wavelength 633nm, derived from a He-Ne laser. The samples were prepared in sandwich configuration by R. F. sputtering in argon or argon-hydrogen atmospheres. Illumination intensities of 1uWcm-z or less were applied through a semi-transparent gold top electrode. Changes in a.c. conductivity and capacitance of up to 10% were measured at helium temperatures. The optical response at helium temperatures is non-linear. At high intensities, the permittivity increases as I1/4, but at low intensities the response is closer to The temperature dependence of the response is small up to 20K. The recovery to the dark state is non-exponential and usually many hours elapse before no further change can be detected. When 500nm and 800nm light is used, no difference in response can be seen after the different absorption factors of the semiconductor film at these wavelengths have been accounted for. The loss changes induced in the I 1/4 region are similar in pure a-Si and pure a-Ge films but decrease as the hydrogen content of films increases. At low intensities heavily hydrogenated material shows a greater response than pure material. The following model is used to explain the data. Incident photons generate free carriers which are rapidly trapped by deep, clustered defects. The trapped electrons (or holes) are able to respond to the applied a.c. field and contribute an additional loss. The only escape for the trapped electrons at low temperatures is by tunnelling to a neighbouring excess hole. An simple analysis of the appropriate rate equations leads to carrier densities which compare well to the e. s. r. signal in sputtered material. The above model predicts the I 1/2 behaviour at low intensities. During the decay to dark equilibrium, the induced loss is proportional to -log(time). To account for the form of the decay the model is modified to include the fact that, in the dark, the average excited pair separation will increase with time. By postulating a minimum pair separation it is possible to explain the inconsistency of the slow decays to equilibrium and the recombination times estimated from the high temperature loss. However this model fails in that the predicted maximum pair separation is less than the minimum pair separation. This can only be explained by strong carrier self-trapping at the defect site. The reduced response at higher intensities is ascribed to reduced self-trapping for states excited far from the fermi level. The increased self-trapping in hydrogenated material is also reflected in a slower free decay to equilibrium. The active defect is estimated to be approximately 10A in extent which is consistent with the results of the low temperature a.c. field effect. It is suggested that the optically induced loss is derived from a population of correlated pairs of dangling bond states which exist on the internal surfaces of voids

Internet and Social Media Strategy in Sports Marketing

The Internet and social media are transforming sports marketing. Historically television broadcasting was the main source of revenue for elite sports teams, leagues and sports federations. This is now changing because the Internet creates new possibilities for the distribution and consumption of sporting events. Social media is creating new forms of communication between fans, athletes, teams and sponsors. Mobile technology is also changing the way that fans consume sports content generally and also at live events. These changes create many strategic challenges and opportunities. This case study presents several frameworks and ideas, in particular the sports ecosystem model, event-driven marketing, star marketing and international differences in sports viewing for specific sports. These concepts are illustrated using sports marketing data from ComScore, individual sports organisations and personal research. A framework for the development of a social media strategy is proposed that can be used to evaluate the current position of a sports organisation and also to facilitate the development of a social media strategy. A series of questions is posed to structure the discussion of the strategic and technology issues facing the commercial director of a major sports team. \ \ Keywords: Sports marketing, social media, Internet strategy

International Examples of Large-Scale Systems - Theory and Practice III: Competition and Strategy in Electronic Marketplaces

Electronic marketplaces are evolving in both business to business, and business to consumer contexts. Although the initial hype surrounding all types of marketplaces appears to overstate their short-term impact, established companies across all types of industrial sectors are entering into collaborative, industry-wide initiatives to agree on common technical and trading standards to improve the effectiveness of the interactions between buyers and sellers on a global scale. An overview of contemporary developments is presented, and common patterns across different sectors are identified. Three case studies are presented in the areas of automotive, banking, and consumer markets. It is shown that product-market characteristics affect the formation of business relationships and market structures, and the design of information flows and shared systems is a reflection of typically strong business relationships and hierarchical market structures

The IS Core - X: Information Systems Research and Practice: IT Artifact or a Multidisciplinary Subject?

Much recent debate focuses on the nature of information systems as an academic endeavour and whether it constitutes a single, coherent subject discipline in its own right. This paper comments particularly on the recent paper by Benbasat and Zmud [2003] that proposes an IT artifact model to provide an integrative theme for IS research, and the response by Alter [2003] who presents an alternative paradigm that emphasizes the importance of systems. The approach taken here is to define the terminology of IS and put it into a management context which is implicit in most IS research but is often overlooked in the debates on the nature of academic IS research. It is proposed that a multidisciplinary approach to IS research is the most appropriate way of conceptualizing IS problems, academic research, and business practice, and that the integrating themes arise from the terms \u27information\u27 and \u27systems\u27 rather than from the technology. A multidisciplinary view of IS has different implications for identifying appropriate research problems, research design, publication and dissemination, and for the development of professional bodies than the IT artifact philosophy. It has some similarities to the systems model proposed by Alter and takes this concept further to stress that the IS research field can make a claim not only to systems but to much broader core disciplines in management because of the ubiquitous nature of not only IT, but also because of the central role that information plays in the co-ordination of economic activity in business enterprises. To support the argument, examples of historical IS research are outlined and the importance of earlier multidisciplinary research areas is described, particularly the antecedents of OR research practice in the UK. Finally some tentative ideas on future IS research and practice are outlined