G. Khrenov, V. Ryzhii and S. Kartashov
An efficient numerical model of heterojunction bipolar transistor high frequency performance is proposed. The developed model is based on the ensemble Monte Carlo particle…
Abstract
An efficient numerical model of heterojunction bipolar transistor high frequency performance is proposed. The developed model is based on the ensemble Monte Carlo particle simulator. The validity and accuracy of the model are verified by comparing of the results of the model prediction with the experimental dates. The role of the thickness of the collector junction on the transistor cut‐off frequency is investigated and it is found that transistor cut‐off frequency as a function of the collector thickness has a maximum.
This brief survey notes new publications which contribute to our understanding of the book as it developed in Siberia. Soviet scholars and librarians have a strong tradition of…
Abstract
This brief survey notes new publications which contribute to our understanding of the book as it developed in Siberia. Soviet scholars and librarians have a strong tradition of interest in the study of the book «knigovedenie». The rather numerous works which have appeared recently on the vast Siberian area will be useful in understanding regional printing developments in the Soviet Union.
This review looks firstly at a set of recent articles that examine basic concepts of interlending in particular and resource sharing in general. Some authors are supportive of…
Abstract
This review looks firstly at a set of recent articles that examine basic concepts of interlending in particular and resource sharing in general. Some authors are supportive of resource sharing and interlending, while others question its validity, demanding better examination of its benefits or better local provision. A very forthright paper concentrates on access, whilst another foresees greater user involvement in interlending. New technological developments are reported in a review of several articles on the successes and failures of telefacsimile transmission, ending with a brief mention of a new development — CD—hypenROMs. The European Communities' Docolsys proposal is reported, and a series of contrasting articles on interlending and union catalogues in the USSR is discussed. Recent developments in Canada are briefly reported, and the review ends with a consideration of a paper on humanities interlending requests surveyed by a Spanish research institute.
There are three purposes in this paper: to verify the importance of bi-directional fluid-structure interaction algorithm for centrifugal impeller designs; to study the…
Abstract
Purpose
There are three purposes in this paper: to verify the importance of bi-directional fluid-structure interaction algorithm for centrifugal impeller designs; to study the relationship between the flow inside the impeller and the vibration of the blade; study the influence of material properties on flow field and vibration of centrifugal blades.
Design/methodology/approach
First, a bi-directional fluid-structure coupling finite element numerical model of the supersonic semi-open centrifugal impeller is established based on the Workbench platform. Then, the calculation results of impeller polytropic efficiency and stage total pressure ratio are compared with the experimental results from the available literature. Finally, the flow field and vibrational characteristics of 17-4PH (PHB), aluminum alloy (AAL) and carbon fiber-reinforced plastic (CFP) blades are compared under different operating conditions.
Findings
The results show that the flow fields performance and blade vibration influence each other. The flow fields performance and vibration resistance of CFP blades are higher than those of 17-4PH (PHB) and aluminum alloy (AAL) blades. At the design speed, compared with the PHB blades and AAL blades, the CFP blades deformation is reduced by 34.5% and 9%, the stress is reduced by 69.6% and 20% and the impeller pressure ratio is increased by 0.8% and 0.14%, respectively.
Originality/value
The importance of fluid-structure interaction to the aerodynamic and structural design of centrifugal impeller is revealed, and the superiority over composite materials in the application of centrifugal impeller is verified.
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The article analyzes the development of the Finnish research in library and information science into its present position of high qualitative and quantitative level (in relation…
Abstract
The article analyzes the development of the Finnish research in library and information science into its present position of high qualitative and quantitative level (in relation to the size of the research community). A number of aspects that may explain the success of the Finnish research are presented: 1) the early academic context, i.e., the establishment of the chair in LIS at the University of Tampere in 1971, 2) the new conception of LIS that emerged in Finland in the early 1980s shifting the attention from institutions into users and actions, 3) internationalization of research including publishing in peer reviewed journals, participating in international conferences, inviting foreign top-researchers into Finland, and organizing international conferences that have become institutionalized (CoLIS and ISIC), and 4) the selection of priority areas for the research effort combined with the concentration of research and doctoral education in research groups.
Mike Cornford, Ruth Kerns, Terry Hanstock, Allan Bunch and Edwin Fleming
… Strange but true facts, number 7: Wandsworth is famous for more than its blue halo.
Liudmila Tarabashkina, Pascale G. Quester and Roberta Crouch
Studies to date have focused on one or very few factors, rather than exploring a host of influences associated with children’s consumption of energy-dense foods. This is…
Abstract
Purpose
Studies to date have focused on one or very few factors, rather than exploring a host of influences associated with children’s consumption of energy-dense foods. This is surprising as multiple agents are relevant to children’s food consumer socialisation (parents, peers, social norms and food advertising). This study aims to address these gaps and offers the first comprehensive empirical assessment of a wide cluster of variables.
Design/methodology/approach
A cross-sectional study was undertaken with children aged 7-13 years and their parents/main carers, collecting family metrics from parents and data directly from children. Structural Equation Modelling was used to estimate a series of interdependence relationships in four steps, revealing the increased explained variance in children’s consumption of energy-dense foods.
Findings
The inclusion of multiple potential factors increased the percentage of explained variance in children’s consumption of energy-dense foods. The models explicate which factors relate to frequent consumption in children, and clarify various indirect influences on children through parents.
Originality/value
For the first time, a wider range of variables was integrated to maximise the percentage of explained variance in children’s behaviour, providing policy makers and social marketers with novel insights regarding areas that need to be prioritised for consumer education. Both direct and indirect relationships were assessed. Data were collected from parents and their children to provide an original methodological contribution and richer data for investigation.
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Canicio Dzingirai and Nixon S. Chekenya
The life insurance industry has been exposed to high levels of longevity risk born from the mismatch between realized mortality trends and anticipated forecast. Annuity providers…
Abstract
Purpose
The life insurance industry has been exposed to high levels of longevity risk born from the mismatch between realized mortality trends and anticipated forecast. Annuity providers are exposed to extended periods of annuity payments. There are no immediate instruments in the market to counter the risk directly. This paper aims to develop appropriate instruments for hedging longevity risk and providing an insight on how existing products can be tailor-made to effectively immunize portfolios consisting of life insurance using a cointegration vector error correction model with regime-switching (RS-VECM), which enables both short-term fluctuations, through the autoregressive structure [AR(1)] and long-run equilibria using a cointegration relationship. The authors also develop synthetic products that can be used to effectively hedge longevity risk faced by life insurance and annuity providers who actively hold portfolios of life insurance products. Models are derived using South African data. The authors also derive closed-form expressions for hedge ratios associated with synthetic products written on life insurance contracts as this will provide a natural way of immunizing the associated portfolios. The authors further show how to address the current liquidity challenges in the longevity market by devising longevity swaps and develop pricing and hedging algorithms for longevity-linked securities. The use of a cointergrating relationship improves the model fitting process, as all the VECMs and RS-VECMs yield greater criteria values than their vector autoregressive model (VAR) and regime-switching vector autoregressive model (RS-VAR) counterpart’s, even though there are accruing parameters involved.
Design/methodology/approach
The market model adopted from Ngai and Sherris (2011) is a cointegration RS-VECM for this enables both short-term fluctuations, through the AR(1) and long-run equilibria using a cointegration relationship (Johansen, 1988, 1995a, 1995b), with a heteroskedasticity through the use of regime-switching. The RS-VECM is seen to have the best fit for Australian data under various model selection criteria by Sherris and Zhang (2009). Harris (1997) (Sajjad et al., 2008) also fits a regime-switching VAR model using Australian (UK and US) data to four key macroeconomic variables (market stock indices), showing that regime-switching is a significant improvement over autoregressive conditional heteroscedasticity (ARCH) and generalised autoregressive conditional heteroscedasticity (GARCH) processes in the account for volatility, evidence similar to that of Sherris and Zhang (2009) in the case of Exponential Regressive Conditional Heteroscedasticity (ERCH). Ngai and Sherris (2011) and Sherris and Zhang (2009) also fit a VAR model to Australian data with simultaneous regime-switching across many economic and financial series.
Findings
The authors develop a longevity swap using nighttime data instead of usual income measures as it yields statistically accurate results. The authors also develop longevity derivatives and annuities including variable annuities with guaranteed lifetime withdrawal benefit (GLWB) and inflation-indexed annuities. Improved market and mortality models are developed and estimated using South African data to model the underlying risks. Macroeconomic variables dependence is modeled using a cointegrating VECM as used in Ngai and Sherris (2011), which enables both short-run dependence and long-run equilibrium. Longevity swaps provide protection against longevity risk and benefit the most from hedging longevity risk. Longevity bonds are also effective as a hedging instrument in life annuities. The cost of hedging, as reflected in the price of longevity risk, has a statistically significant effect on the effectiveness of hedging options.
Research limitations/implications
This study relied on secondary data partly reported by independent institutions and the government, which may be biased because of smoothening, interpolation or extrapolation processes.
Practical implications
An examination of South Africa’s mortality based on industry experience in comparison to population mortality would demand confirmation of the analysis in this paper based on Belgian data as well as other less developed economies. This study shows that to provide inflation-indexed life annuities, there is a need for an active market for hedging inflation in South Africa. This would demand the South African Government through the help of Actuarial Society of South Africa (ASSA) to issue inflation-indexed securities which will help annuities and insurance providers immunize their portfolios from longevity risk.
Social implications
In South Africa, there is an infant market for inflation hedging and no market for longevity swaps. The effect of not being able to hedge inflation is guaranteed, and longevity swaps in annuity products is revealed to be useful and significant, particularly using developing or emerging economies as a laboratory. This study has shown that government issuance or allowing issuance, of longevity swaps, can enable insurers to manage longevity risk. If the South African Government, through ASSA, is to develop a projected mortality reference index for South Africa, this would allow the development of mortality-linked securities and longevity swaps which ultimately maximize the social welfare of life assurance policy holders.
Originality/value
The paper proposes longevity swaps and static hedging because they are simple, less costly and practical with feasible applications to the South African market, an economy of over 50 million people. As the market for MLS develops further, dynamic hedging should become possible.
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Ming Yuan, James Lawrence Seale Jr, Thomas Wahl and Junfei Bai
The purpose of this paper is to offer an overview of dietary transition patterns and a discussion of the food-related health issues in China.
Abstract
Purpose
The purpose of this paper is to offer an overview of dietary transition patterns and a discussion of the food-related health issues in China.
Design/methodology/approach
The paper builds on a review of the existing literature on food consumption and diet changes in China, and highlights with specific attention to increasing food consumed away from home, the rising demand for fast and processed foods, and the popularizing of western-style foods in Chinese diets.
Findings
China’s food consumption patterns rapidly transitioned from one in which grains and vegetables dominated to one having more animal products and more diversification. More foods are consumed away from home and in the form of fast and processed. Income growth played and will continue to play a critical role in shifting the structure of food consumption. On the other hand, China is on a fast track from a lean population to one in which being overweight or obese. The associations between health outputs and food transitions, however, are inconclusive.
Originality/value
The main findings of this study have implications for better understanding the key trends and driving forces of China’s food demand system. Moreover, the results from this review are essential for food-related policymaking in many emerging economies where coexistence of undernutrition, deficiency of micronutrients and overweight and obesity is a common challenge to the society and individual households.