Superimposed channel training for two-way MIMO relay systems

Two-way relaying systems are known to be capable of providing higher spectral efficiency compared with one-way relaying systems. However, the channel estimation problem for two-way relaying systems becomes more complicated. In this paper, we propose a superimposed channel training scheme for two-way MIMO relay communication systems, where the individual channel information for users-relay and relay-users links are estimated. The optimal structure of the source and relay training sequences are derived when the mean-squared error (MSE) of channel estimation is minimized. We also optimize the power allocation between the source and relay training sequences to improve the performance of the algorithm. Numerical examples are shown to demonstrate the performance of the proposed channel training algorithm.

On the throughput of two-way relay networks using network coding

 Network coding has shown the promise of significant throughput improvement. In this paper, we study the network throughput using network coding and explore how the maximum throughput can be achieved in a two-way relay wireless network. Unlike previous studies, we consider a more general network with arbitrary structure of overhearing status between receivers and transmitters. To efficiently utilize the coding opportunities, we invent the concept of network coding cliques (NCCs), upon which a formal analysis on the network throughput using network coding is elaborated. In particular, we derive the closed-form expression of the network throughput under certain traffic load in a slotted ALOHA network with basic medium access control. Furthermore, the maximum throughput as well as optimal medium access probability at each node is studied under various network settings. Our theoretical findings have been validated by simulation as well.

Channel estimation for frequency-selective two-way MIMO relay systems

In this paper, we investigate the channel estimation problem for two-way multiple-input multiple-output (MIMO) relay communication systems in frequency-selective fading environments. We propose a superimposed channel training algorithm to estimate the individual channel state information (CSI) of the first-hop and second-hop links for two-way MIMO relay systems with frequency-selective fading channels. In this algorithm, a relay training sequence is superimposed on the received signals at the relay node to assist the estimation of the second-hop channel matrices. The optimal structure of the source and relay training sequences is derived to minimize the meansquared error (MSE) of channel estimation. We also derive the optimal power allocation between the source and relay training sequences. Numerical examples are shown to demonstrate the performance of the proposed algorithm.

Channel estimation for two-way MIMO relay systems in frequency-selective fading environments

© 2002-2012 IEEE. In this paper, we investigate the channel estimation problem for two-way multiple-input multiple-output (MIMO) relay communication systems in frequency-selective fading environments. We apply the method of superimposed channel training to estimate the individual channel state information (CSI) of the first-hop and second-hop links for two-way MIMO relay systems with frequency-selective fading channels. In this algorithm, a relay training sequence is superimposed on the received signals at the relay node to assist the estimation of the second-hop channel matrices. The optimal structure of the source and relay training sequences is derived to minimize the mean-squared error (MSE) of channel estimation. Moreover, the optimal power allocation between the source and relay training sequences is derived to improve the performance of channel estimation. Numerical examples are shown to demonstrate the performance of the proposed superimposed channel training algorithm for two-way MIMO relay systems in frequency-selective fading environments.

Experimental investigation on CFRP-steel bond properties using ionic liquid

Solving the problem of pre mature debonding of CFRP retrofitted structure is a main concern for most of structural engineers nowadays. Reducing the brittleness of the bonding agent at the CFRP/concrete interface is a major factor to avoid this behaviour. In this research, the effect of modifying the bonding agent using different percentages of ionic liquid (IL) is investigated. This paper reports on an experimental investigation on the behaviour of modified epoxy resin with IL. Steel plates were used as hosting surface of the CFRP laminates, the laminates were attached to the steel surface using the IL modified epoxy. The shear mechanism at the interface of CFRP laminates to steel plates is discussed considering the relationship between the shear and the slip at the interface. The shear stress- displacement are traced for all specimens, the results are compared with control test prepared using unmodified epoxy. A 20% IL modified epoxy shows improved Behaviour. The improvement is with respect to ductility enhancement of the overall behaviour.

Coping with economic deprivation during unemployment

The negative impact of unemployment on psychological health is well known. Less is known of the ways that people cope with the problems associated with unemployment, one of which is economic deprivation. This study examined the interrelationships between employment status (200 unemployed participants and 128 employed participants), economic deprivation, coping-efforts and psychological health. It also examined the moderating effect of coping on the relationship between economic deprivation (restriction of spending for material necessities and restriction of spending for meaningful leisure activity) and psychological health. The results suggest that economic deprivation is experienced differentially in terms of material necessities and meaningful leisure activities with unemployed respondents differing from employed on levels of deprivation for meaningful leisure activities but not for material necessities. Employment status, economic deprivation for meaningful leisure activity, solution-oriented coping and affective-based coping significantly predicted depressive affect and self-esteem. Depressive affect was also predicted by economic deprivation for material necessities. A number of significant two-way interactions show that the relationship between economic deprivation and psychological health was conditional upon the use of solution-oriented coping. Results also showed that the relationship between employment status and depressive affect was moderated by the use of affective-based coping. The incorporation of these findings into intervention programmes for unemployed persons is discussed.

Income differences in food consumption in the 1995 Australian national nutrition survey

Objective: To assess the relationships between an index of per capita income and the intake of a variety of individual foods as well as groups of food for men and women in different age groups. Design: Cross-sectional national survey of free-living men and women. Subjects: A sample of 5053 males and 5701 females aged 18 y and over who completed the Australian National Nutrition Survey 1995. Methods: Information about the frequency of consumption of 88 food items was obtained. On the basis of scores on the Food Frequency Questionnaire, regular and irregular consumers of single foods were identified. The relationships between regularity of consumption of individual foods and per capita income were analysed via contingency tables. Food variety scores were derived by assigning individual foods to conventional food group taxonomies, and then summing up the dichotomised intake scores for individual foods within each food group. Two-way ANOVA (income age group) were performed on the food variety scores for males and females, respectively. Results: Per capita income was extensively related to the reported consumption of individual foods and to total and food group variety indices. Generally, both men and women in low income households had less varied diets than those in higher-income households. However, several traditional foods were consumed less often by young high-income respondents, especially young women. Conclusions: Major income differentials in food variety occur in Australia but they are moderated by age and gender. Younger high-income women, in particular, appear to have rejected a number of traditional foods, possibly on the basis of health beliefs. The findings also suggest that data aggregation has marked effects on income and food consumption relationships.

The relationship between education and food consumption in the 1995 Australian national nutrition survey

Objective: To assess the relationship between education and the intake of a variety of individual foods, as well as groups of foods, for Australian men and women in different age groups.

Design: Cross-sectional national survey of free-living men and women. Subjects: A sample of 2501 men and 2739 women aged 18 years and over who completed the National Nutrition Survey (NNS) 1995.

Methods: Information about the frequency of consumption of 88 food items was obtained using a food-frequency questionnaire in a nation-wide nutrition survey. Irregular and regular consumers of foods were identified according to whether they consumed individual foods less than or more than once per month. The relationship between single foods and an index of education (no post-school qualifications, vocational, university) was analysed via contingency table chi-square statistics for men and women. Food group variety scores were derived by assigning individual foods to conventional food group taxonomies, and then summing the dichotomised intake scores for individual foods within each food group. Two-way analyses of variance (education by age groups) were performed on food variety scores for men and women, separately.

Results: While university-educated men and women consumed many individual foods more regularly than less-educated people, they were less likely to be regular consumers of several meat products. The relationship between education and food consumption was less apparent when individual food scores were aggregated into food group scores. University-educated men and women exhibited higher scores on total food group variety than the other educational groups.

Conclusions: Higher education is associated with the regular consumption of a wider variety of foods. Aggregation of individual food consumption indices into food variety scores may mask the apparent effects of educational background on food consumption.

Is a contained fire less risky than a going fire? Career and volunteer firefighters

Since fighting fires can pose a great risk to the lives of firefighters, it is important to understand how they perceive risks in dynamic wildfire situations. The aim of the current study was to determine whether career and volunteer firefighters differ in their perception of the risk of a going vs. contained fire and whether descriptions of a fire as either going or contained affected perceptions of risk. It was expected that career firefighters would rate a contained fire as significantly riskier than would volunteer firefighters. The sample consisted of 55 career and 84 volunteer CFA Victorian firefighters (134 males and 5 females). An ambiguous wildfire scenario was presented and described as either going or contained and risk ratings were recorded. Two-way ANOVA results showed that career firefighters rated a going fire as equally risky as a contained fire. On the other hand, volunteer firefighters perceived a fire described as contained to be significantly less risky than a fire described as going, despite the fact that the same fireground conditions were described in both cases. It was concluded that a framing effect had occurred and that career firefighters demonstrated a higher level of situation awareness than volunteer firefighters due to their heightened levels of risk perception when exposed to contained wildfire scenarios. A practical implication of the current research is that those conducting firefighting briefings need to be aware of possible framing effects in the way information is presented to firefighters and need to ensure that all briefings make risks cognitively salient to firefighters.

Views from the executive suite : lessons from the introduction of performance management

Performance management introduced to the senior health executive levels in the New South Wales public health care system included the senior executive service in 1989 and, as a key element of that service, performance agreements in 1990. This is the first qualitative study examining senior health executives' personal experiences of these changes. In consideration of what has been learnt from the most relevant literature and this study, this paper concludes that the introduction and implementation performance management is a continuous process. This process includes the key steps of planning, measuring, monitoring and evaluating. It can be used as a means to achieve overall effective organisation performance by bringing in a two way management process for the organisation and its senior health executives.

Institutional ownership and firm performance: evidence from Finland

This paper investigates the relationship between different classes of institutional investors and firm performance. Using industry level data from Finland, which is characterized by various institutional investors who own multiple ownership stakes in different firms across a broad spectrum of industries, the paper exhibits two novelties. First, unlike previous studies which treated institutional investors as a monolithic group, we segment them in classes. Second, we recognize the joint determination of firm performance and institutional ownership. We account for this issue in the context of a system of equations, using three stage least squares methodology. The empirical results suggest a significant two-way feedback between firm performance and institutional equity ownership. However, this effect is not symmetric. We find that institutional investors with likely investment and business ties with firms have adverse (negative) effect on firm performance and the impact is very significant in comparison to the negative effect of firm performance on institutional ownership.

Social, cultural and environmental influences on child activity and eating in Australian migrant communities

Aim: This study set out to examine the socio-cultural, familial and environmental factors influencing health, eating habits and patterns of physical activity contributing to child and adolescent overweight and obesity. Methods: Semi-structured, community-based interviews were conducted with contrasting key informant three-generation families; and generation by generation focus groups of grandparents, parents and children from four cultural communities in the state of Victoria, Australia. Purposive sampling occurred from Turkish, Greek, Indian and Chinese communities that have migrated to Australia within the last three generations (n = 160, eight families, 47 children aged 5–15 years, 29 parents, 42 grandparents). Results: Evidence of two-way influences on eating and physical activity across three generations was evident, with children reporting the greatest cross-cultural diversity. A range of dietary restrictions was reported across all cultural groups. Efforts to foster healthy eating and lifestyle patterns within communities were evident. Parents, as a generation in particular, felt the need for more access to education and support regarding healthy limits for pre-puberty and puberty stages. Conclusion: There is a dynamic influence of culture on many aspects of family lifestyle across three generations. To achieve successful intervention design, childhood obesity researchers need to collaborate with diverse groups and communities. Considering the role and influence of extended family, a multigenerational, whole-of-community approach beyond that of parent and child populations ought to be considered.

A practitioner's report on the interactive effects of socio-demographic barriers to travel

Researchers have viewed constraints as a subset of reasons for not engaging in a particular behavior. This study investigates the impact of two-way interactions between age, income, and life stage (forming groups of more and less constrained respondents) on dependent variables comprising intentions held by Australian residents to travel intrastate, interstate or overseas for a vacation. A representative sample of 49,105 Australian respondents is utilized. Binary logistic regression is used to profile respondents who intend to take a domestic or an overseas holiday of more than three days duration. This paper finds that the interactions between the constraint variables of age, income and life stage are important in explaining travel preferences. Constraint groups are then formed by combining the important constraint variables. There are significant levels of vacation travel by even the most constrained groups as well as significant amounts of non-travel by the least constrained sectors of our society. Marketing insights and recommendations are provided for the most constrained travel group and the least constrained travel group.

The mother-daughter guilt dynamic : effects of type 1 diabetes during life transitions

Aim. The aim of the study was to explore and describe the strategies young women with type 1 diabetes used to manage life transitions. The paper describes one aspect of how guilt dynamic often operates between mothers and daughters and how the women managed the guilt dynamic to create stability in their lives.
Background. When a child is diagnosed with diabetes, major transitional changes occur in the relationships between the mother and her child. The changes affect the psychological and social aspects of their lives and have a major impact on how young women manage their diabetes. A guilt dynamic between mothers and young women with diabetes emerged as a major theme in a larger study that investigated how young women with diabetes managed life transitions. Although the literature indicates that mothers of chronically ill children experience guilt feelings towards their children, little research was identified that addressed the emotional dynamics between mothers and daughters with diabetes.
Design. Using grounded theory method, interviews were conducted with 20 women with type 1 diabetes and five mothers during 2002 and 2003. Constant comparative analysis was used to analyse the data and develop an in-depth understanding of the experience of living with diabetes during life transitions.
Findings. The findings revealed that guilt feelings created a two-way dependency between mothers and their daughters with diabetes. The two-way dependency involved feelings of being a burden to each other, difficulty balancing responsibilities for diabetes management, difficulty relinquishing emotional and social dependency especially during life transitions. In addition, these issues were rarely discussed openly with each other or with health professionals. The findings provide additional information about the human experience of the mother–daughter relationship and the effect on coping with diabetes in the context of life transitions.
Conclusions. Understanding the impact diabetes has on the emotional and social well being of both women with type 1 diabetes and their mothers is critical in planning appropriate support for both groups. Most importantly, it is critical to understand the guilt dynamic that operates during young women with diabetes' life transitions when the daughters' dependency on their mother's control and responsibility for diabetes management undergo changes resulting in emotional responses, especially guilt feelings.
Relevance to clinical practice. Health professionals need to understand the emotional and social impact of the guilt dynamics between young women with type 1 diabetes and their mothers. Adequate and appropriate support can minimize the guilt feelings and enhance stability and quality of life for both mothers and their daughters, especially during major life transitions, such as motherhood.