Effect of body-borne equipment on injury of military pilots and aircrew during a simulated helicopter crash

Military helicopter pilots are expected to wear a variety of items of body-borne equipment during flight so as to be prepared for any situation that may arise in combat. Helicopter seats are designed to a specified weight range for an occupant with equipment. This paper investigates how distributing the equipment on the body affects injury potential during a helicopter crash. A finite element model representing a helicopter seat with a fully deformable 50th percentile Hybrid III carrying equipment was developed. The model was subjected to a standard military certification crash test. Various equipment configurations were investigated and analysed to determine its influence on the risk of injury. It was found that placing the equipment low on the torso, i.e. near the thighs, not only reduces the likelihood of injury in the lumbar, spinal region but also provides favourable results in neck and head injury risk when compared to other configurations investigated. In contrast, placing equipment high on the torso, i.e. close to the chin, increases the lumbar load and implicitly, the risk of head injury. A statistical analysis is carried out using the Wilcoxon Signed Rank Test to deliver probability of loads experienced within a certain interval. This study recommends an equipment configuration that improves survivability for an occupant seated on a fixed load energy absorbing seat which is subjected to Military Standard 58095A Test 4.     

The effects of product involvement and impulse buying on purchase intentions in mobile text advertising

While research in mobile advertising is abundant, limited attention has been paid to date to how consumers respond to mobile advertisements for different product categories and in which way impulsivity affects intentions to purchase. In this paper, we study the dimensionality of the product involvement construct and its effects on consumers’ purchase intentions via a simulated field experiment (N = 736). We show that the cognitive dimension of product involvement and impulsiveness significantly affect purchase intentions. We also present that the relationship between product involvement and purchase intention is moderated by the consumers’ impulse buying personality traits. These findings progress the current state-of-the-art in mobile advertising research, while also having significant practical consequences for the design of effective mobile SMS advertising campaigns.     

Social capital and individual motivations on knowledge sharing: Participant involvement as a moderator

The Internet is a communication channel that allows individuals to share information and knowledge. However, it is not obvious why individuals share knowledge with strangers for no apparent benefit. What are the critical factors influencing such behavior? To attempt to understand this paradox, we combined the theories of social capital and individual motivation to investigate the factors influencing knowledge sharing behavior in a virtual community, applying a participant involvement concept to analyze the moderating effects of individual motivation on knowledge sharing behavior. By analyzing the results of a survey using a questionnaire, we found that altruism, identification, reciprocity, and shared language had a significant and positive effect on knowledge sharing. Reputation, social interaction, and trust had positive effects on the quality, but not the quantity, of shared knowledge. Participant involvement had a moderating effect on the relationship of altruism and the quantity of shared knowledge. Theoretical and managerial implications are discussed.     

Effects of pre-strain and bake-hardening on the crash properties of a top-hat section

The effects of pre-strain on the crushing properties of a crash-box structure are reported for two Advanced High Strength Steels produced by ArcelorMittal (Dual-Phase DP600 and Transformation Induced by Plasticity TRIP780 steels). In addition, the effect of a bake-hardening treatment is studied on the TRIP780 steel. The material's behaviors have been determined in tensile loading in a wide range of strain-rates () including strain-rate jump tests from quasi-static to dynamic loading. These interrupted tests allow us to characterize the effect of the (quasi-static) forming process on the subsequent dynamic behavior associated to the crash event. A phenomenological visco-plastic model, based on the evolution of an internal variable, has been implemented in PAMCRASH using a user-defined subroutine in order to simulate the crushing of the crash-boxes. A simple approach is proposed to account for the bake-hardening treatment in numerical simulations. A good correlation between experimental and predicted mean crush forces is obtained.     

Parametric study and numerical analysis of empty and foam-filled thin-walled tubes under static and dynamic loadings

In this paper the crushing behavior of thin-walled tubes under static and dynamic loading is investigated. First, a finite element (FE) model for empty thin-walled tube was constructed and validated by available experimental and numerical data. The comparison between the FE results and the existing numerical solutions as well as the available experimental results showed good agreements. Next, a model for the foam was adopted and implemented in an in-house FE code. The implemented isotropic foam model was then used to simulate the behavior of foam-filled tubes under both static and dynamic loadings. Good agreement was observed between the results from the model with those obtained by analytical relations and experimental test data. The validated FE model was then used to conduct a series of parametric studies on foam-filled tapered tubes under static and dynamic loadings. The parametric studies were carried out to determine the effect of different parameters such as the number of oblique sides, foam density and boundary conditions on crushing behavior of rectangular tubes. The characteristic included deformed shapes, load–displacement, fold length and specific energy absorptions.     

Exploring success factors of video game communities in hierarchical linear modeling: The perspectives of members and leaders

Video games are enjoying fast-growing popularity, becoming a major component of young people’s social lives and leisure activities. Many players share information and conduct social interactions in virtual communities (VC). The current study sought to examine the relationships between members and leaders in such video game communities using a number of variables to describe the member (i.e., knowledge sharing, usefulness, enjoyability, off-site interaction, satisfaction, loyalty, and intention to use) and the leader (i.e., leader involvement). Based on a sample of 2227 members and 41 leaders in 30 video game communities, the research demonstrated the use of a two-level hierarchical linear modeling (HLM) to examine the relationships of VC leaders and members, appropriately adjusted for a nested structure. The results indicated that leaders who engage in higher levels of involvement in VC are more likely to have members who agree with and respond to the community. Furthermore, member- and leader-level factors were significantly associated with member satisfaction: knowledge sharing, usefulness, and enjoyability explained within-VC variance while leader involvement explained between-VC variance. Finally, member satisfaction demonstrated positive effects on both member loyalty and intention to use. The study further discussed the implications of these findings, offering direction for future research.     

A simple and fast asynchronous consensus protocol based on a weak failure detector

Summary. The Consensus problem is a fundamental paradigm for fault-tolerant asynchronous systems. It abstracts a family of problems known as Agreement (or Coordination) problems. Any solution to consensus can serve as a basic building block for solving such problems (e.g., atomic commitment or atomic broadcast). Solving consensus in an asynchronous system is not a trivial task: it has been proven (1985) by Fischer, Lynch and Paterson that there is no deterministic solution in asynchronous systems which are subject to even a single crash failure. To circumvent this impossibility result, Chandra and Toueg have introduced the concept of unreliable failure detectors (1991), and have studied how these failure detectors can be used to solve consensus in asynchronous systems with crash failures. This paper presents a new consensus protocol that uses a failure detector of the class . Like previous protocols, it is based on the rotating coordinator paradigm and proceeds in asynchronous rounds. Simplicity and efficiency are the main characteristics of this protocol. From a performance point of view, the protocol is particularly efficient when, whether failures occur or not, the underlying failure detector makes no mistake (a common case in practice). From a design point of view, the protocol is based on the combination of three simple mechanisms: a voting mechanism, a small finite state automaton which manages the behavior of each process, and the possibility for a process to change its mind during a round. Received: August 1997 / Accepted: March 1999     

Perceptions of fatherhood: Longitudinal reciprocal associations within the couple.

This longitudinal study examines reciprocal associations between maternal perceptions of paternal involvement and paternal perceptions of themselves as a father and of their relationship with the mother over the first 18 months after the birth of a first child, that is, during the transition to parenthood. Both members of intact heterosexual couples (n = 183) completed self-report questionnaires when their first child was two, five, and 18 months of age. Each assessment period included measures of fathers' perceptions of the importance of their parental identity, their parental self-efficacy, and their marital satisfaction, as well as mothers' perceptions of the quality and quantity of paternal involvement in child care. Results of cross-lag path analyses indicate that fathers' greater parental self-efficacy at two months predicts mothers' perceptions of greater paternal involvement at five months. Conversely, mothers' perceptions of greater paternal involvement at two months predict greater parental self-efficacy and marital satisfaction in fathers at five months. This study highlights the importance of the first few months after the birth of a child for perceptions of fatherhood within the couple. Results suggest that when couples become parents, new mothers and fathers mutually influence their respective perceptions relative to fatherhood. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Real-time assessment of fog-related crashes using airport weather data: A feasibility analysis

The effect of reduction of visibility on crash occurrence has recently been a major concern. Although visibility detection systems can help to mitigate the increased hazard of limited-visibility, such systems are not widely implemented and many locations with no systems are experiencing considerable number of fatal crashes due to reduction in visibility caused by fog and inclement weather. On the other hand, airports’ weather stations continuously monitor all climate parameters in real-time, and the gathered data may be utilized to mitigate the increased risk for the adjacent roadways. This study aims to examine the viability of using airport weather information in real-time road crash risk assessment in locations with recurrent fog problems. Bayesian logistic regression was utilized to link six years (2005–2010) of historical crash data to real-time weather information collected from eight airports in the State of Florida, roadway characteristics and aggregate traffic parameters. The results from this research indicate that real-time weather data collected from adjacent airports are good predictors to assess increased risk on highways.