M. Grujicic, B. Pandurangan, G.M. Mocko, S.T. Hung, B.A. Cheeseman, W.N. Roy and R.R. Skaggs
Detonation of landmines buried to different depths in water‐saturated sand is analyzed computationally using transient non‐linear dynamics simulations in order to quantify impulse…
Abstract
Detonation of landmines buried to different depths in water‐saturated sand is analyzed computationally using transient non‐linear dynamics simulations in order to quantify impulse loading. The computational results are compared with the corresponding experimental results obtained using the Vertical Impulse Measurement Fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blast‐loading impulse. The structural‐dynamic/ballistic response of the Rolled Homogenized Armor (RHA) used in the construction of the VIMF witness plate and the remainder of the VIMF and the hydrodynamic response of the TNT high‐energy explosive of a mine and of the air surrounding the VIMF are represented using the standard materials models available in literature. The structural‐dynamic/ballistic response of the sand surrounding the mine, on the other hand, is represented using our recent modified compaction model which incorporates the effects of degree of saturation and the rate of deformation, two important effects which are generally neglected in standard material models for sand. The results obtained indicate that the use of the modified compaction model yields a substantially better agreement with the experimentally‐determined impulse loads over the use the original compaction model. Furthermore, the results suggest that, in the case of fully saturated sand, the blast loading is of a bubble type rather than of a shock type, i.e. the detonation‐induced momentum transfer to the witness plate is accomplished primarily through the interaction of the sand‐over‐burden (propelled by the high‐pressure expanding gaseous detonation by‐products) with the witness plate.
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M. Grujicic, B. Pandurangan, N. Coutris, B.A. Cheeseman, W. N. Roy and R.R. Skaggs
A large‐strain/high‐deformation rate model for clay‐free sand recently proposed and validated in our work [1,2], has been extended to sand containing relatively small (< 15vol.%…
Abstract
A large‐strain/high‐deformation rate model for clay‐free sand recently proposed and validated in our work [1,2], has been extended to sand containing relatively small (< 15vol.%) of clay and having various levels of saturation with water. The model includes an equation of state which represents the material response under hydrostatic pressure, a strength model which captures material behavior under elastic‐plastic conditions and a failure model which defines conditions and laws for the initiation and evolution of damage/failure in the material. The model was validated by comparing the computational results associated with detonation of a landmine in clayey sand (at different levels of saturation with water) with their computational counterparts.
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M. Grujicic, B. Pandurangan, I. Haque, B.A. Cheeseman, W.N. Roy and R.R. Skaggs
The kinematic response (including plastic deformation, failure initiation and fracture) of a soft‐skinned vehicle (represented by a F800 series single‐unit truck) to the…
Abstract
The kinematic response (including plastic deformation, failure initiation and fracture) of a soft‐skinned vehicle (represented by a F800 series single‐unit truck) to the detonation of a landmine shallow‐buried in (either dry or saturated sand) underneath the vehicle’s front right wheel is analyzed computationally. The computational analysis included the interactions of the gaseous detonation products and the sand ejecta with the vehicle and the transient non‐linear dynamics response of the vehicle. A frequency analysis of the pressure versus time signals and visual observation clearly show the differences in the blast loads resulting from the landmine detonation in dry and saturated sand as well as the associated kinematic response of the vehicle. It is noted that the dominant vehicle structural response to the blast is similar to the first torsional structural mode shape obtained through an eigenvalue analysis of the system. Tailoring the vehicle modal response may result in more desirable modes of failure.
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Beto Davison Avilés, Lori Russell-Chapin and Christopher J. Rybak
Professional school counselors have been in the public schools since the early 1900s. Fueled by the industrial revolution, the vocational guidance movement spawned the creation of…
Abstract
Professional school counselors have been in the public schools since the early 1900s. Fueled by the industrial revolution, the vocational guidance movement spawned the creation of high school guidance counseling programs. In 1907, Jesse B. Davis created one of the first vocational guidance programs at Central High School in Detroit, Michigan (Schmidt, 2014). In 1908, Frank Parsons, the father of vocational guidance, founded the Vocations Bureau that eventually became part of the Division of Education at Harvard University. These early efforts helped students develop vocationally, morally, and intellectually, and it would take nearly 70 years for children with exceptionalities to be similarly served in the public schools.
The purpose of this chapter is to explain the role of counselors in assisting students with exceptionalities. This will be examined by better understanding the counseling history, defining the terms of exceptionalities and transdisciplinary collaboration, and showcasing the many benefits of individual, group, and brain-based interventions.
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Francis X. Diebold and Glenn D. Rudebusch
Climate change is a massive multidimensional shift. Temperature shifts, in particular, have important implications for urbanization, agriculture, health, productivity, and…
Abstract
Climate change is a massive multidimensional shift. Temperature shifts, in particular, have important implications for urbanization, agriculture, health, productivity, and poverty, among other things. While much research has documented rising mean temperature levels, the authors also examine range-based measures of daily temperature volatility. Specifically, using data for select US cities over the past half-century, the authors compare the evolving time series dynamics of the average daily temperature (AVG) and the diurnal temperature range (DTR; the difference between the daily maximum and minimum temperatures). The authors characterize trend and seasonality in these two series using linear models with time-varying coefficients. These straightforward yet flexible approximations provide evidence of evolving DTR seasonality and stable AVG seasonality.
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The past few decades have witnessed a phenomenal progress in our understanding of employee mobility as a critical driver and consequence of various outcomes for individuals…
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The past few decades have witnessed a phenomenal progress in our understanding of employee mobility as a critical driver and consequence of various outcomes for individuals, organizations, industries, and economies. In the process, researchers have tackled several important issues in conducting empirical research on employee mobility. This chapter provides a critical discussion of the extant literature focusing on five broad areas: identification of mobility, timing of mobility, outcomes of mobility and their operationalization, model identification, and other related issues. In doing so, this article identifies some of the empirical choices and methodologies adopted in prior mobility studies, evaluates those practices, and suggests areas of improvements for the practice. It is hoped that future studies will benefit from this chapter's insight by building on the best practices from the literature while continuously and successfully tackling the issues that have been challenging the researchers on this increasingly important topic of scholarly inquiry.
Leadership behaviour of R&D project managers (RDPMs) is a matter of ongoing interest, as they require a number of traits in order to potentially influence the delivery of…
Abstract
Purpose
Leadership behaviour of R&D project managers (RDPMs) is a matter of ongoing interest, as they require a number of traits in order to potentially influence the delivery of projects. However, little empirical evidence exists on factors explaining the traits of RDPMs, making it difficult for industry managers to develop tailored strategies and criteria for selecting people with right skills and behaviours. The purpose of this paper is to fill this gap in knowledge.
Design/methodology/approach
The authors test 45 traits with data from a survey of 208 RDPMs, using exploratory factor analysis to establish factors of RDPMs’ traits and the associated measurement items.
Findings
The study finds that selected 45 traits can be consolidated in a set of higher order variables/factors that RDPMs need to have including creativity, reasoning and learning; risks and failure acceptance; analytical and originality attributes; realistic and objective approach among others.
Research limitations/implications
The study shows that traits have strong inter-relationship represented by empirically robust underlying factors.
Practical implications
Practically, the results will help industry mangers in implementing tailored strategies in consolidated areas (as identified through factors) and be more effective in skills and competencies development of research and development staff and potentially save costs on human inventory management.
Originality/value
The study empirically established new managerial and leadership behavioural factors.
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Valentina La Porta and Matteo Migheli
This paper aims to study the effects of innovation on the profitability of large wineries. In particular, organic growth is evaluated versus external growth.
Abstract
Purpose
This paper aims to study the effects of innovation on the profitability of large wineries. In particular, organic growth is evaluated versus external growth.
Design/methodology/approach
Data from balance sheets over more than a decade are used. The analysis is limited to large Italian wineries to include firms that constantly invest in R&D in the sample. The analysis focuses on 25 Italian wineries observed over eight years. Panel data estimation is used to analyse these data.
Findings
The paper shows that investments in R&D increase the profitability of innovative wineries in the long run but decrease it in the short run. Moreover, because of financial constraints, some wineries may invest too few resources in R&D.
Research limitations/implications
The main limitation is that the focus is restricted to large wine producers, while many small producers that do not generally invest in R&D exist in the market. The practical implication is that governments should support R&D investments of wineries.
Originality/value
The main contributions are to show empirically the effects of investing in R&D on the profitability of large wineries and to highlight the possible presence of severe financial constraints, which require policy interventions.