Search results

Feathermoss is ubiquitous in the boreal forest and across various land‐cover types of the arctic and subarctic. A variety of affordable commercial sensors for soil moisture content measurement have recently become available and are in use in such regions, often in conjunction with fire‐susceptibility or ecological studies. Few come supplied with calibrations suitable or suggested for soils high in organics. Aims to test seven of these sensors for use in feathermoss, seeking calibrations between sensor output and volumetric water content.

Measurements from seven sensors installed in live, dead and burned feathermoss samples, drying in a controlled manner, were compared to moisture content measurements. Empirical calibrations of sensor output to water content were determined.

Almost all of the sensors tested were suitable for measuring the moss sample water content, and a unique calibration for each sensor for this material is presented. Differences in sensor design lead to changes in sensitivity as a function of volumetric water content, affecting the spatial averaging over the soil measurement volume.

The wide range of electromagnetic sensors available include frequency and time domain designs with variations in wave guide and sensor geometry, the location of sensor electronics and operating frequency.

This study provides information for extending the use of electromagnetic sensors to feathermoss.

A comparison of volumetric water content sensor mechanics and design is of general interest to researchers measuring soil water content. In particular, researchers working in wetlands, boreal forests and tundra regions will be able to apply these results.

The purpose of this paper is to discuss the recently developed multi-physics computational model for the conventional Gas Metal Arc Welding (GMAW) joining process that has been upgraded with respect to its predictive capabilities regarding the spatial distribution of the mechanical properties controlling the ballistic limit (i.e. penetration resistance) of the weld.

The original model consists of five modules, each dedicated to handling a specific aspect of the GMAW process, i.e.: electro-dynamics of the welding-gun; radiation-/convection-controlled heat transfer from the electric arc to the workpiece and mass transfer from the filler-metal consumable electrode to the weld; prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; and spatial distribution of the as-welded material mechanical properties. The model is upgraded through the introduction of the sixth module in the present work in recognition of the fact that in thick steel GMAW weldments, the overall ballistic performance of the armor may become controlled by the (often inferior) ballistic limits of its weld (fusion and heat-affected) zones.

The upgraded GMAW process model is next applied to the case of butt-welding of MIL A46100 (a prototypical high-hardness armor-grade martensitic steel) workpieces using filler-metal electrodes made of the same material. The predictions of the upgraded GMAW process model pertaining to the spatial distribution of the material microstructure and ballistic-limit-controlling mechanical properties within the MIL A46100 butt-weld are found to be consistent with general expectations and prior observations.

To the authors’ knowledge, the present work is the first reported attempt to establish, using computational modeling, functional relationships between the GMAW process parameters and the mechanical properties controlling the ballistic limit of the resulting weld.

The weld region obtained during friction stir welding (FSW) of metallic materials (including aluminum alloys) contains typically well-defined zones, each characterized by fairly unique microstructure and properties. The purpose of this paper is to carry out combined experimental and numerical investigations of the mechanical properties of materials residing in different weld zones of FSW joints of thick AA2139-T8 plates.

Within the experimental investigation, the following has been conducted: first, optical-microscopy characterization of the transverse sections of the FSW joints, in order to help identify and delineate weld zones; second, micro hardness field generation over the same transverse section in order to reconfirm the location and the extent of various weld zones; third, extraction of miniature tensile specimens from different weld zones and their experimental testing; and finally, extraction of a larger size tensile specimen spanning transversely the FSW weld and its testing. Within the computational investigation, an effort was made to: first, validate the mechanical properties obtained using the miniature tensile specimens; and second, demonstrate the need for the use of the miniature tensile specimens.

It is argued that the availability of weld-zone material mechanical properties is critical since: first, these properties are often inferior relative to their base-metal counterparts; second, the width of the weld in thick metallic-armor is often comparable to the armor thickness, and therefore may represent a significant portion of the armor exposed-surface area; and finally, modeling of the weld-material structural response under loading requires the availability of high-fidelity/validated material constitutive models, and the development of such models requires knowledge of the weld-material mechanical properties.

The importance of determining the mechanical properties of the material in different parts of the weld zone with sufficient accuracy is demonstrated.

The purpose of this paper is to present a conceptual framework for examining the impact of the COVID-19 pandemic on working women.

This conceptual paper on women in the formal workforce is grounded within the leadership and organization development literature.

The authors posit the COVID-19 pandemic and the subsequent instability in the US workforce, particularly among women and mothers, is effectively examined through the lens of punctuated equilibrium. Specifically, the widespread disruption initiated by the pandemic provides an opportunity for transformative change within organizations and society. Furthermore, working women impacted during this punctuated equilibrium are likewise positioned for transformation. The authors suggest the pandemic and its impact on the formal workforce can be leveraged for individual and organizational development as well as transformation, resulting in advancement toward self-authorship and increased equity within organizations, respectively.

This paper offers a novel integration and application of three leadership and organization development concepts: punctuated equilibrium, the self-authorship theory and Theory U, to better understand the impact of the COVID-19 pandemic on working women.

The purpose of this paper is to propose a computational approach to establish the effect of various flow drilling screw (FS) process and material parameters on the quality and the mechanical performance of the resulting FS joints.

Toward that end, a sequence of three distinct computational analyses is developed. These analyses include: (a) finite-element modeling and simulations of the FS process; (b) determination of the mechanical properties of the resulting FS joints through the use of three-dimensional, continuum finite-element-based numerical simulations of various mechanical tests performed on the FS joints; and (c) determination, parameterization and validation of the constitutive relations for the simplified FS connectors, using the results obtained in (b) and the available experimental results. The availability of such connectors is mandatory in large-scale computational analyses of whole-vehicle crash or even in simulations of vehicle component manufacturing, e.g. car-body electro-coat paint-baking process. In such simulations, explicit three-dimensional representation of all FS joints is associated with a prohibitive computational cost.

Virtual testing of the shell components fastened using the joint connectors validated the ability of these line elements to realistically account for the strength, ductility and toughness of the three-dimensional FS joints.

The approach developed in the present work can be used, within an engineering-optimization procedure, to adjust the FS process and material parameters (design variables) in order to obtain a desired combination of the FS-joint mechanical properties (objective function).

We address here how the U.S. neoliberal policy regime developed and how its reconstructed vision of modernization, which culminated, under the rubric of globalization, was neutralized by 9/11 and neoconservative geopolitics. We analyze the phases in the rise of neoliberalism, and provide a detailed map of its vision of global modernization at its high tide under Clinton. We also address how the Bush Doctrine's unilateral, preemptive polices and the consequent War on Terror and Iraq War eroded U.S. legitimacy as the globalization system's hegmon and shifted the discourse from globalization to empire. Cold War modernization theorists, neoliberal globalization advocates, and Bush doctrine neoconservatives all drew on an American exceptionalist tradition that portrays the U.S. as modernity's “lead society,” attaches universal significance to its values, policies, and institutions, and urges their worldwide diffusion. All three traditions ignore or diminish the importance of substantive equality and social justice. We suggest that consequent U.S. policy problems might be averted by recovery of a suppressed side of the American tradition that stresses social justice and holds that democracy must start at home and be spread by example rather than by exhortation or force. Overall, we explore the contradictory U.S. role in an emergent post-Cold War world.

The purpose of this paper is to propose a computational approach in order to help establish the effect of various self-piercing rivet (SPR) process and material parameters on the quality and the mechanical performance of the resulting SPR joints.

Toward that end, a sequence of three distinct computational analyses is developed. These analyses include: (a) finite-element modeling and simulations of the SPR process; (b) determination of the mechanical properties of the resulting SPR joints through the use of three-dimensional, continuum finite-element-based numerical simulations of various mechanical tests performed on the SPR joints; and (c) determination, parameterization and validation of the constitutive relations for the simplified SPR connectors, using the results obtained in (b) and the available experimental results. The availability of such connectors is mandatory in large-scale computational analyses of whole-vehicle crash or even in simulations of vehicle component manufacturing, e.g. car-body electro-coat paint-baking process. In such simulations, explicit three-dimensional representation of all SPR joints is associated with a prohibitive computational cost.

It is found that the approach developed in the present work can be used, within an engineering optimization procedure, to adjust the SPR process and material parameters (design variables) in order to obtain a desired combination of the SPR-joint mechanical properties (objective function).

To the authors’ knowledge, the present work is the first public-domain report of the comprehensive modeling and simulations including: self-piercing process; virtual mechanical testing of the SPR joints; and derivation of the constitutive relations for the SPR connector elements.

The primary aim of this chapter is to explore stigmatization, stress, and coping among adolescent mothers and to identify positive coping mechanisms that not only resist stigmatization but also generate positive affect.

Fifty-two pregnant and parenting adolescents in an urban county in the Midwestern United States were recruited to participate. A journaling tool was developed and used to allow participants to express their thoughts and concerns in a real-time, reflexive manner. Data were coded at different “nodes” or themes. Concepts, such as stigma, stress, strength, and empowerment were operationalized into key words and “themes” based on previous published literature. Key phrases were used to code the journaling data.

Adolescent mothers used positive reappraisal of life circumstances to create a positive self-image and resist the stress of stigma and parenting. Overcoming stereotypes and success in parenting were reappraised as “strength,” which allowed the young women to feel empowered in their caregiving role.

The chapter also contributes to the sociological literature on positive coping responses to stigma and stress. Indeed, very few studies have employed the sociological imagination of pregnant and parenting adolescents by describing not only their lives but also seeking their understanding and explaining their lives sociologically. This chapter also has direct implications for several health care providers, including nurses and social workers. For example, nurses and social workers are a vital part of the healthcare team for pregnant and parenting adolescents, and they often serve as the link between the adolescent, her family and significant others, and healthcare and social service agencies.

This chapter described the mechanisms that adolescent mothers use to cope with stress with a focus on how caregiving generates positive affect through the voices of these young mothers themselves. This chapter contributed to the sociological literature on stress and coping. In particular, our findings were also in line with the work of sociologist Antonovsky’s Sense of Coherence concept. SOC is a global measure that indicates the availability of, and willingness to use, adaptive coping resources as a key variable in maintaining health.

Against a background of increasing workload and external criticism, the purpose of this paper is to expose the indelible memories impressed on female police officers dedicated to investigating allegations of rape and sexual violence.

Participants (n = 15) were female police officers working in a specialist sexual offences investigation unit in a large English Metropolitan Police Force. A semi-structured interview was employed to elicit their experiences as an example of “extreme” police work. Interpretative phenomenological analysis was used to develop themes elucidating psychological and physical impacts on officers and their coping strategies.

Personal consequences were framed within the conceptualisation of secondary trauma. Emergent findings revealed profound and lasting vicarious traumatisation. Participants reported feelings of depression, anxiety, suicidal ideation, intrusive imagery, altered beliefs and cognitions as well as disrupted intimacy with partners. Coping adaptations included sensory shutdown, avoidance, dissociation and a reduction in victim care.

The findings support the need to consider occupational interventions to address risk factors associated with caseload, tenure, personal experience of neglect (e.g. in childhood), and the permeability of work and family boundaries for such exceptional policing tasks.

The paper contributes to a nascent literature on stress in “extreme” police work. The theoretical contribution is the focus on the emotional and physical aspects of vicarious trauma, which have been less well understood than cognitive aspects. The practice implications stress the need for targeted support activities given the profound psychological consequences of prolonged exposure to distressing material.

The purpose of this paper is to model a nacre-like composite material, consisting of tablets and polyurea tablet/tablet interfaces, B₄C. This composite material is being considered in the construction of the so-called backing-plate, a layer within a multi-functional/multi-layer armor system.

Considering the basic functions of the backing-plate (i.e. to provide structural support for the ceramic-strike-face and to stop a high-velocity projectile and the accompanying fragments) in such an armor system, the composite-material architecture is optimized with respect to simultaneously achieving high flexural stiffness and high ballistic-penetration resistance. Flexural stiffness and penetration resistance, for a given architecture of the nacre-like composite material, are assessed using a series of transient non-linear dynamics finite-element analyses. The suitability of the optimized composite material for use in backing-plate applications is then evaluated by comparing its performance against that of the rolled homogeneous armor (RHA), a common choice for the backing-plate material.

The results obtained established: a trade-off between the requirements for a high flexural stiffness and a high ballistic-penetration resistance in the nacre-like composite material; and overall superiority of the subject composite material over the RHA when used in the construction of the backing-plate within multi-functional/multi-layer armor systems.

This study extends the authors previous research on nacre-mimetic armor to optimize the architecture of the armor with respect to its flexural stiffness and ballistic-penetration resistance, so that these properties could be increased over the levels attained in the current choice (RHA) for the backing layer of multi-functional/multi-layer armor.