On wavenumber spectra for sound within subsonic jets

This paper clarifies the nature of sound spectra within subsonic jets. Three problems, of increasing complexity, are presented. Firstly, a point source is placed in a two-dimensional plug flow and the sound field is obtained analytically. Secondly, a point source is embedded in a diverging axisymmetric jet and the sound field is obtained by solving the linearised Euler equations. Finally, an analysis of the acoustic waves propagating through a turbulent jet obtained by direct numerical simulation is presented. In each problem, the pressure or density field are analysed in the frequency-wavenumber domain. It is found that acoustic waves can be classified into three main frequency-dependent groups. A physical justification is provided for this classification. The main conclusion is that, at low Strouhal numbers, acoustic waves satisfy the d'Alembertian dispersion relation.Comment: 20 pages, 9 figure

Passion or delusion: middle managers constructing new meanings of work

Recently, organization scholars have called for a need to re-think managerial leadership so as to take into account the "mundane", the key activity of which is "influencing expectations, meanings, and values about what is desirable and necessary related to everyday work" (Sveningsson et. al., 2012: 84). In other words, mundane leaders can be seen as sense makers (Weick, 1995) and sense givers (Gioia and Chittipeddi 1991). Managerial leadership has also been described as event-driven actions arising mostly from unforeseen happenings (Holmberg and Tyrstrup, 2010). A study of site managers in construction depicted their leadership as a "muddling through", i.e. they skilfully solve problems as these inevitably crop up, and they try to be everywhere at the same time Styhre, 2012). We argue that muddling through also puts high demands on site managers' abilities and possibilities of coping with and balancing their work, family and personal life. The purpose of this paper is to explore what mundane leadership and muddling through actually mean for managerial leaders in construction from a wider perspective than their work. In other words, what does muddling through mean in terms of coping with work and family and life in general. This paper contributes empirical examples from 37 in-depth interviews with site managers, foremen and supervisor in a large number of construction organisations. We draw on practice theories to explore and analyse the data, and argue that mundane leaders are indeed both organizational sense makers and sense givers, the linkers of the strategic with the operational, the cohesion that generates coherence. All the site managers interviewed were passionate about their work, but deplored organisational and institutional constraints, which mostly obstructed rather than supported or facilitated their work. Sense-making and sense-giving roles demand presence, flexibility, experience, hindsight, judgment and improvisation, which in turn, and over time, often result in exhaustion and stress, and leave little energy over for family and life outside work. We conclude that the "mundane" activities of middle managers are far from trivial; they demand leadership competences that require fostering and nurturing. Today there is little support for middle-managerial leaders and little training of the competences that they need the nmost

Workaholics on site! Sustainability of site managers' work situations?

Site-managerial practice in construction has been depicted as a 'muddling through', being everywhere at the same time and skilfully solving problems as these crop up. The purpose of this paper is to explore work patterns and related well-being implications of site managers in construction. Drawing on the work-life stories of 21 site managers, which have been analysed using narrative analysis we argue that muddling through put high demands on these managers' abilities and possibilities of coping with and balancing their work situations. In all the accounts, several features of workaholism were identified as driving forces, often leading to negative well-being symptoms. The site managers were passionate about their work, but deplored organisational and institutional constraints, which mostly obstructed rather than supported or facilitated their work. This resulted in periods of exhaustion and stress, leaving little energy over for family and life outside work. We conclude that the warnings we perceive concerning the unsustainable work situations of site managers warrant further research

Exploring the work practices of site managers as processes of embodiment

In construction, site managerial work has often been depicted as 'muddling through', skilfully solving problems as these inevitably crop up and trying to be everywhere at the same time. This perspective seems to give precedence to structural conditions in the industry when explaining micro-level practice on construction sites. Recently, however, organisation scholars have highlighted a need to investigate managerial practices as these unfold in everyday work. This means we ought to take into account the actual work activities that influence expectations, meanings and values about what is desirable and necessarily relate to everyday work. The purpose of this paper is to further explore how practice enactment and outcomes are embedded in the lived, everyday work activities of real human beings working on site. The focus is on the work stories of two site managers, a man and a woman, in a large Swedish construction company. Drawing on their stories we take a critical stance towards the established view that certain structural and cultural conditions are strong and sufficient precursors to predict work practice outcomes. We propose instead that practices enacted on site can better be understood as various processes of embodiment

Coherence in a transmon qubit with epitaxial tunnel junctions

We developed transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The relaxation time T1 is .72-.86mu sec and the ensemble dephasing time T2 is slightly larger than T1. The dephasing time T2 (1.36mu sec) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker level splitting than observed in qubits with amorphous barriers in equivalent-size junctions. The qubit's inferred microwave loss closely matches the weighted losses of the individual elements (junction, wiring dielectric, and interdigitated capacitor), determined by independent resonator measurements

Method for forming articles having deep drawn portions from matted wood flakes

An article having non-planar portions, such as a material handling pallet, including a substantially flat deck member and a plurality of hollow leg members projecting integrally from the deck member, is molded as a one-piece unit from a loosely-felted mat formed from a mixture of resinous particle board binder and flake-like wood particles. The leg members are preformed in a separate preform mold or the article forming mold and the mat is deposited on the female die over mold cavities containing the preforms. When the article forming mold is closed, the mat and preforms are compressed into substantially the desired shape and size under temperature and pressure conditions which bond the wood particles of the mat and the preforms together to form a unitary structure.https://digitalcommons.mtu.edu/patents/1091/thumbnail.jp

Etch Induced Microwave Losses in Titanium Nitride Superconducting Resonators

We have investigated the correlation between the microwave loss and patterning method for coplanar waveguide titanium nitride resonators fabricated on Si wafers. Three different methods were investigated: fluorine- and chlorine-based reactive ion etches and an argon-ion mill. At high microwave probe powers the reactive etched resonators showed low internal loss, whereas the ion-milled samples showed dramatically higher loss. At single-photon powers we found that the fluorine-etched resonators exhibited substantially lower loss than the chlorine-etched ones. We interpret the results by use of numerically calculated filling factors and find that the silicon surface exhibits a higher loss when chlorine-etched than when fluorine-etched. We also find from microscopy that re-deposition of silicon onto the photoresist and side walls is the probable cause for the high loss observed for the ion-milled resonator

Validation of the effect of cross-calibrated GOES solar proton effective energies on derived integral fluxes by comparison with STEREO observations

The derivation of integral fluxes from instrument coincidence rates requires accurate knowledge of their effective energies. Recent cross calibrations of GOES with the high-energy-resolution Interplanetary Monitoring Platform (IMP) 8 Goddard Medium Energy Experiment (GME) (Sandberg et al., Geophys. Res. Lett, 41, 4435, 2014a) gave significantly lower effective energies than those currently used by the NOAA Space Weather Prediction Center to calculate solar proton integral fluxes from GOES rates. This implies systematically lower integral fluxes than currently produced. This paper quantifies the differences between the current and the cross-calibrated GOES integral fluxes and validates the latter. Care is taken to rule out the spectral resolution of the measurements or different integration algorithms as major contributors to differences in the magnitudes of the derived integral fluxes. The lower effective energies are validated by comparison with the independent, high-resolution observations by the STEREO Low-Energy Telescope (LET) and High-Energy Telescope (HET) during the December 2006 solar proton events. The current GOES product is similar to the >10 MeV integral fluxes recalculated by using the Sandberg et al. [2014a] effective energies but is substantially greater at higher energies. (The median ratios of the current to the recalculated fluxes are 1.1 at >10 MeV, 1.7 at >30 MeV, 2.1 at >60 MeV, and 2.9 at >100 MeV.) By virtue of this validation, the cross-calibrated GOES integral fluxes should be considered more accurate than the current NOAA product. The results of this study also demonstrate good consistency between the two long-term IMP 8 GME and STEREO LET and HET solar proton data sets