Holographic measurement of drop-on-demand drops in flight

The analysis of images of ink drops in flight can provide information about jet straightness, drop velocity and volume. However trade-offs between field of view, optical and digital resolution and other factors such as depth of field and optical distortion, limit the accuracy and amount of information available from a single image. In-line, digital holograms of drops in flight can capture information from fields of view at least as large as the area of the digital sensor. Using mathematical reconstruction techniques particularly suited to sparse, small objects of regular geometry the accuracy of measurement can potentially be submicrometer on drop position and diameter. This paper describes our experimental apparatus, hologram reconstruction techniques and the results of experiments on imaging drops. We also discuss techniques to improve the accuracy of the technique in the direction of the optical axis

Aerodynamic effects in ink-jet printing on a moving web

This work was sponsored by EPSRC grant number RG5560

Jetting, in-nozzle meniscus motion and nozzle-plate flooding in an industrial drop-on-demand print head

The state of the ink film at and near the nozzles of a drop-ondemand(DoD) print head during jetting has a direct impact on printing performance and reliability. We have developed highspeed imaging apparatus and analytical techniques to investigate the ink film dynamics on an industrial print head nozzle-plate in real-time. In addition to a direct correlation between the jet emergence velocity and drive voltage, drive-dependent variations in the oscillation of the ink meniscus in adjacent nozzles were also observed. Using a ray-tracing model to analyze the meniscus shape, the meniscus oscillations for both printing and nonprinting nozzles were found to be complex and involve elements such as pre-oscillation and high-order surface waves. The flooding of non-firing nozzles, deliberately caused by the application of maximum drive voltage to a neighboring nozzle, has been recorded and analyzed dynamically. The build-up of fluid in an annulus around the nozzle (flooding rate) has been characterized and compared with models for the net ink flow through the nozzle

Dependence of drop speed on nozzle diameter, viscosity and drive amplitude in drop-on-demand ink-jet printing

Results of recent experiments and numerical simulations are presented, which have been used to establish empirical rules for the dependence of drop speed on nozzle diameter and drive amplitude for Newtonian and non-Newtonian fluids printed with a range of different ink-jet print-head technologies. Experiments were carried out with Xaar, MicroFab and Spectra Dimatix print heads and with solutions of polystyrene in diethyl phthalate as model fluids. These results are compared with predictions from recent numerical codes developed by collaborators in the University of Leeds, and from simple models for drop-on-demand fluid jetting resulting from physical law

Imbibition dynamics of nano-particulate ink-jet drops on micro-porous media

Ink-jet printing of nano-metallic colloidal fluids on to porous media such as coated papers has become a viable method to produce conductive tracks for low-cost, disposable printed electronic devices. However, the formation of well-defined and functional tracks on an absorbing surface is controlled by the drop imbibition dynamics in addition to the well-studied post-impact drop spreading behavior. This study represents the first investigation of the realtime imbibition of ink-jet deposited nano-Cu colloid drops on to coated paper substrates. In addition, the same ink was deposited on to a non-porous polymer surface as a control substrate. By using high-speed video imaging to capture the deposition of ink-jet drops, the time-scales of drop spreading and imbibition were quantified and compared with model predictions. The influences of the coating pore size on the bulk absorption rate and nano-Cu particle distribution have also been studied

Double Down-and-Out: The Connection Between Payday Loans and Bankruptcy

This Article reviews the literature on the debate regarding the causal relationship between filing for bankruptcy and the use of payday loans but does not weigh in on the subject. Rather, it uses these studies, as well as a general discussion of bankruptcy filing and payday loans, as a backdrop for analyzing new data regarding the correlation between bankruptcy filing and the use of payday loans. This Article reports on an empirical study conducted in the state of New Mexico that measures rates of payday loan use among bankruptcy debtors from a large sample of publicly available bankruptcy data. Part I of this Article discusses the payday loan industry, its business model, how the loans work, and who the likely payday lending customer is. Part II reviews the current literature regarding the connection between payday loans and bankruptcy, and suggests some ways in which the existing literature falls short of fully answering the question of whether payday lending causes bankruptcy filing. Part III describes the new empirical study from New Mexico. This Article describes the method used to conduct this study as well as its results. In summary, our data show that from 2007 to 2009, 18.9 percent of bankruptcy debtors in New Mexico reported using payday loans. Compared to the use of payday loans reported in other studies among the general population, as well as past studies on payday loan use among bankruptcy debtors, this rate of usage is extremely high. Moreover, the correlation between bankruptcy and payday loans seems to be getting stronger, as the use of these loan products appears to be growing. We find that almost double the percentage of bankruptcy debtors reported using payday loans from 2007 to 2009, than from 2000 to 2002. Part IV of this Article concludes that while one cannot be certain that there is a causal connection between filing for bankruptcy and using payday or other short-term loans, there is a strong correlation between bankruptcy filing and payday loan use. If the increasing use of payday loans is seen as a problem, we conclude that the problem appears to be growing, despite efforts by states to cut down on the use of these loans and to curb the use of multiple loans at one time. In fact, the usage of multiple payday loans at one time also has increased drastically, as recent bankruptcy debtors, whether individuals or families, report using far more of these types of loans simultaneously than in the past. All of this indicates that the use of multiple loans at one time is increasing, a problem states are grappling with but apparently are not solving

Emergency Department Clinicians’ Attitudes Toward Opioid Use Disorder and Emergency Department-initiated Buprenorphine Treatment: A Mixed-Methods Study

Introduction: Emergency department (ED) visits related to opioid use disorder (OUD) have increased nearly twofold over the last decade. Treatment with buprenorphine has been demonstrated to decrease opioid-related overdose deaths. In this study, we aimed to better understand ED clinicians’ attitudes toward the initiation of buprenorphine treatment in the ED.Methods: We performed a mixed-methods study consisting of a survey of 174 ED clinicians (attending physicians, residents, and physician assistants) and semi-structured interviews with 17 attending emergency physicians at a tertiary-care academic hospital.Results: A total of 93 ED clinicians (53% of those contacted) completed the survey. While 80% of respondents agreed that buprenorphine should be administered in the ED for patients requesting treatment, only 44% felt that they were prepared to discuss medication for addiction treatment. Compared to clinicians with fewer than five years of practice, those with greater experience were less likely to approve of ED-initiated buprenorphine. In our qualitative analysis, physicians had differing perspectives on the role that the ED should play in treating OUD. Most physicians felt that a buprenorphine-based intervention in the ED would be feasible with institutional support, including training opportunities, protocol support within the electronic health record, counseling and support staff, and a robust referral system for outpatient follow-up.Conclusion: ED clinicians’ perception of buprenorphine varied by years of practice and training level. Most ED clinicians did not feel prepared to initiate buprenorphine in the ED. Qualitative interviews identified several addressable barriers to ED-initiated buprenorphine

Comparing COP Optimization with Maximizing the Coefficient of System Performance for Refrigeration Systems in Supermarkets

In recent years the energy usage of supermarkets, in particular that of their refrigeration systems, has been investigated using a variety of approaches, such as floating pressure set points and integrating the heating and refrigeration systems. Something which has not yet attracted much attention is the energy consumption of the dry condenser fans in refrigeration systems. This is surprising as it has been shown for comparable installations that including the energy consumption of these fans when optimizing the system efficiency was beneficial. To address this deficit, _COP_ maximization has been compared to optimizing the Coefficient of System Performance (_COSP_). The simple refrigeration system used for this investigation was based on a commercially available R404A/CO2 system comprising the basic components, with the condenser having extractor fans. The results show that, when the outdoor temperature is below about 15°C, there is no observable difference between these two approaches. However, when the ambient temperature increases beyond this threshold, the control method which optimizes _COSP_ is significantly better for part load conditions. This indicates that maximizing the _COP_ can lead to a sub-optimal system in terms of energy consumption under part load conditions. When the refrigeration system is at its full load point, however, both approaches produce similar results again

InGaN nano-ring structures for high-efficiency light emitting diodes

A technique based on the Fresnel diffraction effect for the fabrication of nano-scale site-controlled ring structures in InGaN/GaN multi-quantum well structures has been demonstrated. The ring structures have an internal diameter of 500 nm and a wall width of 300 nm. A 1 cm-1 Raman shift has been measured, signifying substantial strain relaxation from the fabricated structure. The 9 nm blueshift observed in the cathodoluminescence spectra can be attributed to band filling and/or screening of the piezoelectric field. A light emitting diode based on this geometry has been demonstrated. © 2005 American Institute of Physics.published_or_final_versio

The nature of the SDSS galaxies in various classes based on morphology, colour and spectral features -- I. Optical properties

We present a comprehensive study of the nature of the SDSS galaxies divided into various classes based on their morphology, colour, and spectral features. The SDSS galaxies are classified into early-type and late-type; red and blue; passive, HII, Seyfert, and LINER, returning a total of 16 fine classes of galaxies. We examine the luminosity dependence of seven physical parameters of galaxies in each class. We find that more than half of red early-type galaxies (REGs) have star formation or AGN activity, and that these active REGs have smaller axis ratio and bluer outside compared to the passive REGs. Blue early-type galaxies (BEGs) show structural features similar to those of REGs, but their centres are bluer than REGs. HII BEGs are found to have bluer centres than passive BEGs, but HII REGs have bluer outside than passive REGs. Bulge-dominated late-type galaxies have red colours. Passive red late-types are similar to REGs in several aspects. Most blue late-type galaxies (BLGs) have forming stars, but a small fraction of BLGs do not show evidence for current star formation activity. Differences of other physical parameters among different classes are inspected, and their implication on galaxy evolution is discussed.Comment: 16 pages, 10 tables, 16 figures; accepted for publication in MNRA