Variable force, eddy-current or magnetic damper

An object of the invention is to provide variable damping for resonant vibrations which may occur at different rotational speeds in the range of rpms in which a rotating machine is operated. A variable force damper in accordance with the invention includes a rotating mass carried on a shaft which is supported by a bearing in a resilient cage. The cage is attached to a support plate whose rim extends into an annular groove in a housing. Variable damping is effected by tabs of electrically conducting nonmagnetic material which extend radially from the cage. The tabs at an index position lie between the pole face of respective C shaped magnets. The magnets are attached by cantilever spring members to the housing

Hydrostatic bearing support

A hydrostatic bearing support system is provided which comprises a bearing housing having a polygonally configured outer surface which defines at least three symmetrically disposed working faces and a plurality of pressure plates, each of which is disposed relatively opposite a corresponding working face and spaced therefrom to define a gap therebetween. A hydrostatic support film is created in the gap for supporting the housing in spaced relationship to the pressure plates

Passive eddy-current damping as a means of vibration control in cryogenic turbomachinery

Lateral shaft vibrations produced by a rotating unbalance weight were damped by means of eddy currents generated in copper conductors that were precessing cyclicly in the gap formed by the pole faces of C-shaped, permanent magnets. The damper assembly, which was located at the lower bearing support of a vertically oriented rotor was completely immersed in liquid nitrogen during the test run. The test rotor was operated over a speed range from 800 to 10,000 rpm. Three magnet/conductor designs were evaluated. Experimental damping coefficients varied from 180 to 530 N sec/m. Reasonable agreement was noted for theoretical values of damping for these same assemblies. Values of damping coefficients varied from 150 to 780 N sec/m. The results demonstrate that passive eddy-current damping is a viable candidate for vibration control in cryogenic turbomachinery

Steady-state unbalance response of a three-disk flexible rotor on flexible, damped supports

Experimental data are presented for the unbalance response of a flexible, ball bearing supported rotor to speeds above the third lateral bending critical. Values of squeeze film damping coefficients obtained from measured data are compared to theoretical values obtained from short bearing approximation over a frequency range from 5000 to 31 000 cycles/min. Experimental response for an undamped rotor is compared to that of one having oil squeeze film dampers at the bearings. Unbalance applied varied from 0.62 to 15.1 gm-cm

Experimentally determined stiffness and damping of an inherently compensated air squeeze-film damper

Values of damping and stiffness were determined experimentally for an externally pressurized, inherently compensated, compressible squeeze-film damper up to excitation frequencies of 36,000 cycles per minute. Experimental damping values were higher than theory predicted at low squeeze numbers and less than predicted at high squeeze numbers. Experimental values of air film stiffness were less than theory predicted at low squeeze numbers and much greater at higher squeeze numbers. Results also indicate sufficient damping to attenuate amplitudes and forces at the critical speed when using three dampers in the flexible support system of a small, lightweight turborotor

Falling Behind: Americans' Access to Medical Care Deteriorates, 2003-2007

Presents survey results on access to medical care for the insured and the uninsured, the healthy and the ill, and for children in wealthy and poor families. Discusses causes of unmet needs such as rising costs and obstacles in the health system and plans

Three Criminals in Police uniform: reflections on radical feminist insight to challenge misogyny in policing

Violence Against Women and Girls (VAWG) is a growing global phenomenon along with the restriction of women’s rights over their own bodies and their appearance, in countries as disparate as America and Iran. The United Nations illustrated global VAWG prevalence and how it had peaked during COVID-19 (UN, 2020). At the same time there has been a rise in explicitly and overtly misogynistic ideas from influencers of boys and men like Andrew Tate. Tate extols the financial benefits to boys and men to follow his success of exploiting women and deceiving them into believing they are in relationships to control and abuse them emotionally, sexually and financially (Das, 2022). Concurrently in the UK we have a justice gap in relation to the successful prosecution of domestic and sexual violent offenders, and the criminal justice system which continues to blame and fail women generally (Stern, 2010; Stanko, 2023), and especially migrant women survivors, who are all also negatively impacted by cuts in legal aid since 2012 (Siddique, 2023). In the UK we have also seen increases in misogynistic crime offences undertaken by predatory criminal police officers. These offence types have included police perpetrated domestic violence and police use of online platforms in WhattsApp groups to share racist, homophobic and misogynistic messages with groups of other police officers. Some officers have also shared crime scene photographs of murdered women via this platform (Cunningham, 2021). In response there has been a lack of concerted, substantial institutional acknowledgement of the term ‘institutionalised’ in relation to racism or misogyny in policing. Instead of a recognition and acknowledgement of these offenders, there has been a denial of this toxic culture from within policing, followed by the adherence to the suggestion that this is simply a problem of a few rotten apples, to explain away these individual criminals in uniform. One example of this can be seen in the comments from Cressida Dick, the first female Commissioner of the Metropolitan Police Service (MPS), where she suggested the MPS had ‘an occasional bad ‘un’ (Topping, 2021). She also saw the term ‘institutional racism as an unhelpful (Cunningham, 2021) as has the new Commissioner, Rowley. Gavin Stephens, however, becomes most senior serving officer in 2024 to accept that discrimination in policing does in fact operate at a ‘fundamental level’ which may add pressure to Rowley this year to confront these issues and finally accept the terminology and the problem (Dodd, 2024a). Other institutions also contain and reproduce toxic misogynistic and racist culture, and research has also pointed to the clash of cultures within Higher Education (McCarthy and Taylor, 2023), and policing culture has been brought into Higher Education with the professionalisation agenda. Notwithstanding the acceptance that toxic cultures also exist within other organisations, within policing this culture poses particular problems given officers’ state sanctioned powers, credibility and discretion over citizens. For victim / survivors of domestic or sexual violence this culture will inform how the police respond to the offences they have been subjected to (Stern, 2010), and the same is true in relation to Black, Asian and Minority Ethnic citizens. The Centre for Women’s Justice in the UK submitted a successful super complaint against the police in 2019 in a legal effort to hold policing to account for police perpetrated VAWG (CWJ, 2019), however the toxic cultur

Studies on Emission Processes in Optically Pumped Mercury Vapor

Electron transitions in optically pumped mercury vapor emissio

Explaining External Support for Insurgent Groups

AbstractMany rebel organizations receive significant assistance from external governments, yet the reasons why some rebels attract foreign support while others do not is poorly understood. We analyze factors determining external support for insurgent groups from a principal-agent perspective. We focus on both the supply side, that is, when states are willing to support insurgent groups in other states, and the demand side, that is, when groups are willing to accept such support, with the conditions that this may entail. We test our hypotheses using new disaggregated data on insurgent groups and foreign support. Our results indicate that external rebel support is influenced by characteristics of the rebel group as well as linkages between rebel groups and actors in other countries. More specifically, we find that external support is more likely for moderately strong groups where support is more likely to be offered and accepted, in the presence of transnational constituencies, international rivalries, and when the government receives foreign support.</jats:p