Recess Pressure Research Articles

Design for static stiffness of hydrostatic bearings: double-action variable compensation of spool-type restrictors

Purpose – This paper is the third part of a serial studies for constant and variable compensations of the closed-type hydrostatic thrust bearings which has face-to-face recesses couple. The static stiffness of closed-type hydrostatic thrust bearings can then be obtained from the differentiation of recess pressure with respect to worktable displacement. The paper aims to discuss these issues. Design/methodology/approach – In this paper, the double-action restrictors of cylindrical-spool-type and tapered-spool-type are taken into consideration for variable compensation of hydrostatic bearings. Findings – The static stiffness in thrust direction of hydrostatic bearing is determined by the flow continuity equations that are formulated by film flow and compensation flow for each recess, respectively. The type selection and parameter determination of the double-action spool-type restrictors can be obtained from finding results of this study for maximum stiffness in design of hydrostatic bearings. Originality/value – This study reveals that the appropriate range of recess pressure ratio and design parameters of restrictors for the maximum stiffness can be obtained, the avoidance of negative stiffness is also provided.

The Experiences of Massachusetts Hospitals as Statewide Health Insurance Reform Was Implemented

Hospitals treat many uninsured patients and shoulder substantial amounts of uncompensated care. Health reform as implemented in Massachusetts, then, would be expected to bode well for hospitals as many people obtain coverage from private and public programs. We examined changes in Massachusetts hospital payer mix, unreimbursed costs of care for the uninsured and those in means-tested public programs, and overall financial condition for the period 2004 to 2010. Despite increases in coverage, unreimbursed costs for the uninsured and those in means-tested government programs did not decrease appreciably for Massachusetts hospitals over the study period. Major safety-net hospitals, which play a substantial role in serving the uninsured and Medicaid, had some initial easing of this burden but their financial situation weakened through 2010. The U.S. economic recession and Massachusetts budget pressures, which in part resulted from reform implementation, likely offset advantages hospitals experienced from reductions in the uninsured. Our analysis suggests that state actions in Massachusetts to change payment programs that the two major safety net hospitals relied on to support indigent care contributed to their financial difficulties.

Doing More with Less? Employee Reactions to Psychological Contract Breach via Target Similarity or Spillover during Public Sector Organizational Change

Many countries are facing the twin pressures of austerity and recession following the 2007–2008 global financial crisis. This paper uses the UK public sector and a major national announcement of budget cuts signalling extensive organizational cutbacks as its setting. We examine (a) whether organizational changes following the national announcement affect public sector employees' psychological contract breach, (b) whether employee reactions to psychological contract breach are consistent with the target similarity model and vary across foci, namely the organization, co‐workers and public service users, and (c) whether some of these relationships are moderated by job insecurity or public sector commitment. We collected longitudinal survey data before and after the announcement of budget cuts, using a sample of 340 employees from a range of public organizations and locations. Results largely confirm the hypotheses. Increases in organizational change predicted psychological contract breach, which in turn predicted decreases in contributions towards the organization; however, contributions towards co‐workers and public service users were unaffected, which can be explained with a target similarity, rather than a spillover, model. Furthermore, the relationship between breach and employee behaviours directed toward the public was moderated by job insecurity and public sector commitment.

What Skills Public Sector Leaders Needs in Times of Crises and Economic Recession?

In the context of financial constraints, limited resources, the increasing strategic demands and skill shortages, building solid skills in the public sector in Romania has become a pillar more important than ever.Management plays a vital role in every society, nation, public or private organization. Today we face a turbulent environment, the pressure of recession and if we are to develop sustainable public and private business then we need flexible and capable leaders. Of great interest in this work will be dialogue with the literature on possible answers to the question “What qualities or skills should have the public leader/manager and why?” How to lead a performing public organization today? “How to shape future professional leaders within public entities and how they can demonstrate their profesional performance in today difficult times?”

Influencing of Fluid-structure Interactions on Static and Dynamic Characteristics of Oil Hydrostatic Guideways

Oil hydrostatic guideways are widely applied in ultra-precision machine tools, the structural parts are often considered as rigid bodies without deformations in the process of design and calculation. In other words, the effects of the structural parts on the oil film thickness and the pressure distribution are ignored in the course of working. The fluid-structure interactions model of oil hydrostatic guideways with annular slit restrictors is established. This model is based on the dynamic Reynolds equation on the land, the elastic deformation equation of the upper slideway and the table dynamic equilibrium equation. The effects of fluid-structure interactions on the deformations, static and dynamic stiffness and settling time under the step load are explored. The results show that the deformations of the upper slideway increase linearly with recess pressure, the static and dynamic stiffness are decreased by the deformations, the settling time is extended by the deformations. Measured values of the static and dynamic stiffness agree well with the theoretical values with the deformations.

Using the Results of Economic Evaluations of Public Health Interventions: Challenges and Proposals

Abstract: Faced with the combined pressures of economic recession and growing healthcare costs, public health administrators recognize the value of using economic arguments to justify public health interventions. Given the expense and the time involved in conducting new economic evaluations, decision-makers regularly speculate on the possibility of using results from studies done in a different context. This article analyzes the potential for using the results of economic evaluations of public health interventions in contexts other than those in which the studies were done. More specifically, it sheds light on issues of quality and transferability of analyses for public health decision-making and offers practical proposals for increasing the transferability of studies.

"Austerity and its effects on change, psychological contracts, and employee contributions"

Many countries face the twin pressures of austerity and recession following the 2007-2008 global financial crisis. This paper uses the public sector as the setting for this investigation because a major UK national announcement of budget cuts signalled extensive organizational cutbacks. We examine longitudinally whether (a) organizational changes following the national announcement affect public sector employees’ psychological contract breach, (b), breach differentially affects three kinds of employee contributions: towards the organization, co-workers and service users (the public or “customers”), and, (c), whether some of these relationships are moderated by job insecurity or by public sector commitment. Longitudinal survey data collected before and after the national announcement are examined, using a sample of 340 employees from a wide range of public sector organizations and locations in the UK. Results largely confirm the hypotheses. Increases in organizational change predicted psychological contract breach, which in turn predicted decreases in contributions towards the organization; however, contributions directed at co-workers and service users were not affected, suggesting a target similarity, rather than a spillover, model. The relationship between breach and employee contributions in relation to public service was moderated by job insecurity and commitment to the public sector, demonstrating the importance of context in the process and outcomes of psychological contract breach during change.

21118 水静圧スラスト軸受におけるリセス圧力と軸受剛性の測定(GS-25【振動(2)】)

21118 水静圧スラスト軸受におけるリセス圧力と軸受剛性の測定(GS-25【振動(2)】)

Dynamic Characteristics of The Spool-Type Constant-Flow Valves

Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of a constant-flow valve can be constant in spite of the pressure changing in a recess. However the design parameters of this type valve must be specified. This paper analyzes the dynamic responses of the spool-type constant-flow valve that is designed as a spool-type restrictor but with matched preloading spring and supply pressure. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.

On the application of Rabinowitsch fluid model on an annular ring hydrostatic thrust bearing

Present theoretical analysis investigates the effects of centrifugal inertia on the performance of annular ring hydrostatic thrust bearings lubricated with non-Newtonian pseudoplastic lubricants—Rabinowitsch fluid model. Solution for pressure distribution has been obtained in the analysis. The influence of centrifugal inertia in the recess region is also considered by taking non-constant recess pressure. The load capacity and flow rate have been calculated numerically for various values of pseudoplastic parameter. In the limiting case in which there is an absence of pseudoplasticity, the results are compared with the pre-established results of Newtonian lubricants and found in good agreement.

On the Steady Performance of Annular Hydrostatic Thrust Bearing: Rabinowitsch Fluid Model

The present theoretical analysis investigates the simultaneous effect of lubricant inertia and non-Newtonian pseudoplastic lubricant (lubricant blended with viscosity index improver and viscosity thickener)–Rabinowitsch fluid model on the performance of externally pressurized annular hydrostatic thrust bearings. A close form solution is obtained for pressure distribution. The effect of centrifugal inertia on the pressure distribution in the recess region is considered by taking non-constant recess pressure under a hydrodynamic condition. The load capacity and flow rate have been numerically calculated for various values of viscosity index improver together with the centrifugal inertia effects. In the limiting case in which there is an absence of pseudoplasticity, the results are compared with the pre-established Newtonian lubricants and are found to be in good agreement.

Parameter identification for single‐action membrane‐type restrictors of hydrostatic bearings

PurposeThe purpose of this paper is to present the identification method of restriction parameter and deformation parameter for membrane‐type restrictors.Design/methodology/approachA worktable mounting on the open‐type hydrostatic bearing is utilized to calibrate recess pressures for regulating outlet pressures of restrictors by changing the load and then both restrictor parameters can be identified from the measurements of the inlet pressure, the outlet pressure, and the flow rate of a restrictor by minimizing the difference between measured and identified flow rates. Furthermore, the influences of supply pressure and restrictor designs on both parameters are also studied.FindingsAn identification method for single‐action membrane‐type (SAM) restrictors is obtained directly from experimental results. The measurements of inlet pressure, outlet pressure, and flow rate of the restrictor are substituted into the combined equations for minimization of error between measured and identified flow rates to be solved for restriction and deformation parameters. The identified results show that both parameters can be described by polynomial functions of supply pressure. Both polynomials are regressed by curve fitting from identified results.Originality/valueThe paper shows how to calibrate inlet and outlet pressures of restrictors for designing a hydrostatic bearing system by changing supply pressure and load applied on worktable for the measurements of both pressure and the flow rate of restrictor.

Forestry Actions to Tackle Climate Change and Its Impact on Carbon Emission and Employment Creation in China

Currently, climate change, sustainable development and employment problems have been the focus of world attention. This paper focuses on the forestry actions to climate change and its impact on employment in China on the basis of the qualitative analysis and case study. Firstly, it introduces the relationship between Low carbon development and employment; and it elaborates the main forestry actions framework to tackle climate change in China, i.e. Forestry carbon sinks, Forestry carbon sequestration and Forestry carbon substitution; it further introduces the main forestry practices, i.e. the implementation of forestry key project, carbon forestry and energy forestry; then analyzes the impact of forestry key actions on the employment and takes three Carbon pilot projects as cases study; Finally, it draws some conclusions and policy implications. Research results show that China’s forestry actions made positive contributions to tackle climate change through forestry carbon sinks, sequestration and substitution; it also produced positive influence on employment. Therefore, under the double pressures of global climate change and economics recession, it has important strategic significance in growing investment in forestry, vigorously increasing the capacity of forest carbon-sink and promoting forestry green employment.

Global Financial Crisis and Surgical Practice: The Greek Paradigm

Apart from the significant implications of recent financial crisis in overall health indices and mortality rates, the direct effect of health resources redistribution in everyday clinical practice is barely recognized. In the case of Greece, health sector reform and health spending cuts have already had a major impact on costly interventions, particularly in surgical practice. An increase in utilization of public health resources, lack of basic and advanced surgical supplies, salary deductions, and emerging issues in patient management have contributed to serious dysfunction of a public health system unable to sustain current needs. In this context, significant implications arise for the surgeons and patients as proper perioperative management is directly affected by reduced public health funding. The surgical community has expressed concerns about the quality of surgical care and the future of surgical progress in the era of the European Union. Greek surgeons are expected to support reform while maintaining a high level of surgical care to the public. The challenge of cost control in surgical practice provides, nevertheless, an excellent opportunity to reconsider health economics while innovation through a more traditional approach to the surgical patient should not be precluded. A Greek case study on the extent of the current situation is presented with reference to health policy reform, serving as an alarming paradigm for the global community under the pressure of a profound financial recession.

Design for static stiffness of hydrostatic plain bearings: constant compensations

PurposeThe paper aims to determine whether the type selection and parameters determination of the compensation are most important for yielding the acceptable or optimized characteristics in design of hydrostatic bearings.Design/methodology/approachThis paper utilizes the equations of flow equilibrium to determine the film thickness or displacement of worktable with respect to the recess pressure.FindingsThe stiffness due to compensation of constant‐flow pump increases monotonically as recess pressure increases. Also, the paper considers which is larger than that due to orifice compensation and capillary compensation at the same recess pressure ratio.Originality/valueThe findings show that the usage range of recess pressure and compensation parameters can be selected to correspond to the smallest gradient in variations of worktable displacement or film thickness.

Design for static stiffness of hydrostatic bearings: single‐action variable compensations

PurposeThis study aims to utilize the equations of flow equilibrium to determine the variations of film thickness or worktable displacement with respect to the recess pressure for both open‐ and closed‐type hydrostatic flat bearings. The static stiffness can be not only presented directly by these variations but also determined by the differentiation of flow equilibrium equations.Design/methodology/approachThe single‐action variable compensations of three types including cylindrical‐spool, conical‐spool and membrane restrictors are taken into consideration in this study. Specifically, this study presents that membrane restrictor and both spool restrictors with or without preload whilst considering initial opening.FindingsConsequently, the usage range of recess pressure and optimal parameters of appropriate compensation type can be obtained from maximum stiffness and also according to smallest gradient in variations of worktable displacement or film thickness.Originality/valueThis article studies the influences of single‐action variable compensations for its design varieties. The determination of stiffness comes from the differentiating recess pressure with respect to worktable displacement. The large and small positive stiffness correspond to a negative slope in steep and plain gradient, respectively; the negative stiffness and infinite stiffness are obtained by positive gradient and zero gradient, respectively, in the variations of film thickness. The finding results can be expressed further in the relationship between the static stiffness and the static load.

Effects of Injector Recess and Chamber Pressure on Combustion Characteristics of Liquid–Liquid Swirl Coaxial Injectors

Combustion characteristics such as combustion performance and combustion stability have been studied experimentally using a small liquid rocket thrust chamber with 19 liquid–liquid swirl coaxial injectors. Data were obtained from static pressure, temperature, and dynamic pressure sensors installed in propellant manifolds and the combustion chamber. While changing the recess length of the injector, characteristic velocity and pressure fluctuation data were collected and analyzed. In addition, chamber pressure was varied between 42 and 54 bar, which covers the sub- and supercritical pressures of oxygen. The results show that the longer recess length generally promotes combustion performance and the spray interaction between injectors in the multielement combustor increases the characteristic velocity. When the chamber pressure is above the critical pressure of oxygen, the recess length scarcely affects the pressure fluctuation. However, when the chamber pressure is below the critical pressure, the shift from external mixing to internal mixing of oxidizer and fuel sheets by the variation of recess length significantly degrades combustion stability and induces strong low-frequency instability. Accordingly, the effects of both recess length and operating chamber pressure must be taken into consideration when designing liquid–liquid swirl coaxial injectors.

Foresight in static stiffness of hydrostatic bearings with various compensations by film gradient versus recess pressure

PurposeThe purpose of this paper is to investigate the static stiffness of hydrostatic bearings with three constant compensations in types of constant‐flow pump, capillary and orifice, and both single‐action and double‐action variable restrictors with cylindrical‐spool, tapered‐spool, and membrane types by film gradient and recess pressure.Design/methodology/approachThis paper utilizes the equations of flow equilibrium to determine the variations of film thickness or displacement of loading table with respect to the varying of recess pressure. For a hydrostatic bearing whose recess pressures are controlled by compensations, the stiffness characteristics can be presented directly by these variations.FindingsThe usage range of recess pressure and compensation parameters should be selected to correspond to a variation with smallest gradient.Originality/valueThis paper proposes an extensive database as a critical requirement for the selection of types and parameters of the compensation as to yield the acceptable or optimized characteristics in design of hydrostatic bearings.

Foresight in Static Stiffness of Hydrostatic Bearings with Various Compensations by Film Gradient versus Recess Pressure

Foresight in Static Stiffness of Hydrostatic Bearings with Various Compensations by Film Gradient versus Recess Pressure

Changing career attitudes and corporate governance in Japan

Purpose – Japan is well known for having a strong stakeholder environment. However, a more than ten‐year recession and globalization pressures have put a strain on many aspects of the country's approach to corporate governance. The main goal of this paper is to investigate institutional change by examining the perceptions and expectations of an important stakeholder in the Japanese corporate governance arena.Design/methodology/approach – In this bottom‐up approach to corporate governance analysis, surveys were collected on employees’ perceptions of national and firm level developments in order to verify to what extent their views had an impact on their career management attitudes. Factor analysis and multiple regression techniques were used to test a number of research propositions.Findings – The results showed that although there is still strong support for a within‐company success orientation (stakeholder view) in Japan, there are a growing number of employees who prefer a personal career success orient...