Slot Width Ratio Research Articles

Video telescope operating monitor-assisted surgery is equivalent to conventional surgery in treatment of cervical intervertebral disc herniation in dogs.

To compare the use of the video telescope operating monitor (VITOM) and use of a conventional unassisted surgical method for treatment of cervical intervertebral disc herniation in dogs. 39 dogs with cervical intervertebral disc disease. Prospective study. Dogs were prospectively nonrandomly assigned to either the VITOM (n = 19) or conventional surgery (20) group depending on VITOM system availability. Signalment and preoperative neurologic status were recorded for all dogs. Preoperative and postoperative CT myelography was performed to compare intervertebral space location, spinal cord dimensions at the decompression level, ventral slot dimensions, and residual disc material. Surgical complications and postoperative neurologic outcomes were recorded. Data were compared between the 2 groups using fixed-effects or mixed-effects models to consider double reading of CT myelography images. No significant differences were noted between the 2 groups regarding the decompression ratio (P = .85), vertebral length body ratio (P = .13), ventral slot width ratio (P = .39), residual disc material (P = .30), and sinus bleeding (P = .12). No significant differences were found between the 2 groups regarding postoperative neurologic grade (P = .17). VITOM-assisted ventral slot decompression is equivalent to conventional surgery in treatment of cervical intervertebral disc herniation in dogs. The use of VITOM remains a good alternative to the conventional surgical method.

Experimental study on distributed aerodynamic forces of parallel box girders with various slot width ratios and aerodynamic countermeasures during vortex-induced vibration

The widespread adoption of parallel box girders in bridge engineering is attributed to their superior traffic-bearing capacity and streamlined construction methodologies. Nevertheless, these structures are confronted with exacerbated vortex-induced vibration (VIV) challenges stemming from aerodynamic interference and intricate vortex shedding phenomena between the girders. In the present study, a series of extensive wind tunnel experiments are conducted to scrutinize the VIV behavior of parallel box girders with diverse slot width ratios, taking into account both sectional model oscillations and surface pressure. The mean pressure coefficient, fluctuating pressure coefficient, time-frequency attributes of the distributed aerodynamic force, and the contribution value of distributed aerodynamic force to vortex-driven force are meticulously analyzed and compared to ascertain the impact of slot width ratio on VIV. Drawing on the empirical findings, we put forth and assess aerodynamic countermeasures aimed at augmenting the VIV performance of parallel box girders. Furthermore, the control mechanism for VIV is studied with respect to alterations in the distributed aerodynamic force. Our investigation reveals significant aerodynamic interference between parallel box girders featuring distinct slot width ratios. The frequency multiplication effect and signature turbulence in the aerodynamic force amidst VIV is observed, although the oscillation characteristics persist primarily at a singular frequency. The VIV of parallel box girders is instigated by the marked fluctuating pressure on the upper surface in proximity to the slot side and the inclined web of the leeward girder, accounting for the heightened severity and intricacy of VIV in these configurations as opposed to single closed-box girders. The synergistic implementation of skirt plates and wind fairings or winglets efficaciously eradicates the root causes of VIV in the original girders and even transmutes the contribution value of the distributed aerodynamic force from positive to negative, thereby suppressing VIV.

Accuracy of a 3-dimensionally printed custom endoscopy port for minimally invasive ventral slot decompression in dogs: A cadaveric study.

To evaluate the accuracy of a 3-dimensionally (3D)-printed custom endoscopy port (3DEP) for minimally invasive cervical ventral slot decompression. Cadaveric study. Fifteen cadavers of dogs weighing between 3.1 and 34.4kg. Minimally invasive cervical ventral slots were created using a 3DEP and an endoscopic system at the C3-C4 intervertebral disc space in each dog by 1 experienced and 1 inexperienced surgeon. Postoperative computed tomography was performed to compare the planned and postoperative screw trajectories (angle, entry point, exit point, and length of the screw entering the spinal canal) and quantify slot formation dimensions. Thirty screws were inserted in 30 vertebral bodies. Mean screw angle deviation was less than 2.5°, entry and exit point deviation was less than 1.6 mm, and length of the screw entering the spinal canal was less than 0.6 mm. No differences were identified between the experienced and inexperienced surgeons. Ventral slot length ratio was 30.15 ± 1.86 for the experienced surgeon and 29.38 ± 1.61 for the inexperienced surgeon (p = .372). The mean ventral slot width ratio was 45.60 ± 1.80 for the experienced surgeon and 47.20 ± 1.54 for the inexperienced surgeon (p = .261). Screw positioning and creationofventral slots were accurately performed using the 3DEP by both inexperienced and experienced surgeons. The use of a 3DEP for minimally invasive cervical ventral slot decompression may be an alternative to the conventional ventral slot in dogs. Additional studies are needed to evaluate efficacy and safety.

Flow-field characteristics of a synthetic jet impinging on a circular cylinder in a free and constrained environment

The flow field of a synthetic jet (SJ) impinging on a circular cylinder has been investigated while varying jet-cylinder separation distances in a free and constrained environment. For the free environment case, the cylinder was placed in the SJ flow field in a quiescent environment, and its separation distance downstream from the slot exit was varied. Whereas for the constrained environment case, two parallel sidewalls were mounted along the shorter side of the slot, and the cylinder was placed between these sidewalls. The slot width (w = 6.4 mm) and aspect ratio (25) were kept constant for both cases. The experimental results for the SJ impinging on a circular cylinder showed that the flow-field behavior differs significantly from that of a cylinder in uniform flow and is largely affected by the jet-cylinder separation distance and the operating environment, i.e., free or constrained. The plots of the pressure distribution and normalized standard deviation of the fluctuating pressure around the cylinder surface revealed higher flow fluctuations associated with SJ impingement. The flow visualization and the hot wire measurements further unveiled that no obvious vortex shedding occurs in the cylinder wake. However, evidence for vortex dipoles rising from the cylinder surface was found, on either side of the cylinder (perpendicular to the flow direction).

Combustion Performance of Methane/Air in a Micro Combustor Embedded Hollow Hemispherical Slotted Bluff Body

With the rapid development of micro-energy power systems, the performance of micro-combustors as key components is in urgent need of further improvement. Aimed at enhancing combustion performance, a hollow hemispherical bluff body was used to analyze the methane combustion process. In this paper, we exploited the detailed reaction mechanism of methane/air with a laminar finite-rate model; the numerical analysis of methane combustion in the micro-combustor was carried out by Ansys Fluent software. The combustion, flow and thermal characteristics of the micro-combustor embedded with a hollow hemisphere bluff body (MCEHB) and the micro combustor embedded with a slotted hollow hemisphere bluff body (MCESHB) are compared, and the effect of slot width ratio on the combustion characteristics and thermal performance is discussed in detail. The results showed that the bluff body slotting treatment is not only beneficial to improving the velocity and temperature distribution behind the bluff body but also can improve the conversion rate of methane, especially at high inlet velocities. However, the conversion rate of methane is also affected by the slot width. When the slot width ratio below 0.5, the slot width corresponding to the peak methane conversion increased with the inlet velocity. Moreover, the bluff body slotting treatment can improve the wall temperature distribution, meanwhile expanding the high temperature area at the inner wall, thereby reducing the wall temperature fluctuation in the rear part of the micro-combustor. In addition, the optimal slot width ratio B increases with the inlet velocity. Since the inlet velocity is lower than 0.5 m/s, the optimal slot width ratio B is in the range of 0.3–0.375. However, as the inlet velocity exceeds 0.5 m/s, the optimal slot width ratio B moves to the range of 0.375–0.553. Furthermore, both large and small slot widths bring obvious temperature fluctuations to the micro combustor; the uneven wall temperature distribution phenomenon is detrimental to working performance. Therefore, the slot width ratio B of 0.375 only brings slight temperature fluctuations, indicating this is an optimal slot width ratio that should be chosen. This work has reference value for optimizing the design of the bluff body structure and improving the combustion performance of methane in the micro combustor.

Computational Performance Analysis of a Two-slotted Bucket Savonius Rotor

The objective of the current computational study is to predict the performance output of a modified two-bucket Savonius rotor. Each bucket consists of three arc-type blades of different radius which is determined by the slot width ratio, in the range of 0.05 to 0.15 and the slot central angle, in the range of 0 to 20 deg. Nine configurations are designed with a fixed rotor diameter and a variable slot width and slot central angle, aiming to resolve the performance output and investigate the effect of the two previous parameters on the power and the static torque coefficients. The commercial CFD package Fluent® is used to solve the unsteady Reynolds-Averaged Navier-Stokes equations, along with Spalart-Allmaras turbulence model. Initially, a standard Savonius rotor, was used to validate the computational procedure using experimental results available in literature. Next, the same validated model is used to resolve the designed slotted bucket configurations. The performance of the examined slotted bucket configurations indicates improved self-starting characteristics, but a lower power coefficient compared with the solid bucket Savonius rotor. Lower values of slot width ratio have improved output performance while the slot central angle, does not greatly affect the overall performance of slotted bucket rotor

Jet direction control using secondary flows

In recent years, studies on the fundamental principle of thrust vectoring using jets have been conducted with the aim of application to next-generation aircraft. Consequently, the improvement of aircraft motion performance is expected. Previously, a method using secondary flow with a Coanda surface was proposed for the direction control of the primary jet, and some valuable results were reported. The effect of ejection or suction on the traveling direction of the primary jet was examined. However, as many physical quantities dominate the phenomenon in this complicated situation, parametric studies are insufficient. The present study is a fundamental study of fluidic thrust vectoring. The effect of secondary injection or suction flow near the Coanda surface on the travel direction of primary jets was investigated parametrically using the momentum ratio, nozzle width ratio, etc. without changing the nozzle geometry. A larger deflection of the primary jet was observed because of the suction rather than ejection at the same momentum ratio. Furthermore, the effect of the slot width ratio on the dead zone where the traveling direction of the second jet does not depend on the momentum of the secondary flow was studied.

Experimental and numerical study of the effect of perimeter jet enhancement on the capture velocity of a rectangular exhaust hood

Using a radial jet at the outer edge of a circular exhaust hood can effectively reduce the velocity attenuation in front of the exhaust hood. The velocity distribution, especially the centerline velocity, is a key parameter in the effective design and use of an exhaust hood. In this paper, based on the derivation of the prediction formula of the suction velocity, the study of the suction velocity of jet-enhanced rectangular exhaust hood that considers the jet enhanced, viscous and geometrical effects is presented via the experimental and numerical methods. To understand the suction velocity distribution, the centerline velocity is investigated by varying the jet velocity, jet angle, jet slot width, exhaust rate and aspect ratio of the hood. It is found that the critical jet velocity condition is a most effective and energy-saving working condition for this kind of hood. Based on the critical jet velocity working condition, reducing the jet angle instead of increasing the exhaust rate is an airflow-rate-saving way to further increase the centerline velocity at a relatively large distance away from the hood opening. Calculation equations for the prediction of the centerline velocity of rectangular jet-enhanced exhaust hood are proposed. The error of the formula is proven to be within 10%, and its application range is proposed. The outcome of this work can help to efficiently design and use this type of energy-saving exhaust hood in residential and industrial local ventilation applications.

Flow Analysis of a Symmetrical Channel with Multiple Jets at the Upper Wall

The objective of this study is to analyze experimentally and numerically the flow characteristics of a symmetric channel arisen from flow modeling of the blade cooling problem. The two ends of the flat channel are open and five evenly spaced air jets of equal strength at the upper wall configure a symmetrical flow around the mid-slot symmetry axis. The parameters that govern the flow characteristics of such a system are; the channel height, the jet spacing, and the jet velocity. In the analysis, the slot width is kept constant, but the channel height to slot width ratio ( ), and the slot spacing ratio ( ) vary in the range of 1-3 and 2-4 respectively. In addition, the flow Reynolds number (Re) is altered in a range between 1500 and 10500 for each channel geometry of nine combinations. In experiments, the pressure distributions by an electronic micro-manometer, and the velocity profiles by a hot-wire anemometry system are measured. In numerical approach, the realizable turbulence model with enhanced wall treatment is used for the turbulence computations. Comparisons with the experimental data obtained under isothermal conditions allow evaluation of the performance of the numerical model. The results show that the channel height is the dominant parameter that affects the flow characteristics and a correlation is proposed for determining the pressure drop coefficient of the injection section.

A Simple and Unified Linear Solver for Free-Surface and Pressurized Mixed Flows in Hydraulic Systems

A semi–implicit numerical model with a linear solver is proposed for the free-surface and pressurized mixed flows in hydraulic systems. It solves the two flow regimes within a unified formulation, and is much simpler than existing similar models for mixed flows. Using a local linearization and an Eulerian–Lagrangian method, the new model only needs to solve a tridiagonal linear system (arising from velocity-pressure coupling) and is free of iterations. The model is tested using various types of mixed flows, where the simulation results agree with analytical solutions, experiment data and the results reported by former researchers. Sensitivity studies of grid scales and time steps are both performed, where a common grid scale provides grid-independent results and a common time step provides time-step-independent results. Moreover, the model is revealed to achieve stable and accurate simulations at large time steps for which the CFL is greater than 1. In simulations of a challenging case (mixed flows characterized by frequent flow-regime conversions and a closed pipe with wide-top cross-sections), an artificial slot (A-slot) technique is proposed to cope with possible instabilities related to the discontinuous main-diagonal coefficients of the linear system. In this test, a slot-width sensitivity study is also performed, and the suitable slot-width ratio (ε) for the linear solver is suggested to be 0.05–0.1.

Comparative Study of Air-Gap Field Modulation in Flux Reversal and Vernier Permanent Magnet Machines

In this paper, the torque production mechanisms of flux-reversal permanent magnet (FRPM) machine and Vernier permanent magnet (PM) machine are analyzed and compared based on air-gap field modulation. Working harmonics of PM magnetomotive force (MMF) and air-gap permeance in two machines are analytically identified and compared, indicating that the fundamental PM MMF together with all permeance harmonics contribute to the torque production of Vernier machine whereas all PM MMF harmonics but only fundamental permeance in FRPM machine produces the torque. Thanks to the utilized large dc component of air-gap permeance, the torque density of Vernier machine is revealed to be better. Influence of critical parameters on machine performance, such as PM thickness and slot width ratio of the modulation pole, is also investigated. It shows that FRPM machine is more sensitive to the design parameters. Both finite-element analysis and experimental validation are conducted to verify the conclusion.

Wind-induced nonlinear behaviors of twin-box girder bridges with various aerodynamic shapes

Wind-induced nonlinear oscillations of twin-box girder bridges are very sensitive to the aerodynamic shape of the deck (i.e., slot width ratio (SWR) and wind fairing shape) due to the complicated flow characteristics around the bridge deck. This paper presents a fully integrated finite element (FE) model in time domain, involving a nonlinear aerodynamic force model and a bridge FE model, to allow the investigation of nonlinear oscillation behaviors of long-span twin-box girder bridges with various SWRs and wind fairing shapes. The parameters in integrated FE model were firstly identified by using CFD simulation, and then, the proposed model was validated by conducting wind tunnel testing using sectional models and full-bridge aeroelastic models. It demonstrates that the developed integrated model has the capability of simulating the nonlinear flutter behaviors of twin-box girder bridges with various aerodynamic shapes. Furthermore, the prediction results show that the wind fairing shape has significant impact on the degree of freedom participation in coupled oscillation and failure modes, as well as flutter performance of the bridges. In addition, there is an increase in amplitudes of the limit cycle oscillations with the increase in the SWR of the twin-box girder bridges, and the relationships between the bending-torsional coupled oscillation, failure modes, and SWR of the bridges with anti-symmetric wind fairings are opposite to those with symmetric wind fairings.

Comprehensive evaluation of aerodynamic performance of twin-box girder bridges with vertical stabilizers

Although vertical central stabilizer (VCS) on long-span cable-supported bridges is one of practical passive aerodynamic countermeasures, the effectiveness of VCS in improving aerodynamic performance is much dependent on the parameters of VCS. Through a series of wind tunnel tests, in present study we investigated the influences of various combinations of six heights and two positions of VCS on three crucial aerodynamic performances (i.e. stationary aerodynamic performance, flutter performance and vortex-induced vibration (VIV) performance) of a twin-box girder suspension bridge. Results show that for the 20% slot width ratio (SWR) bridge, increasing the height of upward VCS (UVCS) has limited contribution to the improvement in stationary aerodynamic performance owing to the increase of drag force coefficient (CD) and pitching moment coefficient (CM). In addition, the critical flutter wind velocity initially increases with the height increase of VCS, and then significantly decreases after the height of VCS reaches to a certain threshold. Furthermore, the VIV displacement responses significantly become larger after installing higher UVCS and downward VCS (DVCS) from 0.6 h/H to 1.0 h/H, especially for heaving VIV. Most importantly, the implementation of 0.2 h/H DVCS for the 20% SWR twin-box girder bridge could produce the best aerodynamic performance outcomes after comprehensive evaluation.

Flutter characteristics of twin-box girder bridges with vertical central stabilizers

It has been well known that Vertical Central Stabilizers (VCS) have the potential of improving flutter performance of long-span bridges. However, the fundamental flutter mechanisms of VCS are still not fully understood so far. In this study, a series of wind-tunnel tests involving the combination of six representative heights and four types of VCS were conducted to fundamentally investigate the influence of VCS on flutter performance of twin-box girders with various Slot Width Ratios (SWRs). Experimental results show that the flutter instability of 20% SWR is significantly sensitive to the height change of VCS, whereas the VCS have little effect on the flutter performance for 80% and 100% SWR. In addition, the results from Two-Dimensional Three Degree of freedom (2D-3DOF) flutter analysis demonstrates that aerodynamic damping Part A with reference of flutter derivative A2∗ makes the greatest contribution to the flutter instability for a 0.8h/H VCS, while the role of Part D with reference of A1∗H3∗ becomes critical for a short VCS (i.e. the ratio of h/H is less than 0.2). Besides, the results of Computational Fluid Dynamics simulation indicate that the geometry of VCS could potentially influence the transforming vortices’ structures and pressure distribution under the central slotting. Finally, the modified Selberg formula presented in this study has the capability of predicting the critical flutter speeds of twin-box girders with various SWRs and VCS.

Experimental studies on VIV performance and countermeasures for twin-box girder bridges with various slot width ratios

The slot width ratio of a twin-box girder plays an important role in the aerodynamic performance of the corresponding bridge. Therefore, it is necessary to investigate the VIV performance of a twin-box girder with various slot width ratios and evaluate the effectiveness of present VIV countermeasures considering the influence of different slot width ratio. Through a series of wind tunnel tests, the present study firstly investigated the VIV performance of a twin-box girder suspension bridge with six representative slot width ratios ranging from 0% to 100%. Then, four countermeasures, including increasing structural damping ratio, installing grid plates, wind barriers and guide vanes, were checked and comprehensively evaluated with the aim of identifying the most effective VIV control measure. The experimental results showed that the VIV performance of a twin-box girder with 0% slot width ratio (a single box girder) is superior to those with central slot. The maximum normalized heaving VIV amplitude occurs at the slot width ratio of 60% for the 1:60 geometrical scale model (around 0.093) and 80% for the 1:30 scale model (around 0.1), respectively. The significant difference of the torsional VIV responses between the two models with different geometrical scale is found at the slot width ratio of 20%. The comparison of VIV countermeasures for the 20% and 60% slot width ratios suggested that increasing damping ratio is helpful for reducing VIV responses, while installing guide vanes may have adverse effects. The application of grid plates and wind barriers can have positive effects in suppressing the heaving VIV responses, while the effectiveness of grid plates is more obvious with the decrease of grid porosity. Furthermore, the application of the grid plates with 0% grid porosity can perfectly enable the VIV performance of the twin-box girder bridge to meet the requirements of both Sperling indicator and Wind-resistance specification of China.

등가자기회로를 활용한 콜레노이드 타입 선형 액츄에이터 설계 알고리즘 개발

Department of Electrical Engineering, Dong-A University, Busan 49315, Korea(Received 31 March 2016, Received in final form 19 April 2016, Accepted 20 April 2016)This study proposes the design algorithm of an electromagnetic linear actuator with a divided coil excitation system, such as thecolenoid (COL) system, using the equivalent magnetic circuit (EMC) method. Nowadays, the clamping device is used to holdworkpiece in the electrically driven chucking system and is needed to produce a huge clamping force of 40 kN like hydraulic system.The design algorithm for electromagnetic linear actuator can be obtained using the EMC method. At first, the parameter map is used todecide the slot width ratio in the initial design. Next, to make the magnetic flux density uniform at each pole, the pole width isadjusted by the pole width adjusting algorithm with EMC. When the dimensions of the electromagnetic linear actuator are decided, theclamping force is calculated to check the desired clamping force. The design results show that it can be used to hold a workpiecefirmly instead of using a hydraulic cylinder in a chucking system.Keywords: colenoid, electromagnetic linear actuator, equivalent magnetic circuit, electrically driven chucking system

Aerodynamic instability performance of twin box girders for long-span bridges

Twin box girders are a popular choice among long-span bridge engineers, and the aerodynamic performance of such a system is critical to the stability of a bridge under wind excitation. Two groups of twin-box girders with six representative slot width ratios varying from 0% to 100% were utilised to investigate the influence of different wind fairing shapes on aerodynamic instability performance for both torsional divergence and flutter of the girders. The girders with two wind fairing shapes for various slot ratios were investigated by wind tunnel tests and theoretical analyses. Based on the experimental results of static wind loads and critical flutter wind velocities, the symmetry of wind fairing only showed an influence on the development pattern of drag force coefficients and the flutter performance was only significantly affected when the slot width ratio was over 40%. It is also shown that the effect of structural stiffness variation caused by the change of slot width ratio cannot be neglected in stationary torsional divergence analysis. The flutter performance of twin box girders with asymmetric wind fairing is sensitive to slot width ratio due to the existence of optimal slot width, which is opposite to the case with symmetric wind fairing, especially when this ratio is over 40%. Different aerodynamic damping parts contributing to the torsional aerodynamic damping and the participation level of each degree of freedom (DOF) were analysed through a two-dimensional three degree of freedom (2D-3DOF) method, and the results indicate that the improvement in flutter performance can be mainly attributed to the decrease in aerodynamic negative damping Part F (caused by the couple effect of the torsional and vertical motion) and the increase of participation level in heaving motion at the flutter onset. Particle Image Velocimetry (PIV) techniques were further employed to reveal that the change in central slot width ratio and the symmetry of wind fairing have a great influence on the vortices’ characteristics, especially in the central slot region when the slot ratio is over 40%. This was determined by observing the flow structures around the deck sections in terms of wind velocity field and vortex characteristics.

Contribution of experimental fluid mechanics to the design of vertical slot fish passes

This paper presents the main results of an experimental study of mean and turbulent characteristics of flow in a scale model of a vertical slot fish pass with varying width and slope (from 5% to 15%). Experimental hydraulic modelling was combined with the study of fish behaviour in the model. The discharge coefficient, which significantly affects the design of such facilities, varied from 0.67 to 0.89 and was strongly influenced by the slope. Two distinct flow patterns were observed, depending on the slope and the fish pass width. The point of transition between the two states was determined. Low velocity areas are likely resting zones for fish and particular attention was paid to evaluating these areas. Slope was found to affect both the volume of the low velocity zone, and the value of turbulent kinetic energy in these areas. The statistical characteristics of turbulent kinetic energy in the pools were linked primarily to the maximum velocity in the jet. An analysis of the behaviour of juvenile brown trout (Salmo trutta ) in the scale model clearly showed that the fish avoided the areas of high velocities in the jet, except at the slot itself where they took advantage of the jet’s non-stationary character. Low-velocity areas were not frequented uniformly by fish, which stayed most frequently in the zone located just downstream from the slot and behind the small side baffle. It is suggested that future studies might investigate lower pool-length to slot-width ratios, which might make it possible to increase the slope significantly and should also examine ways of improving hydraulic conditions for fish by carefully distributing obstacles in pools.

Numerical model for flow past a slot in a rectangular conduit

The three-dimensional two-equation k–ω turbulence model is applied to obtain the characteristics of flow past a rectangular floor slot located in a rectangular closed conduit. The predictions of the numerical simulation are validated using existing experimental data. The model faithfully reproduces the flow behavior including flow separation in the expanding flow region downstream of the slot. In particular, the model predictions agree well with the experimental data related to pressure and velocity fields. As such, following proper model validation, the numerical model can yield design data pertaining to flow characteristics for different discharge ratios and slot width ratios for many other slot flow situations encountered in engineering practice.

A study of slot-entry hydrostatic/hybrid journal bearing using the finite element method

A theoretical study concerning the static and dynamic performance of hydrostatic/hybrid journal bearing compensated by slot restrictor has been presented using the finite element method (FEM). Results have been presented for a double row symmetric as well as asymmetric configurations for different values of slot width ratios (SWR) and external load ( W ̄ 0 ). In order to have a better understanding of their performance vis-à-vis other non-recessed bearing configurations, the performance characteristics of slot-entry journal bearings have been compared with that of similar hole-entry compensated journal bearings using capillary, orifice and constant flow valve restrictors for the same bearing geometric and operating parameters. The comparative study indicates that asymmetric slot-entry journal bearings provide an improved stability threshold speed margin compared with asymmetric hole entry journal bearings compensated by capillary, orifice and constant flow valve restrictors.