Decrease In Maximum Pressure Research Articles

Effect of varnish on the performance and stability of journal bearings

This paper is dedicated to characterizing the steady-state and dynamic behavior of journal bearings with the provision for varnishing. Degraded base oils and additives cause varnish at high temperatures. Once the varnishing initiates, the oil flow is restricted due to the reduction in film thickness, which leads to an increase in the operating temperature and further accelerated varnishing. The effect of the varnish on the bearing performances is predicted by solving the Reynolds equation for the pressure distributions with the mass conservation algorithm coupled with the energy equation through the viscosity. The solution of the Reynolds equation with the perturbations of the displacement and the velocity is used to calculate the stiffness and damping coefficients and determine the dynamic behavior of the bearing. At a given eccentricity ratio, the maximum pressure and temperature with the varnish become considerably higher than those without the varnish due to the reduced film thickness. Results are presented for both single and double axially grooved journal bearings. Results show that the maximum pressure decreases when the varnish size extends circumferentially at a given varnish thickness, but the maximum temperature still remains relatively constant. For both single and double-grooved bearings, the critical speed decreases considerably, leading to the reduction of the stability of the system.

Numerical simulation of in-vessel steam explosion for China third-generation PWR

In this study, in order to evaluate the Reactor Pressure Vessel (RPV) integrity under in-vessel steam explosion loads for China third-generation Pressurized Water Reactor (PWR), 2D and 3D numerical simulation of in-vessel steam explosion is conducted using MC3D code. The sensitivity analyses for in-vessel steam explosion are performed, including break area, water temperature, water level, melt temperature, and break height. The results show that the premixing stage cannot cause RPV failure and the possibility of the steam explosion blowing the RPV upper head off is almost non-existent. When the break area increases, the maximum pressure and impulse of the RPV inner wall increase obviously first and then generally decrease slightly. With the increase of water temperature, the maximum pressure and impulse first increase and then decrease. When the water level is higher, the maximum pressure variation is small. When the water level is very low, the maximum pressure decreases. The maximum impulse generally decreases with the decrease of the water level. When the melt temperature exceeds 2850 K, the steam explosion is not sensitive to the melt temperature. With the increase of the break height, the maximum pressure and maximum impulse first increase and then decrease. Furthermore, based on the results of sensitivity analysis, two cases of conservative conditions are selected, and the RPV integrity under in-vessel steam explosion loads for China third-generation PWR is considered. The result shows that the integrity of the RPV can be maintained under the in-vessel steam explosion loads for China third-generation PWR with a large margin. These studies provide some reference to improve the severe accident management strategy in China.

The Influence of General and Local Muscle Fatigue on Kinematics and Plantar Pressure Distribution during Running: A Systematic Review and Meta-Analysis.

Fatigue has the potential to alter how impact forces are absorbed during running, heightening the risk of injury. Conflicting findings exist regarding alterations in both kinematics and plantar pressure. Thus, this systematic review and subsequent meta-analysis were conducted to investigate the impact of general and localized muscle fatigue on kinematics and plantar pressure distribution during running. Initial searches were executed on 30 November 2021 and updated on 29 April 2023, encompassing PubMed, The Cochrane Library, SPORTDiscus, and Web of Science without imposing any restrictions on publication dates or employing additional filters. Our PECOS criteria included cross-sectional studies on healthy adults during their treadmill running to mainly evaluate local muscle fatigue, plantar pressure distribution, biomechanics of running (kinematics, kinetics, and EMG results), and temporospatial parameters. The literature search identified 6626 records, with 4626 studies removed for titles and abstract screening. Two hundred and one articles were selected for full-text screening, and 20 studies were included in qualitative data synthesis. The pooled analysis showed a non-significant decrease in maximum pressure under the right forefoot's metatarsus, which was more than the left rearfoot after local muscle fatigue at a velocity of 15 km/h (p-values = 0.48 and 0.62). The results were homogeneous and showed that local muscle fatigue did not significantly affect the right forefoot's stride frequency and length (p-values = 0.75 and 0.38). Strength training for the foot muscles, mainly focusing on the dorsiflexors, is recommended to prevent running-related injuries. Utilizing a standardized knee and ankle joint muscle fatigue assessment protocol is advised. Future experiments should focus on various shoes for running and varying foot strike patterns for injury prevention.

Influence of the injection molding thermal boundary conditions on the filling flow of PET

During the filling phase of the injection molding process, the polymer in contact with the wall solidifies, developing the so-called skin layer. Although the no-flow temperature is often exploited in numerical simulations to model the skin layer formation mechanism, there is still an incomplete understanding of what happens for semi-crystalline PET. In fact, for this polymer, the high shear stresses near the cavity wall combined with the thermal gradient at the polymer-mold interface can cause the so-called flow-induced crystallization. This work aims to experimentally investigate the skin layer formation at different injection molding processing conditions. A full-factorial experimental plan was performed using a commercial PET injected into an open-cavity mold. The thermal and mechanical boundary conditions at the polymer-wall interface were varied using insulating coatings and different flow rates, respectively. The mold coatings were applied to different steel substrates to consider the substrate thermal conductivity contribution. Different flow rates were imposed, varying the cavity thickness and the injection speed. The in-line acquisition of the cavity pressure allows for assessing the contributions of the modified boundary conditions to the solidified skin layer formation. The results show that the insulating mold coating changes the thermal boundary conditions, leading to a maximum pressure decrease of 14 %. The cavity pressure vs. filling time curves for the uncoated inserts show an evident derivative discontinuity, suggesting the onset of flow-induced crystallization.

In-situ measurements of energetic depth-limited wave loading

An extensive database of in situ measurements of wave impact pressure on the wall of a composite breakwater and associated explanatory variables (i.e., waves, wind, and water level) was collected in a particularly high-energy wave environment. Due to the bottom profile, which includes a wide mound of concrete blocks with a seaward edge that rises to the Lowest Astronomical Tide level over a large distance, most waves break before reaching the monitored barrier, making the data set representative of depth-limited wave loading. Maximum pressure is consistently found at the sensor position closest to the mean free surface, and statistically, a decrease of maximum pressure with the altitude is observed. Nevertheless, the database also shows a wide variety of vertical profiles of maximum pressure. A detailed analysis of the pressure signal shows that there are two impact classes associated with large pressure values. The first is mostly observed during stormy conditions with relatively slow pressure variations over time and a fairly uniform spatial distribution. The second class exhibits very limited pressure peaks in time and space and is most often observed during moderate sea states and high water levels. The pressure signals for each class agree well with the prediction of the PROVERB impact classification based on breakwater dimensions, water level, and wave parameters. Our dataset also shows the existence of impacts with simultaneous large pressure and rise time, which extends the range of the observed values of the pressure impulse already reported in-situ from 31000 Pa.s to 100000 Pa.s. For strong impacts that show regular upward propagation, the peak pressure propagation velocity was estimated and most values remain below 20 m/s. Finally, we performed a statistical analysis to relate the maximum pressure to a number of variables, including offshore wave parameters, water level, and wind parameters. The multiple linear regression model created confirms the dominant influence of wave height and the negligible influence of the wind on pressure maxima. The other wave parameters are still significant but of secondary importance. Finally, the upper bound of the 99% prediction interval predicts the maximum pressure given a set of wave and water level conditions with a good confidence level which is an encouraging result.

Effect of vent area, vent location and number of vents on vented hydrogen deflagrations in a 27 m3 chamber

Experiments in a 27 m3 chamber are performed to investigate the effect of vent parameters on the pressure development during homogenous or non-homogenous vented deflagrations, and the performance of Molkov’ models for predicting maximum overpressures is also evaluated. The results show that maximum overpressures exhibit monotonic behaviour as hydrogen concentration increases from 16% to 20.2%. Larger vent area leads to a smaller maximum overpressure, but the rate of maximum pressure decrease with the increase of the vent area is lower as the vent area increases. The vent location and number of vents have a less effect on overpressures during homogenous deflagrations, but the effect becomes more pronounced for non-homogenous deflagrations. Furthermore, two pressure peaks caused by the external explosion appear in the case of two vents. Molkov’ best-fit model over-predicts maximum overpressures for vent area of 1.76 m2, and under-predicts maximum overpressures for vent area of 3.14 m2 located on the roof, but the use of conservative model can give conservative predictions for all tests.

Simulation of Air Puff Tonometry Test Using Arbitrary Lagrangian-Eulerian (ALE) Deforming Mesh for Corneal Material Characterisation.

Purpose: To improve numerical simulation of the non-contact tonometry test by using arbitrary Lagrangian-Eulerian deforming mesh in the coupling between computational fluid dynamics model of an air jet and finite element model of the human eye. Methods: Computational fluid dynamics model simulated impingement of the air puff and employed Spallart–Allmaras model to capture turbulence of the air jet. The time span of the jet was 30 ms and maximum Reynolds number was, with jet orifice diameter 2.4 mm and impinging distance 11 mm. The model of the human eye was analysed using finite element method with regional hyperelastic material variation and corneal patient-specific topography starting from stress-free configuration. The cornea was free to deform as a response to the air puff using an adaptive deforming mesh at every time step of the solution. Aqueous and vitreous humours were simulated as a fluid cavity filled with incompressible fluid with a density of 1000 kg/m3. Results: Using the adaptive deforming mesh in numerical simulation of the air puff test improved the traditional understanding of how pressure distribution on cornea changes with time of the test. There was a mean decrease in maximum pressure (at corneal apex) of 6.29 ± 2.2% and a development of negative pressure on a peripheral corneal region 2–4 mm away from cornea centre. Conclusions: The study presented an improvement of numerical simulation of the air puff test, which will lead to more accurate intraocular pressure (IOP) and corneal material behaviour estimation. The parametric study showed that pressure of the air puff is different from one model to another, value-wise and distribution-wise, based on cornea biomechanical parameters.

Geometrical analysis of elliptical journal bearings and its effects on friction and load capacity

Elliptical bearings are one type of non-circular journal bearings which has two main advantages over the conventional circular bearings: lower temperature rise and lower vibrations. In this study, the energy equation and Reynolds equation are simultaneously solved under adiabatic boundary conditions. The predicted pressure and temperature are compared to the results of published literature for verification purposes. A parametric study is then conducted on the effect of geometrical parameters of the elliptical journal bearing on the load capacity, friction force, pressure, and oil temperature. Effect of geometric parameters of the bearing on the performance is studied. The results show that non-circularity parameter is the most influential parameter in the bearing, and an increase in the non-circularity results in the decrease in maximum pressure and temperature as well as the friction force. Increasing the eccentricity ratio, on the other hand, will cause an increase in the pressure, temperature, and the friction force. Changes in the angle between the major axis of the bearing and load direction decrease the load-carrying capacity and the non-dimensional pressure and results in an increase in the friction coefficient.

The composition determination of combustion products of modified ethanol

The content of pyrolysis products during combustion of modified ethanol in the Rapid Compression Machine (RCM) was studied. It was found that significant reduction in the ignition delay time for lean reactive mixture (φ = 0.6) with a decrease in maximum pressure and unchanged mean rate of pressure. It indicates an increase in the burning rate of the mixture. It has been observed that the modification of ethanol with carbon nanoparticles leads to decrease in the content of methane and hydrogen in combustion products, but ignition delay time does not change (A1) or reduce by 35% (A2) at φ = 1.

Performance and combustion characteristics of a compression ignition engine running on diesel-biodiesel-ethanol (DBE) blends – Potential as diesel fuel substitute on an Euro III engine

Experimental tests on an Euro III compression ignition engine were performed with blends of diesel B15 fuel with ethanol (0–20 vol%) and 1 vol% of an original additive, defined as a mixture of 72.5 vol% of castor oil, 17.5 vol% of soybean biodiesel and 10 vol% of n-butanol. Such mixtures were compared to commercial diesel B7 E0 fuel. The results showed that the addition of ethanol implied an increase of the ignition delay, a faster heat release and a decrease of maximum pressure. Without any optimization of injection timing and combustion, results showed a better conversion of ethanol chemical energy into brake power, when compared with a commercial flex fuel spark ignition engine. In addition, a small increase in the indicated efficiency, in particular at low loads (25% of the maximum torque obtained with commercial fuel under the same rotation), was also observed. Specific fuel consumption increased almost 2% for each 5 vol% of anhydrous ethanol in the blends since the density and the lower heating value of the fuel decreased. A significant decrease of maximum torque was also observed, due to a reduction of the injected volume of fuel (up to 30% in diesel B15 E20 fuel).

Study on effects of particle size and maximum pressure drop on the filtration and pulse-jet cleaning performance of pleated cartridge filter

In recent years, pleated cartridge filters have been widely used in the process of industrial production. However, most of the existing studies are focused on the structure optimization design of filters, and there are few studies on the effects of two important factors, namely, particle size and maximum pressure drop, on the performance of filters. So, in this study, the effects of two factors on the filtration and pulse-jet cleaning performance of pleated cartridge filter were investigated through experiments. For the same maximum pressure drop, both average and average residual pressure drops are reduced with the rise of particle size, and meanwhile both the number of pulse-jet cleaning and the average dust emission concentration decrease, which improves the dust collection efficiency. For the same particle size, both average and average residual pressure drops are reduced with the decrease of maximum pressure, but both the number of pulse-jet cleaning and the average dust emission concentration are increased, which lowers the dust collection efficiency.

Multiphase flow analysis of hydrodynamic journal bearing using CFD coupled Fluid Structure Interaction considering cavitation

In this study, a fully three-dimensional CFD analysis and multi-phase flow phenomena, has been successfully implemented for simulation of hydrodynamic journal bearing considering the realistic deformations of the bearing with Fluid Structure Interactions (FSI) along with cavitation. Mixture model is used to model cavitation in the bearing and parametric modelling is used for modifying the flow domain due to deformation. Both systems are coupled and design optimization based on multi objective genetic algorithm (MOGA), is used to obtain optimized solution of the attitude angle and eccentricity for the combination of operating speed and load. In the study of bearings with and without effects of cavitation, it is observed that maximum pressure values drop when cavitation is considered in the bearing. Also there is decrease in maximum pressure when elastic deformation in the bearing is considered. The oil vapour distribution goes on increasing with the increase in shaft speed, thus lowering the magnitude of the pressure build up in the bearing. Multiphase study of bearings with cavitation hence becomes extremely important in case of bearings operating with higher speeds. The experimental data obtained showed very good agreements with numerical results and considerable reduction in computation time is observed.

A biomechanical research of foot pressure for lower extremity in gait wearing trail walking shoes

The aim of this study is to analyze foot pressure distribution of trail walking shoes while walking. Hiking, a recreational activity which is able to exercise whole body in the nature without any cost, has compositive effects which can reduce stress, strengthen muscles of entire body and improve cardiopulmonary function [1]. The Topography is hard near the surface and has rough characteristic because of rocks. These condition can lead to injuries to feet in hiking and aggravating fatigability of foot when people hike for a long time [2],so hiking boots which are specially functioned are encouraged because walking on the rough surface has latent dangerousness of injury [3]. Trail walking shoes generally provide more stability and support than regular walking shoes. Trail walking shoes are for natural trails. In rocky, rooted, dusty and muddy trails, a trail walking shoe gives added traction and support. Ten healthy males participated in this study. All subjects were free of lower extremity pain, history of serious injuries or operative treatment or subjective symptoms interfering with walking. Each subject wore four different shoe types during walking trials on a treadmill at a constant speed of 4.2km/hour. Pressure distribution data (contact area, maximum force, peak pressure, maximum mean pressure) were collected with pressure device at a sampling rate of 100Hz. Shoes used in the experiment are which developed in four shoes. Developed trail walking shoes (Type A), first developed trail walking shoes (Type B) and other company’s trail walking shoes (Type C, Type D) are selected for the experiment. Tested about ‘Comparison in Lightweightedness’ among the shoes (Figure ​(Figure1).1). ‘Comparison in Lightweightedness’s result is Type A (324.92 g) < Type B (350.70 g) < Type C (374.67 g) < Type D (397.16 g). Figure 1 Type A: developed trail walking shoes, Type B: first developed trail walking shoes, Type C, D: other company’s trail wxalking shoes Table 1 Result of Foot Pressure Contact area of functional shoes (Type A) increased in comparison to general shoes (Type C, Type D). At the same time, foot pressure decreased in comparison to general shoes (Type C, Type D). It is expected that Type A Functional shoes give more comfort and fit by increasing the contact area and decreasing peak pressure. In the result of the analysis of plantar pressure, Type A reported higher than other shoes on the forefoot. At the maximum force, Type A is observed as the smallest maximum force in almost part. These results, which is similar to Park (2009)’s research [3], decreased the confining pressure which can lead the deformation of forefoot’s toe. In the maximum pressure result, the outcome is similar to maximum force, which the smallest is Type A < Type D < Type B < Type C. This can decline the impulse which occurs in heel strike section, as a result, this can decrease the fatigability of foot in long-time walking. In addition, similar to Oh and Lee (2009)’s research [4], it can lighten the impulse force delivered to the body, as being the important factor which can decrease the weight to the leg joint. As examining the result of the average pressure, Type A < Type C < Type D < Type B is observed. In this thesis, we analyzed the contact area of plantar pressure, maximum force, maximum pressure, average pressure. Through this result, we can know impact force alleviation for foot and physical fatigue, too. When considering the pressure change of the foot, Type A’s contact area of foot is wider than the others. So, its wearing feeling will be better than the others. In case of maximum pressure, it is lower than the others and mid foot, hind foot’s result is similar. So, we expect ‘shockproof and to disperse pressure’ will be good. Also, with foot and shoe contact area’s increase, there may be amaximum force and maximum pressure decrease. So, it can decrease the foot’s and pelvic limb’s fatigue. We offer the data of the dispersing pressure functionality of walking hiking shoes, so it can be of help to a product’s functionality improvement.

Validation of a lameness model in sows using physiological and mechanical measurements1

The objective of this study was to develop a validated, transient, chemically induced lameness model in sows using subjective and objective lameness detection tools. Experiment 1 determined an effective joint injection technique based on volume and placement of dye using feet collected from 9 finisher pigs and 10 multiparity cull sow carcasses. Experiment 2 confirmed the injection technique in live animals and produced a transient clinical lameness in 4 anesthetized sows injected with amphotericin B (15 mg/mL) in the distal interphalangeal joints of the claw. Clinical lameness was assessed by a categorical lameness scoring system, and a postmortem visual confirmation of joint injection technique was obtained. In Exp. 3, 6 sows were injected with 0, 10, or 15 mg/mL amphotericin B in either the left or right hind foot and were monitored until clinical resolution. Treated sows demonstrated elevated clinical lameness scores. These changes resolved by 7 d after lameness induction. Control sows injected with sterile saline developed a clinical lameness score of 0.5, which resolved 72 h post injection. In Exp. 4, 36 sows were injected with 10 mg/mL amphotericin B in 1 of 4 injection sites (left front claws, right front claws, left rear claws, and right rear claws). All injected sows exhibited a decrease in maximum pressure, stance time, and number of sensors activated on the GaitFour (P < 0.05) sensor system. A static force plate also demonstrated a decrease in weight (kg) being placed on the injected foot when all feet were injected (P ≤ 0.05). Injection of amphotericin B induced a predictable acute lameness that resolved spontaneously and is an effective method to model lameness in sows.

An investigation of the optimal load paths for the hydroforming of T-shaped tubes

This paper proposes a new method to design the optimal load curves for hydroforming T-shaped tubular parts. In order to assess the mathematical models, a combination of design of experiment and finite element simulation was used. The optimum set of loading variables was obtained by embedding the mathematical models for tube formability indicators into a simulated annealing algorithm. The adequacy of the optimum results was evaluated by genetic algorithm. Using this method, the effect of all loading paths was considered in hydroforming of T-shaped tubes. Eliminating of variables with lower effect could simplify the problem and help designers to study the effect of other parameters such as geometrical conditions and loading parameters. Applying the optimal load paths obtained with the proposed method caused an improvement in the thickness distribution in the part as well as a decrease in maximum pressure.

Knee model of hydrodynamic lubrication during the gait cycle and the influence of prosthetic joint conformity

Background.The influence of the total joint components’ elastic deformation on lubrication is generally accepted, but little is known about the influence of joint conformity under hydrodynamic lubrication based on fluid film interposition. The aim of this study was to evaluate induced pressure and stresses in the knee under fluid film lubrication during the stance phase of walking under various joint conformity conditions. Methods.A theoretical two-dimensional (2D) geometric model of knee prosthesis contact, with Dirichlet boundary conditions at both edges, and with a conformity index (CI) of 0, 0.3, 0.5, 0.6, 0.7, 0.8, 0.9, 0.92, 0.94, 0.96, 0.98, 0.99, 0.995, and 1.0, was used to calculate the spatiotemporal lubricant flow on a synovial fluid rheological model. With the instantaneous load as a source term, the Reynolds lubrication equation was subsequently solved following a finite volume approach in two dimensions and three dimensions. Results.Conformity strongly influenced the peak pressure, from 47 MPa with CI = 0 to 1.4 MPa with CI = 1, with a definite behavior change from CI = 0.96. The role of hydrodynamic lubrication was restricted to early steps of the stance phase. With CI < 0.96, there was a smooth maximum pressure decrease with increasing CI. In contrast, the maximum pressure fell abruptly with conformity > 0.96. Conclusion.The present model suggested the limited modifying effect of hydrodynamic lubrication in total knee replacement systems. However, its role during the early stance phase, coupled with high conformity, helps significantly to decrease compressive stresses on the polyethylene, fostering the beneficial effect of high conformity in a mixed lubrication regime. This beneficial effect may also be of great interest in total knee replacement systems based on materials with less deformation.

Analysis of Rarefied Effects of a Nano-scale Magnetic Head/Disk

When the decrease in the space between magnetic head and disk arrived at 10 nm or less, which is much lower than the mean free path of gas molecules, the gas flow presents distinctive features against the macro features because of the rarefied effects. The modified Reynolds equation considering rarefied gas effect is used to calculate the rarefied region of a negative pressure magnetic head working in the distance of 10 nm. Inverse Knudsen number was adopted to calculating the ratio of the rarefied area. According to the numerical results, discussions and analyses are then presented to reveal the rarefied effect on the working performances of a magnetic head. The results show that the magnetic head works in the slip-flow and transition regions and moves to the transition region with the increase in velocity. Furthermore, the maximum rarefied effects occur at the side edges where the flying height is thinner and pressure is lower, rather than in the minimum flying height on the rear. The results also show that with considering the rarefied effects, the load-carrying capacity of the magnetic head and the maximum pressure decrease significantly, but the minimum pressure slightly changes.

Six-Year Follow-Up of Botulinum Toxin A Intradetrusorial Injections in Patients with Refractory Neurogenic Detrusor Overactivity: Clinical and Urodynamic Results

BackgroundMost reports in the literature on botulinum toxin A (BoNTA) therapy for neurogenic detrusor overactivity (NDO) are based on the results of a single injection. Because most patients may require retreatment, the efficacy and safety of multiple injections must be addressed clearly. ObjectiveTo investigate the effectiveness and safety of BoNTA intradetrusorial injections in a group of spinal cord–injured (SCI) patients with refractory detrusor overactivity (DO). Design, setting, and participantsSeventeen SCI patients were prospectively included in the study and followed up to 6 yr. InterventionAll patients received repeat intradetrusorial injections of BoNTA 300 units (Botox, Allergan, Irvine, CA) under cystoscopic control on an inpatient basis. MeasurementsThe preliminary assessment included voiding diary, urodynamics, kidney and bladder ultrasound, and cystourethrography. Patients also completed a standardised quality-of-life (QoL) questionnaire. Clinical evaluation, urodynamics, urinary tract imaging, and QoL assessment were repeated every year throughout the follow-up. Results and limitationsBefore treatment, all patients complained of urinary incontinence and had DO. Bilateral and monolateral renal pelvis dilatation were detected in six and five patients, respectively, and a monolateral and third-grade vesicoureteral reflux was observed in three. At 6-yr follow-up, a significant decrease in the frequency of daily incontinence episodes (p<0.01), a significant increase in first uninhibited detrusor contraction and in maximum bladder capacity (p<0.001 for both), and a significant decrease in maximum pressure of these contractions (p<0.01) were observed. Fifteen patients (88.2%) were completely continent. Renal pelvis dilatation and vesicoureteral reflux resolved in all cases, and the QoL index significantly increased. Limitations of the study are related to the small number of included patients. ConclusionsIn SCI patients with refractory NDO who do not want or are unfit for invasive reconstructive surgery, BoNTA intravesical treatment represents a valid alternative to control DO and urinary incontinence and to preserve upper urinary tract function over a long-term follow-up.

SIX YEARS FOLLOW UP OF BOTULINUM A TOXIN INTRADETRUSORIAL INJECTIONS IN PATIENTS WITH REFRACTORY NEUROGENIC DETRUSOR OVERACTIVITY: CLINICAL AND URODYNAMIC RESULTS

Background: Most reports in the literature on botulinum toxin A (BoNTA) therapy for neurogenic detrusor overactivity (NDO) are based on the results of a single injection. Because most patients may require retreatment, the efficacy and safety of multiple injections must be addressed clearly. Objective: To investigate the effectiveness and safety of BoNTA intradetrusorial injections in a group of spinal cord–injured (SCI) patients with refractory detrusor overactivity (DO). Design, setting, and participants: Seventeen SCI patients were prospectively included in the study and followed up to 6 yr. Intervention: All patients received repeat intradetrusorial injections of BoNTA 300 units (Botox, Allergan, Irvine, CA) under cystoscopic control on an inpatient basis. Measurements: The preliminary assessment included voiding diary, urodynamics, kidney and bladder ultrasound, and cystourethrography. Patients also completed a standardised quality-of-life (QoL) questionnaire. Clinical evaluation, urodynamics, urinary tract imaging, and QoL assessment were repeated every year throughout the follow-up. Results and limitations: Before treatment, all patients complained of urinary incontinence and had DO. Bilateral and monolateral renal pelvis dilatation were detected in six and five patients, respectively, and a monolateral and third-grade vesicoureteral reflux was observed in three. At 6-yr follow-up, a significant decrease in the frequency of daily incontinence episodes (p < 0.01), a significant increase in first uninhibited detrusor contraction and in maximum bladder capacity (p < 0.001 for both), and a significant decrease in maximum pressure of these contractions (p < 0.01) were observed. Fifteen patients (88.2%) were completely continent. Renal pelvis dilatation and vesicoureteral reflux resolved in all cases, and the QoL index significantly increased. Limitations of the study are related to the small number of included patients. Conclusions: In SCI patients with refractory NDO who do not want or are unfit for invasive reconstructive surgery, BoNTA intravesical treatment represents a valid alternative to control DO and urinary incontinence and to preserve upper urinary tract function over a long-term follow-up. # 2008 Published by Elsevier B.V. on behalf of European Association of Urology.

Journal bearings optimization for mass balancing systems used in internal combustion engines

PurposeTo provide an optimization methodology for the journal bearings of mass balancing systems, that consists in a sensibility analysis of the journal bearings design parameters in the journal bearing operating parameters, as well as the comparison and selection of the journal bearing materials and the selection of the lubrication grooves suitable.Design/methodology/approachThe methodology followed comprehends three steps. The first step is the one by one variation of the journal bearing design parameters (radial clearance, journal bearing diameter and journal bearing length) to analyse, independently, their influence on the journal bearing operating parameters (minimum film thickness, maximum pressure and power loss). The second step is the analysis and comparison of the metallic materials that can be used in the journal bearings. The third step is the selection of the lubrication groove.FindingsApplying this methodology it is shown that increasing the radial clearance the minimum film thickness increases and the maximum pressure and the power loss decrease, increasing the journal bearing length the minimum film thickness and the power loss increase and the maximum pressure decreases, at last, increasing the journal bearing diameter the minimum film thickness, the maximum pressure and the power loss increase. The materials that should be used are the white metals (Babbitts). And the journal bearing lubrication grooves should be circumferential.Practical implicationsThis method gives the user the possibility to eliminate potential failures of the journal bearings, or simply to make a sensibility study of the influence of the journal bearing design parameters in the operating ones.Originality/valueThis paper provides a simple and objective methodology to make a sensibility analysis of the influence of the journal bearing design parameters in the operating parameters, as well as select the journal bearing materials and lubrication grooves.