Diaphragm Length Research Articles

Seismic Performance of Wall-Type Concrete-Filled Steel Tubular Column to H-Beam Connections with Internal Diaphragms

This study introduces a new internal diaphragm joint to connect steel beams with wall-type concrete-filled steel tubular (WCFST) columns. This study combines experimental research with numerical simulations for analysis. Firstly, one full-scale test specimen was designed and subjected to cyclic loading. The obtained failure mode and hysteresis curves illustrate that the joint specimens exhibit ample energy dissipation capacities. Subsequently, a reliable FE model was obtained based on experimental verification, and parametric analysis was conducted. The findings indicate that axial compression ratios critically affect the load-carrying capacity and displacement at failure, with a 2% reduction in capacity for each 0.1 increment in the ratio. The thicknesses of the column web and flange in the joint area are recommended to be 0.85 to 1.2 times and 1 to 1.2 times the beam flange thickness, respectively. The length of the internal diaphragm is advised to be between 0.2 and 0.3 times the width of the cross-section. Overall, these results significantly enrich our understanding of WCFST systems and will inform future design and construction best practices.

Study on Air Cabin Ventilation System by Local Structural Optimization during Tunnel Construction

In tunnel construction, the difficulty of ventilation gradually increases with the increase of ventilation distance, which endangers construction safety and delays construction progress. This paper presents an air cabin ventilation system of the tunnel during construction. Theoretical calculations show that the energy consumption of this ventilation system is reduced by 20.7% compared with blowing ventilation, especially since the resistance loss along the air duct is reduced by 47.04%. A 3D numerical model validated with field test data was employed to discuss the air cabin structural parameters on the ventilation efficiency of the axial fan. The results show that the relative pressure on the fan’s end face increases when the air cabin’s length–width ratio is R = 1:2. The fan spacing S = 2–4 m can ensure the larger relative pressure of multiple fans. The significant difference in air demand between the left and right sides causes the disordered airflow. Set a middle diaphragm length of 1.5 D in the air cabin, which can effectively reduce the phenomenon. The middle diaphragm with a radian of 30°effectively reduced the local loss by 59.40%. The proposed ventilation system shortens the ventilation distance and has the advantages of low energy consumption and resistance loss. It improves the construction environment and is a valuable means of ventilation design for tunnel construction.

Back Analysis of Surrounding Rock Parameters of Large-Span Arch Cover Station Based on GP-DE Algorithm

Due to the characteristics of soil–rock composites and large-span arches, the surrounding rock parameters of stations are difficult to obtain accurately under soft upper and hard lower geological conditions when the arch cover method is used to carry out the construction of a large-span underground excavation station. To optimize the design of stations and guide the next step of construction, an intelligent inverse analysis method, the Gaussian process differential evolution co-optimization algorithm (GP-DE algorithm), is proposed for the arch cover method for station construction. Taking the Shikui Road station of the Dalian Metro Line Five as the engineering background, the finite element model of FLAC3D is established. By combining the measured data of the sensor and the monitoring data obtained using the orthogonal scheme, this algorithm is used for the joint back analysis of displacement stress and the accuracy of the inversion parameters is verified by forwarding the calculation for FLAC3D. By using the obtained surrounding rock parameters, the demolition length of the center diaphragm to the Shikui Road station is optimized. Under different numbers of training samples, the inversion effect of the GP-DE algorithm and the other three common back-analysis algorithms is compared and analyzed. Finally, based on the iteration rate and convergence effect, the value range of the differential evolution algorithm parameters F and CR is given. The results show that the forward calculation results of the parameters obtained from the back analysis are in good agreement with the actual values, and the accuracy of the back-analysis results is high.

T‐Joint Micromixer Coupled with Deforming Diaphragm

A novel active micromixer design involving an oscillating diaphragm is proposed. A simulation study is performed to determine the effect of diaphragm length, amplitude, and frequency of the oscillating diaphragm on the mixing index. The geometry is a simple T-joint with an elongated channel for the outlet with a diaphragm on the outlet channel wall. The fluids at the inlets are similar in fluid properties with the same flow rate and diffusion constant. The mixing index saturates with increasing frequency and amplitude of oscillation for a given diaphragm length. The diaphragm's effectiveness was calculated based on the pressure difference between the diaphragm inlet and outlet zone. The effectiveness declined with an increase in the frequency of the diaphragm oscillation. An analytical expression is derived to find the effect of the frequency and amplitude of the diaphragm oscillation on the mixing index. This simple novel design may find wide applications in various industrial fields.

Optimization of nanofluid heat transfer in a microchannel heat sink with multiple synthetic jets based on CFD-DPM and MLA

This study uses a combination of computational fluid dynamics consisting of the discrete phase model (CFD-DPM) coupled with support vector regression-particle swarm optimization (SVR-PSO) techniques to maximize the cooling performance of Al2O3water nanofluids in a microchannel heat sink (MCHS) with multiple synthetic jets (SJs). First, a CFD parametric study is carried out to understand the effect of influential parameters, including orifice spacing, particle volume fraction, orifice height, diaphragm length, phase actuation of jets, frequency and amplitude of oscillating diaphragms. A hybrid SVR-PSO algorithm is then adopted to predict the optimum values of the influential parameters for the maximum homogeneous heat transfer. The results predicted by the machine learning algorithm (MLA) are also compared to CFD findings. 0.15% and 3.5% deviations are found between predicted and actual values for the minimum average temperature and temperature uniformity, respectively. The parametric study reveals that heat transfer increases when the two jets are placed apart from each other. Based on the parametric study, the average temperature drops by 4.3 K as the membrane length increases from 0.95 mm to 1.96 mm. The highest heat transfer is obtained at a particle volume fraction of 5% in both jet arrangements. It is found that increasing the amplitude and frequency of the membranes results in better cooling performance. The results also confirm that larger orifice heights allow the creation of longer and stronger flows in the orifices that propagate the furthest in the microchannel. Overall, in-phase jet configurations show more uniform and lower temperatures (e.g., better heat transfer) at higher particle concentrations compared to the 180° out-of-phase jet arrangements.

FCS technology: A novel electrodynamic transducer architecture

For a century now, acoustic electrodynamic transducers have been bound by axisymmetric motor structures for high performance due to the assumption in transducer theory that the diaphragm moves pistonically for all operating frequencies. This is of course a flawed assumption, and results in much research and development being focused on the vibro-acoustic components of the driver to minimize cone breakup at higher frequencies.A new architecture for the electrodynamic motor has been developed which helps to address this inherent problem. Flat Core Speaker (FCS) technology presents an architecture that is a rearrangement of the conventional electrodynamic motor structure with a planar voice coil and bobbin assembly that is situated between two parallel bar magnets. This results in a high aspect ratio design where the bobbin runs along the length of a flat diaphragm, leading to even force distribution, and therefore pistonic movement, while utilizing a thin profile with a flat diaphragm. COMSOL simulations and Klippel measurement data support these claims and show evidence of FCS technology having comparable performance to conventional drivers in a slimmer profile and blowing conventional high aspect ratio driver performance out of the water.

REMOVAL OF SIDE ILLUMINATION IN THE IMAGE PLANE IN TWO-MIRROR PANCRATYC SYSTEM FOR COLLIMATOR

The specifics of certain tasks, which are solved by a collimator, as well as the large amounts of light losses in the optic materials which are used in the shortwave and longwave range of the optical specter require the development of mirror and mirror-lens systems. An advantage of these systems is the increased light transmission, small length and the possibility to correct the chromatic abberations. It should only be noted that in the two-component pancratyc systems with reflecting planes with constant optic characteristics there is a danger of illumination of the image plane by side rays – side illuminations. In two-mirror pancratyc system for a collimator it is necessary to exclude illumination of the image plane throughout the whole range of the components movement. In the development process formulas are derived and schemes are presented which help the vizualization when calculating the diaphragm in front of two-mirror pancratyc system and calculation of diaphragm which is located between the components of two-mirror pancratyc system. The results from the calculations of a diaphragm for two-mirror pancratyc system are presented in tables. The results from research of the diaphragms for two-mirror pancratyc sysmem make us conclude that the second method of preventing the image plane from side illuminations is the preferred one. It ensured smaller sized and less change in the diaphragm length.

Diagnostic and clinical values of non-cardiac ultrasound in COPD: A systematic review

BackgroundClinical and research utility of non-cardiac ultrasound (US) in chronic obstructive pulmonary disease (COPD) has been widely investigated. However, there is no systematic review assessing the clinical values of non-cardiac...

A Study to Compare the Effect of Respiratory Muscle Stretch Gymnastic (RMSG) and Diaphragmatic Breathing on Pulmonary Function Test among Geriatric Population– An Interventional Study

Introduction : Aging is the universal phenomenon, India is the Second Largest country in the world with 72 million elderly person in 2011. It is suspected that it will be 172 millions by 2031.People above the age of 60 years are consider as Geriatric. Aging is associated with decrease in lung compliance and Thoracic Mobility. Kyphotic curvature of spine occurs due to aging, which increases AP diameter of the thorax. Increase in AP diameter of thorax alters the curvature & optimal length of Diaphragm and decreases its force generation capacity. Also due to poor posture Shoulder Quadrant muscle undergoes Shortening due to which pump handle and bucket handle movement do not occur properly, ultimately reducing the Thoracic Mobility & Flexibility. So there is a need to improve Pulmonary function among Geriatric Population. Aim : To compare the effect of respiratory muscle stretch gymnastic (RMSG) and diaphragmatic breathing on pulmonary function test among geriatric population Objectives : (1)To find out the effect of RMSG on FEV1, FVC and FEV1/FVC ratio in geriatric population (2) To find out the effect of diaphragmatic breathing on FEV1 ,FVC and FEV1/FVC ratio in geriatric population (3) To compare the effect of RMSG & diaphragmatic breathing on FEV1 ,FVC and FEV1/FVC ratio in geriatric population. Method: Subjects who fulfil exclusion and inclusion criteria were selected by purposive sampling and were assigned to group A and group B by simple random sampling. They were explained about the study, its usefulness and written consent were taken. 60 subjects were divide into two Groups: Group A: 30 subjects were given RMSG Group B: 30 subjects were given Diaphragmatic Breathing. Results: Data were analyzed using software SPSS version 20 . Paired t-test was applied within the group and Unpaired t-test was applied between the two groups. Pre-treatment and post-treatment FVC, FEV1 and FEV1/FVC ratio was analyzed, it showed statistically significant (P value < 0.05) difference in both the group but when comparison was done between two groups, it was statistically non-significant (P value > 0.05). Conclusion: Respiratory Muscle Stretch Gymnastic and Diaphragmatic breathing both were effective in improving pulmonary functions in geriatric population after performing breathing techniques for consecutive 3 days (once a day). But there was no significant difference between the two Groups in improving pulmonary function in geriatric population.

Design and sensitivity analysis of capacitive MEMS pressure sensor for blood pressure measurement

This paper presents the design and simulation of a MEMS based clamped capacitive pressure sensor for blood pressure measurement. Normally, Blood pressure for human beings varies in the range of 0.1–0.14 MPa. The operating range of this sensor design, modified according to the dimensions, is between 0 and 0.16 MPa. The diaphragm deflects on application of pressure which triggers a change in the capacitance between diaphragm and bottom electrode. The plates are separated by a dielectric medium ( $$ Si_{3} N_{4} $$ ). The change in capacitance, capacitive sensitivity and diaphragm deflection are observed for every design model to determine its performance. To improve the sensor performance, parameters like separation gap and diaphragm thickness are varied. The length and width of square diaphragm and overlapping area (A) are constant for all the designs. Small deflection theory ( $$ w_{\hbox{max} } = {h \mathord{\left/ {\vphantom {h 4}} \right. \kern-0pt} 4} $$ ), pull-in voltage phenomena ( $$ w_{\hbox{max} } \le {g \mathord{\left/ {\vphantom {g 4}} \right. \kern-0pt} 4} $$ ), and thin plate theory ( $$ h \cong a/10 $$ ) have been considered while designing the model. With respect to pressure, the simulation of diaphragm deflection is performed in COMSOL Multiphysics and analytical simulation for Change in capacitance and Capacitive sensitivity is performed in MATLAB.

NONLINEAR LAGER DEFORMATION ANALYSIS OF SINGLE ARC BELLOWS DIAPHRAGM

The single arc bellows diaphragm is regarded as the combined structure of a circular plate with initial deflection by the method of simulated shell. Based on nonlinear large deflection bending theory, the nonlinear large deformation of a single circular diaphragm is analyzed. Taking the maximum deflection of the circular part of the diaphragm as a perturbation parameter and using modified iteration method of theory of plates and shells, the nonlinear large deformation of a single circular arc bellows diaphragm with one end fixed and another end free is solved. Under boundary conditions and continuity conditions, quadratic nonlinearity analytical solutions with higher accuracy are obtained. According to the vector height of the arc and the wavelength of the arc in a single circular arc bellows diaphragm, the characteristic curve of the maximum deflection of the arc is drawn. The characteristic curve is analyzed, the deflection of the diaphragm nonlinearly increases with the increase of the vector height of the single arc diaphragm, and the deflection of the diaphragm nonlinearly increases with the increase of the arc length of the single arc bellows diaphragm.

Integrity of the Urethral Sphincter Complex, Nerve-sparing, and Long-term Continence Status after Robotic-assisted Radical Prostatectomy

BackgroundThe applicability of the sphincter complex integral theory to robotic-assisted radical prostatectomy (RARP) is unclear, with little known about the long-term effect of sphincter complex integrity on continence. ObjectiveTo determine whether the preoperative anatomical and functional features of the sphincter complex and the degree of nerve-sparing affect long-term continence after RARP. Design, setting, and participantsProspective study of 529 patients who underwent RARP at a single tertiary center. Outcome measurements and statistical analysisAnatomical factors, including membranous urethral length (MUL) and pelvic diaphragm length (PDL), were assessed using sagittal views of preoperative magnetic resonance imaging. MUL was defined as the distance from the posterior prostate apex to the urethra level at the penile bulb, and PDL was defined as the length of the urethra that met the planes created by the pelvic floor muscles. Functional parameters including maximum urethral closure pressure (MUCP) and functional urethral length were evaluated using preoperative measurements of the urethral pressure profiles. The degree of nerve-sparing was stratified as bilateral, unilateral, or none. Continence (pad-free status) was assessed according to anatomical and functional factors and nerve-sparing. We used binary logistic regression to assess factors predicting continence return 12 mo after RARP. Results and limitationsContinence return rates 1, 3, 6, and 12 mo after RARP were 39.7%, 66.0%, 80.2%, and 87.0%, respectively. Continence return rates at 12 mo differed significantly in patients with MUL ≥11.7mm (91.9%) and <11.7mm (79.9%), PDL ≥9.9mm (96.7%) and <9.9mm (74.5%), and MUCP ≥66 cmH2O (89.7%) and <66 cmH2O (79.4%). The continence return rate was significantly higher in patients with bilateral (93.0%) than in patients with unilateral (78.1%) or no (76.7%) nerve-sparing. Multivariate analysis showed that PDL (odds ratio [OR]=2.187 per mm), MUCP (OR=1.037 per cmH2O), and bilateral nerve-sparing (OR=3.671) were independently associated with continence return 12 mo after RALP. ConclusionsThe anatomical length and static pressure of the sphincter complex affected continence after RARP. Bilateral nerve-sparing was independently associated with long-term continence. Patient summaryPredisposing length and static pressure of the urinary sphincter affect continence after robotic-assisted radical prostatectomy. Nerve bundle preservation during surgery enhances postoperative return of continence.

Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients

BackgroundPulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes.MethodsTwenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program.ResultsWe found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively.ConclusionDiaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients.

Numerical simulation of the effects of diaphragm length on potential flow around a circular cylinder with rear diaphragm

Numerical simulation of the effects of diaphragm length on potential flow around a circular cylinder with rear diaphragm

Effect of the design parameters on mass transfer and energy consumption inside a lithium electrolysis cell

A 2D axisymmetric electrochemical model of a lithium experimental cell is solved using a finite element method. The model is considering the coupled effect of momentum, electric, kinetic and mass transfer phenomena. The dense diaphragm used in the setup, which is not hydraulically permeable, separates the cell into two regions: 1 (a) turbulent region, between the anode and the diaphragm, and 2 (a) laminar region between the diaphragm and the cathode. The k-epsilon model is used to solve the turbulent flow resulting from bubbles generation at the anode. A two-phase flow model is also developed to simulate the volume fractions of bubbles and electrolyte in the cell. The non-uniform bubbles distribution over the anode surface, derived from the non-uniform current distribution, has been added to the two-phase model. The effects of the diaphragm length, position and porosity on the electric and two-phase flow fields are simulated. In fact, the diaphragm position and length both influence the current distribution at the surface of electrodes and the velocity distribution in the cell, all of which influence ohmic and kinetic overpotentials. The results show that up to 40% of energy can be saved when running the lithium electrolysis cell with a shorter porous diaphragm located as far as possible from the anode. The maximum current density, found at the bottom corner of anode, is higher when the diaphragm is longer and when it is closer to the anode.

Semi-Automated Analysis of Diaphragmatic Motion with Dynamic Magnetic Resonance Imaging in Healthy Controls and Non-Ambulant Subjects with Duchenne Muscular Dystrophy.

Subjects with Duchenne Muscular Dystrophy (DMD) suffer from progressive muscle damage leading to diaphragmatic weakness that ultimately requires ventilation. Emerging treatments have generated interest in better characterizing the natural history of respiratory impairment in DMD and responses to therapy. Dynamic (cine) Magnetic Resonance Imaging (MRI) may provide a more sensitive measure of diaphragm function in DMD than the commonly used spirometry. This study presents an analysis pipeline for measuring parameters of diaphragmatic motion from dynamic MRI and its application to investigate MRI measures of respiratory function in both healthy controls and non-ambulant DMD boys. We scanned 13 non-ambulant DMD boys and 10 age-matched healthy male volunteers at baseline, with a subset (n = 10, 10, 8) of the DMD subjects also assessed 3, 6, and 12 months later. Spirometry-derived metrics including forced vital capacity were recorded. The MRI-derived measures included the lung cross-sectional area (CSA), the anterior, central, and posterior lung lengths in the sagittal imaging plane, and the diaphragm length over the time-course of the dynamic MRI. Regression analyses demonstrated strong linear correlations between lung CSA and the length measures over the respiratory cycle, with a reduction of these correlations in DMD, and diaphragmatic motions that contribute less efficiently to changing lung capacity in DMD. MRI measures of pulmonary function were reduced in DMD, controlling for height differences between the groups: at maximal inhalation, the maximum CSA and the total distance of motion of the diaphragm were 45% and 37% smaller. MRI measures of pulmonary function were correlated with spirometry data and showed relationships with disease progression surrogates of age and months non-ambulatory, suggesting that they provide clinically meaningful information. Changes in the MRI measures over 12 months were consistent with weakening of diaphragmatic and inter-costal muscles and progressive diaphragm dysfunction. In contrast, longitudinal changes were not seen in conventional spirometry measures during the same period. Dynamic MRI measures of thoracic muscle and pulmonary function are, therefore, believed to detect meaningful differences between healthy controls and DMD and may be sensitive to changes in function over relatively short periods of follow-up in non-ambulant boys with DMD.

Evaluation of indirect measures of neural inspiratory time from invasive and noninvasive recordings of respiratory activity.

Measuring diaphragmatic electromyography (EMGdi) provides an indirect quantification of neural respiratory drive and allows the delimitation of diaphragm neural activation and deactivation during inspiration. EMGdi recordings have been incorporated in novel modes of assisted mechanical ventilation, such as neurally adjusted ventilatory assist (NAVA), to trigger and cycle-off the ventilator. The EMGdi signal improves the assistance delivered by more conventional ventilatory modes, in which the ventilator is synchronized with the patient employing a pneumatic triggering. In this work, we evaluate the time delay between the onset and offset of inspiratory activity estimated from EMGdi and three respiratory mechanical signals: the respiratory flow (FL), the transdiaphragmatic pressure (Pdi) and the diaphragm length (Ldi) signals. To this purpose, these signals were acquired in three mongrel dogs surgically instrumented under general anesthesia. Onsets and offsets were estimated manually and by automatic algorithms on these signals. The highest delays were obtained between EMGdi and FL (100 ms) while the lowest delays were obtained between EMGdi and Pdi (8 ms). Moreover, differences between manual and automatic estimations showed a mean absolute error lower than 45 ms. In conclusion, our study points out that both EMGdi and Pdi signals detect the onset and offset of inspiratory activity earlier than the FL signal, and would therefore be better for the improvement of patient-ventilator synchrony.

The research on active flow control method with vibration diaphragm on a NACA0012 airfoil at different stalled angles of attack

The flow control method with vibration diaphragm as a relatively new active flow control method has shown its great potential of improving flow field. A two-dimensional numerical computation for flow over an airfoil with vibration diaphragm is present at different stalled angles of attack and Re=1.2×105. The vibration diaphragm is placed at the suction side of the airfoil surface near the leading edge and the length of the vibration diaphragm's projection along the chord direction is 0.1c. The effects of the dependant parameters dimensionless amplitude and frequency and the optimum parameters varying with different stalled angles of attack are investigated through enormous simulation data. Numerical results show that the lift coefficient and the lift-to-drag ratio increase firstly with the growth of the dimensionless frequency and then decrease. There exists the optimum dimensionless amplitude to make the control method behave best. The maximum increment of lift coefficient occurs at the low dimensionless frequency near 0.5, whereas for the lift-to-drag ratio, the maximum increment is attained the value of dimensionless frequency ranging from 1 to 1.5 at 16 degree angle of attack, the greatest improvement of the lift-to-drag ratio occurs when the value of dimensionless amplitude and frequency are 0.015 and 1.4, the maximum percent improvement is 91.31%. The oscillation coefficient is found to be a critical parameter to affect the lift-to-drag ratio of the airfoil and there exits an optimum oscillation coefficient to obtain greatest improvement of lift-to-drag ratio. The optimum parameters of the control methods to achieve the highest lift-to-drag ratio vary with different stalled angles of attack, with the growth of the angles of attack, the optimum dimensionless amplitude increases, the optimum dimensionless frequency decreases firstly and then keep the certain value 1.1 and the oscillation coefficient fluctuates weakly in the range of 1.15–1.3.

Numerical Analysis of the Effect of Diaphragm Length, Position and Porosity on the Electric Field and Mass Transport inside a Lithium Electrolysis Cell

Lithium is commercially produced by the electrolysis of lithium chloride. This process is expensive due to the high energy consumption of the electrolysis process. A noticeable part of the energy lost in this electrochemical cell is caused by back reactions, essentially between chlorine bubbles produced at the anode and liquid lithium produced at the cathode. The diaphragm has two opposite effects on the cell energy consumption: it increases the current efficiency through its preventive effect on back reactions; however, it increases the energy consumption of the cell by introducing extra ohmic overpotential. Furthermore, in a lithium electrolysis cell, the diaphragm characteristics significantly influence the mass transfer, electric and velocity fields. A 2D axisymmetric electrochemical model of a lithium production cell is solved using a finite element method and used to minimize the cell energy consumption by optimizing the diaphragm characteristics and its position in the cell. The model is considering the coupled effect of momentum, electric, kinetic and mass transfer phenomena. The diaphragm separates the cell in two regions: 1- a turbulent region, between the anode and the diaphragm, and 2- a laminar region between the diaphragm and the cathode. The k-ε model is used to solve the turbulent flow resulting from bubbles generation at the anode. The bubbles cause an ohmic overpotential and hyperpolarization, considered through the resistive layer and bubble coverage at the surface of the anode. Furthermore, the effects of the diaphragm length, position and porosity on the electric field are simulated. In fact, the diaphragm position and length influence the current distribution at the surface of electrodes and the velocity distribution in the cell all of which influence ohmic and kinetic overpotentials. The experimental cell, simulated as a base case on which the model has been validated, contains a dense alumina diaphragm. The results show that up to 40% energy is saved when running a lithium electrolysis cell with a smaller porous diaphragm located as far as possible from the anode. Moreover, the diaphragm deteriorates the current density distribution along the electrodes with a detrimental effect to the integrity of the electrodes. The maximum current density, found at the bottom corner of anode, is higher when the diaphragm is longer and when it is closer to the anode. Finally, but not least, the results of this research are not only useful for improving the design of lithium production cells. They also could be extended and applied to the study of other molten salts electrochemical cells equipped with diaphragm.

A Mitigation Technique to Reduce Ground Settlements Induced by Tunnelling Using Diaphragm Walls

Ground movements due to the excavation of shallow tunnels may cause damage or loss of functionality to nearby buildings: embedded diaphragm walls pre-installed between the tunnel and the building can be effective in reducing these movements thus preventing damage on existing structures. Plane strain finite element analyses are first presented in the paper in which a continuous diaphragm made by adjacent panels was modelled to evaluate the effects of different geometrical and mechanical parameters. For a limited set of these parameters, 3D FE analyses were also performed maintaining a plane strain excavation scheme to evaluate the effectiveness of an infinite diaphragm made by closely spaced piles. A 3D study is finally presented in which the horizontal diaphragm length needed to attain the same efficiency provided by an infinite diaphragm is evaluated. Completion of tunnel construction was assumed in both 2D and 3D studies.