Increase In Peak Pressure Research Articles

Research and evaluation of turbulent jet ignition mode for improving combustion performance of ethanol rotary engine

Improving the combustion performance of ethanol rotary engine (ERE) is crucial for enhancing energy efficiency and reducing emissions, particularly in the context of global emission reduction efforts. Although the application of ethanol as a clean alternative fuel is growing, research on optimizing its combustion in rotary engines remains limited. The novelty of this work lies in the comparison of two ignition modes: the conventional spark plug ignition mode (CSPIM) and the turbulent jet ignition mode (TJIM). Experimental validation and numerical simulation methods were employed to evaluate the effects of these two ignition modes on in-cylinder flow field and combustion characteristics. The results indicate that, compared to the CSPIM, the use of the TJIM significantly improves turbulence intensity, increases peak pressure, reduces combustion duration, and expands the flame propagation area, leading to an average increase of 0.42 kW in the power output of the ERE. Furthermore, the use of the TJIM leads to a 130 % average increase in NO mass produced in the cylinder, while CO emissions are reduced by 40 % on average. These findings demonstrate that the TJIM has significant potential to improve the combustion performance of ERE, offering considerable advantages in both efficiency and emissions control.

Beyond support: exploring the dynamic and static biomechanical changes induced by preventive ankle taping: a novel cross-sectional study

Introduction In sports, 80% of all ankle injuries are sprains of the external compartment. Functional bandages are usually used preventively, specially in individuals with a history of lateral ankle injuries. To this day, the actual benefits of such taping remain unknown as important modifications are introduced in the ankle biomechanics. Objective The aim of the present study is to describe the biomechanical processes underlying these effects, such as modification during stance times, balance, contact surface and maximum and average pressures in the rearfoot, forefoot and midfoot, using a sprain preventive taping for the external ankle compartment. Methods An observational, analytic, cross-sectional study was designed. Data from static and dynamic plantar pressures with a pressure platform and balance data assessed with the Y Balance Test (YBT) were analysed in 50 participants (age = 21.00 ± 2.34 years, weight = 71.11 ± 13.12 kg, height = 1.75 ± 00.9 m, BMI = 22.94 ± 2.50 kg/m2, foot size = 41.60 ± 3.00) with and without preventive functional taping for lateral ankle sprain (LAS). Results A statistically significant decrease in YBT was observed in the taped participants toward anterior (p = 0.001) and posterolateral (p = 0.005) motion. On the static measures at the pressure platform, an increase in peak pressure at the midfoot (p = 0.001), a decrease in the maximum pressure in the forefoot (p = 0.003) and a decrease in the contact surface in the rearfoot (p = 0.003) were recorded. Dynamic measures at the pressure platform analysis showed a statistically significant decrease in contact surface at the rearfoot (p = 0.001), an increase in mean pressure in both the midfoot (p = 0.044) and forefoot (p = 0.001) and a significant decrease in velocity in the forefoot (p = 0.003). Conclusions In conclusion, we observed that ankle taping led to increased peak pressures in the midfoot and decreased maximum pressures in the forefoot, indicating a shift in load distribution within the plantar surface. Simultaneously, a significant reduction in the velocity at the forefoot during dynamic tasks suggests that taping may alter natural gait dynamics, potentially affecting movement efficiency and stride characteristics. In addition, the application of ankle taping significantly altered balance, as evidenced by a decrease of YBT scores anterior and posterolateral directions. Prophylactic taping in patients with no prior history of LAS is not recommended.

Computational investigation of combustion and emission characteristics of HCCI engine fueled with Carbon-Free NH3 –H2O2 blend

A computational investigation is provided of the utilization of blends of NH3 and H2O2 as carbonless fuels for HCCI combustion. A Computational Fluid Dynamics (CFD) model is developed and validated to assess the engine’s performance under varying proportions of NH3 and H2O2, equivalence ratios, and inlet temperatures. The heat release rate profiles demonstrated dual peaks, which were rationalized as an initial fuel decomposition followed by a slow thermal explosion and then a fast depletion of the fuel after the generation of a pool of OH radicals through decomposition of H2O2. Findings suggest that an increase in mole fraction of H2O2 advances combustion. Increasing the H2O2 volume fraction also decreases combustion duration, while increasing the IMEP. In-cylinder peak pressure and Maximum Pressure Rise Rate (MPRR) increase with H2O2 mole fraction, leading to reduced thermal efficiency, particularly at higher equivalence ratios, and an increased danger of uncontrolled combustion (knocking). Additionally, higher inlet mixture temperatures were shown to result in an advancement in the start of combustion and a reduction in combustion duration, with a corresponding increase in peak pressure. This points to the possibility of potentially controlling the notoriously difficult-to-control HCCI combustion through intake temperature for NH3/H2O2 fuel blends. However, increased NOx emissions are observed for increased intake temperature and in any case the NOx emissions are orders of magnitude above current regulatory limits, which means that practical engine operation will only be possible with an aftertreatment scheme based on the de-NOx activity of NH3.

Computational modeling of predicting cerebrovascular injury in traumatic brain injury patients

Despite significant progress in understanding traumatic brain injury (TBI) and subsequent outcomes, predicting and preventing cerebrovascular injury (CVI) remains challenging. We introduces a novel computational modeling approach using advanced fluid-structure interaction (FSI) models, which incorporate high-resolution magnetic resonance imaging (MRI) data to analyze changes in intracranial pressure and blood flow in cerebral arteries post-TBI. We analyzed the mechanical fields between the PCOMA, ICA, PCA, and ACA areas by conducting a region of interest analysis in this research. The approach uniquely integrates detailed patient-specific brain vasculature geometries and dynamic boundary conditions to enhance predictive accuracy. The model indicates that peak pressure in the anterior cerebral artery (ACA) reaches 130 kPa within the first hour post-injury, with a 20% increase observed at 2 milliseconds. Wall shear stress (WSS) in the posterior communicating artery (PCOMA) reaches 140 kPa, which exceeds the typical physiological range of 10–20 kPa and may lead to endothelial damage. Regions such as the PCOMA and ACA are identified as particularly vulnerable to high mechanical stress and strain, which suggests the need for timely medical intervention to reduce the risk of CVI. Further validation with clinical data is required to improve the predictive accuracy of the model.

Can Contrast Injections Cause or Propagate Coronary Injuries? Insights From Vessel and Guiding Catheter Hemodynamics.

The mechanistic association between the hydraulic forces generated during contrast injection and the risk of coronary injury is poorly understood. In this study, we sought to evaluate whether contrast injections increase intracoronary pressures beyond resting levels and estimate the risk of hydraulic propagation of coronary dissections. This is a prospective, single-arm, multicenter study that included patients with nonculprit, non-flow-limiting coronaries. A continuous 60-second pressure recording was taken at 5 predetermined locations during contrast injections: distal, mid, and proximal vessel, catheter tip, and inside the catheter. The primary end point was the change in intracoronary peak pressure between resting and injections in each location. A total of 269 pressure recordings (58 vessels; 52 patients) were analyzed. Injections led to a small increase in peak pressure in the distal (mean difference, +4.5 mm Hg; 95% CI, 1.5-7.4), mid (mean difference, +4.1 mm Hg; 95% CI, 1.4-6.9), and proximal (mean difference, +5.1 mm Hg; 95% CI, 2.5-7.7) vessel locations, and much higher increases at the catheter tip (mean difference, +11.7 mm Hg; 95% CI, 5.8-17.7) and inside the catheter (mean difference, +77.5 mm Hg; 95% CI, 64.5-90.4). Compared to the distal vessel, pressure changes were only significant at the catheter tip (+10 mm Hg; P < .01) and inside the catheter (+79.1 mm Hg; P < .01). Contrast injections lead to negligible changes in intracoronary pressures beyond the catheter tip. Although it is sensible to minimize injections when coronary dissections are close to the catheter, it is unlikely that they would cause injuries beyond the catheter tip.

Downcycled neat LDPE plastic wastes fuelled CI engine’s carbon and soot emission reduction with an elevated performance by Acetylene (HC[tbnd]CH) premixed combustion

Wastes are not useless, but they are used less. Wastes can be reduced by utilization not by destroying. The unobserved single-used low-density polyethylene (LDPE) plastic wastes are the sources that produce the fuel energy for the CI engines by pyrolysis. This downcycles the LDPE wastes. This neat LDPE plastic waste pyrolysis oil (LPWPO) has lower performance and slightly higher carbon emissions than diesel. To rectify this challenge, a premixed charge of air–acetylene is inducted into a 1500 rpm 5.2 kW CI engine at 1–4 lpm of flow rate. Acetylene is admitted into the inlet manifold to vary the mixture strength. Up to 26 % of acetylene energy share is involved in the premixed combustion with LPWPO. At full load,4 lpm of acetylene induction with LPWPO oil produced 14.05 %, and 22.96 % increased BTE, and peak pressure than neat LPWPO respectively. At the same condition have 61.35 %, 87.5 %, 31.84 %, 22.64 % percentage reduction in soot (7.11 g/kWh), CO (3.71 g/kWh), UHC (0.18 g/kWh), and CO2 (732.1 g/kWh) emission than neat LPWPO respectively. However, the increased peak pressure increases the NOx emission. Therefore, Acetylene (4 lpm) induction with LPWPO is recommended for improved performance with reduced carbon and soot emissions. This method supports the LPWPO oil use in CI engines and indirectly supports the downcycling of single-use LDPE plastic waste in the environment.

Innovative research on waste tire recycling for sustainable biofuel production: Assessment of its usability on multi-cylinder diesel engine employing constant injection of oxyhydrogen and biogas through a premixing device

This study investigates the production of waste tire pyrolyzed oil on a laboratory scale and its potential use as a fuel along with biogas and hydrogen in a variable-speed transportation engine. The pyrolyzed oil, obtained from waste tire pieces through a lab-scale plant, undergoes distillation and is blended with diesel fuel in a 20% ratio. This blended fuel is supplied to a multi-cylinder variable-speed transportation engine, either alongside biogas or HHO separately or both combined, at fixed flow rates with air passage through a premixing device (venturi). This study aimed to assess engine combustion characteristics such as in-cylinder pressure and heat release rate; performance parameters, including brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC), as well as emissions of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). The results indicate that using pyrolyzed oil in unmodified diesel engines reduces combustion characteristics and performancewhile increasing HC and NOx emissions and decreasing CO emissions. In addition, supplying biogas and the fuel mixture further deteriorates combustion and performance, while increases HC and CO emissions, and reduces NOx emissions. The focus of the present research is to evaluate the impact of adding green hydrogen (HHO) gas to a pyrolyzed oil fuel mixture and a biogas-led fuel mixture in a compression ignition (CI) engine. The results indicate that the addition of hydrogen enhances combustion characteristics, engine performance and reduces emissions, except for NOx. Specifically, there is an increase in cylinder peak pressure and HRR by around 6–10% range, improvement in BTE by 16–20% and BSFC by 5–7%, along with a decrease in HC and CO emissions by 13–16% and 11–13%, respectively. However, there is an increase in NOx emissions of 6–9%. In essence, the addition of green hydrogen enhances engine performance and reduces emissions in waste tire-derived pyrolyzed oil and biogas blends, indicating a viable path for sustainable transportation fuel.

Impacts of three inspiratory muscle training programs on inspiratory muscles strength and endurance among intubated and mechanically ventilated patients with difficult weaning: a multicentre randomised controlled trial

BackgroundInspiratory muscle training (IMT) is well-established as a safe option for combating inspiratory muscles weakness in the intensive care setting. It could improve inspiratory muscle strength and decrease weaning duration but a lack of knowledge on the optimal training regimen raise to inconsistent results. We made the hypothesis that an innovative mixed intensity program for both endurance and strength improvement could be more effective. We conducted a multicentre randomised controlled parallel trial comparing the impacts of three IMT protocols (low, high, and mixed intensity) on inspiratory muscle strength and endurance among difficult-to-wean patients.MethodsNinety-two patients were randomly assigned to three groups with different training programs, where each performed an IMT program twice daily, 7 days per week, from inclusion until successful extubation or 30 days. The primary outcome was maximal inspiratory pressure (MIP) increase. Secondary outcomes included peak pressure (Ppk) increase as an endurance marker, mechanical ventilation (MV) duration, ICU length of stay, weaning success defined by a 2-day ventilator-free after extubation, reintubation rate and safety.ResultsMIP increases were 10.8 ± 11.9 cmH2O, 4.5 ± 14.8 cmH2O, and 6.7 ± 14.5 cmH2O for the mixed intensity (MI), low intensity (LI), and high intensity (HI) groups, respectively. There was a non-statistically difference between the MI and LI groups (mean adjusted difference: 6.59, 97.5% CI [− 14.36; 1.18], p = 0.056); there was no difference between the MI and HI groups (mean adjusted difference: − 3.52, 97.5% CI [− 11.57; 4.53], p = 0.321). No significant differences in Ppk increase were observed among the three groups. Weaning success rate observed in MI, HI and LI group were 83.7% [95% CI 69.3; 93.2], 82.6% [95% CI 61.2; 95.0] and 73.9% [95% CI 51.6; 89.8], respectively. MV duration, ICU length of stay and reintubation rate had similar values. Over 629 IMT sessions, six adverse events including four spontaneously reversible bradycardia in LI group were possibly related to the study.ConclusionsAmong difficult-to-wean patients receiving invasive MV, no statistically difference was observed in strength and endurance progression across three different IMT programs. IMT appears to be feasible in usual cares, but some serious adverse events such as bradycardia could motivate further research on the specific impact on cardiac system.Trial registration Clinicaltrials.gov identifier: NCT02855619. Registered 28 September 2014

Effects of wire size on electrical and shock-wave characteristics in underwater electrical explosions of aluminum wires

Initial wire resistance is an important parameter in an underwater electrical wire explosion because it directly affects the discharge characteristics of the circuit and indirectly affects the explosion and shock-wave generation. This paper presents a study on how the initial resistance affects electrical and shock-wave characteristics of underwater electrical explosions of aluminum wires with an initial energy storage of ∼53.5 kJ under the optimal mode. Load voltage, circuit current, and shock-wave pressure were recorded and analyzed. The experimental results show that the average of the discharge channel resistance and the total energy deposition all increase with the initial resistance. In addition, there is no simple functional relationship between the energy deposition during the phase transition process and the initial resistance, while the energy deposition during the plasma growth process increases with the initial resistance. As for shock waves at ∼33 cm, it is observed that when the initial resistance increases from 674.82 to 1581.60 μΩ, the peak pressure, energy density, and impulse increase from 12.65 MPa, 2.67 kJ/m2, and 964.51 Pa s to 42.37 MPa, 18.21 kJ/m2, and 1940.42 Pa s, respectively. In other words, for the optimal mode, an underwater electrical explosion with thinner and longer wire is more conducive to generating strong shock waves in the far-field regime. These results should help select loads for underwater electrical wire explosions in engineering applications.

Perforation performance and mechanism of a torch utilizing Al/PTFE/Fe2O3/CuO thermite composites

Aluminum-based thermite containing fluorine oxidizers exhibits excellent performance characteristics such as substantial heat release and tunable gas production. In this study, a torch loaded with Al/PTFE/Fe2O3/CuO thermite composites was recently designed to eject high-temperature jets and penetrate 10 mm-thick Q235 steel plates. The reactivity of the loading composites was systematically studied to analyze the perforation mechanism. The microstructure, the flame temperature, and pressure properties of the thermites were tested. The device’s perforation capacity was quantified. The research confirmed the application potential of fluoropolymer-based thermites in the field of metal perforation. The results of the pressure tests suggest that the composites have a synergistic effect on pressure properties, resulting in better peak pressure than single thermite. The fuel-rich thermite exhibited a higher flame temperature and heat of combustion. It is observed that the perforation velocity increased with the increase in flame temperature and peak pressure. By adjusting the Al and PTFE content of the near fuel-rich thermites, the torch with different equivalence ratios exhibited a tunable perforation time ranging from 0.4 s to 5.21 s. It is hypothesized that the formation of the alloy layer on the surface of the metal targets plays a significant role in the perforation process by weakening the strength of the plates and improving the mobility of the molten area. The results provide a new and practical path to designing efficient perforation agents.

Exploring the coupling mechanism between piston structure and turbulent jet ignition mode in hydrogen mixed natural gas rotary engines

The rapid development of electric vehicles has drawn extensive attention to using rotary engines as small-scale power generation devices. However, their wide application has been limited by drawbacks such as low combustion efficiency and high emissions. Therefore, to obtain rotary engines with high combustion efficiency and low emissions, this study explored the strengthening effect of natural gas/hydrogen hybrid fuel (NHHF) and Triangular Rotor Piston (TRP) structure on the combustion in the turbulent jet ignition rotary engine (TJI-RE) at different ignition advance angles (IAAs). Additionally, an experimental platform and a three-dimensional computational model for TJI-RE fueled by natural gas/hydrogen hybrid fuel (NHHF) were established in this study. The research results indicated that the TRP structure altered the combustion process by affecting the ignition area in the ignition stage and the turbulence kinetic energy during the combustion stroke. Furthermore, the SC-shaped cylinder exhibited the highest peak pressure for any fixed IAA. When the IAA was fixed at 30°CA (BTDC), the TJI-RE with the SC-shaped cylinder experienced a 12.12% increase in peak pressure and a 4.1% increase in indicated work compared to the FP-shaped cylinder. Additionally, the CO emission was reduced by 13.79%, while the NO emission showed a significant increase.

Peroneus Brevis to Longus Tendon Transfer in the Treatment of Flexible Progressive Collapsing Foot Deformity: A Cadaveric Study.

Although operative treatment of the flexible progressive collapsing foot deformity (PCFD) remains controversial, correction of residual forefoot varus and stabilization of the medial column are important components of reconstruction. A peroneus brevis (PB) to peroneus longus (PL) tendon transfer has been proposed to address these deformities. The aim of our study was to determine the effect of an isolated PB-to-PL transfer on medial column kinematics and plantar pressures in a simulated PCFD (sPCFD) cadaveric model. The stance phase of level walking was simulated in 10 midtibia cadaveric specimens using a validated 6-degree of freedom robot. Bone motions and plantar pressure were collected in 3 conditions: intact, sPCFD, and after PB-to-PL transfer. The PB-to-PL transfer was performed by transecting the PB and advancing the proximal stump 1 cm into the PL. Outcome measures included the change in joint rotation of the talonavicular, first naviculocuneiform, and first tarsometatarsal joints between conditions. Plantar pressure outcome measures included the maximum force, peak pressure under the first metatarsal, and the lateral-to-medial forefoot average pressure ratio. Compared to the sPCFD condition, the PB-to-PL transfer resulted in significant increases in talonavicular plantarflexion and adduction of 68% and 72%, respectively, during simulated late stance phase. Talonavicular eversion also decreased in simulated late stance by 53%. Relative to the sPCFD condition, the PB-to-PL transfer also resulted in a 17% increase (P = .045) in maximum force and a 45-kPa increase (P = .038) in peak pressure under the first metatarsal, along with a medial shift in forefoot pressure. The results from this cadaver-based simulation suggest that the addition of a PB-to-PL transfer as part of the surgical management of the flexible PCFD may aid in correction of deformity and increase the plantarflexion force under the first metatarsal. This study provides biomechanical evidence to support the addition of a PB-to-PL tendon transfer in the surgical treatment of flexible PCFD.

Preparation and properties of nano B/NC/AP@F2602 double-layer energetic fiber

The nano-boron powder (n-B) exhibits remarkable efficacy as a combustion catalyst, making it a prime candidate for use in solid propellant metal burners. Nevertheless, throughout the storage phase, the surface of n-B powder is prone to oxidation and substantial agglomeration, resulting in challenges with ignition and incomplete energy dissipation when utilizing boron powder. In this study, we utilized the coaxial electrospinning technique to produce nanofibers comprised of nano-boron /nitrocellulose/ammonium perchlorate@fluororubber (n-B/NC/AP@F2602), with the nano boron uniformly distributed within the core-shell fibers. In the course of combustion, the fibrous composite of n-B/NC/AP@F2602 undergoes an escalation in the rates of energy output and energy release, owing to the constraints imposed by external F2602((C₂H₂F₂)n and (C₃F₆)n). The n-B/NC/AP@F2602 demonstrates a 1.4-fold increase in peak pressure and a 3.6-fold increase in maximum boost rate when compared to the n-B/NC/AP. The energy performance evaluation results reveal that the mean molecular weight (MC) of combusted products from n-B/NC/AP@F2602 is 29.2 g·mol−1, representing a substantial increase compared to that of n-B/NC/AP. The aforementioned findings exemplify that coaxial electrospinning is an exceedingly efficacious technique for enhancing nanostructures, thereby amplifying the reactivity of energetic particles and offering novel insights into their application in energetic materials.

Investigation on cracking propagation patterns in hydraulic fracturing under different vug distributions: Experimental and numerical case

Natural vugs are developed in geothermal reservoirs. Communication of natural vugs can effectively improve reservoir stimulation, but the vug distribution affects its propagation pattern. In this work, large-size samples (500 × 500 × 500 mm) made of carbonate-like materials were prepared, and a series of true triaxial hydraulic fracturing tests were carried out to investigate the influence of the vug orientation and relative orientation between vugs on the propagation pattern. Moreover, the discrete element method (DEM) was used to further elucidate the effect of vug distribution on the cracking propagation mechanism. The results obtained that the increase in the vug orientation leads to an increase in peak pressure, and the relative orientation has less effect on peak pressure. In terms of propagation pattern, at low vug orientation and relative orientation (i.e. 0°, 30°), the induced crack will penetrate or deflect through the vugs, while at 45°, the induced cracks deflect but do not interpenetrate the vugs. Accordingly, numerical simulations demonstrate that the crack deflection induced by the vug is mainly due to microcracks generated by tensile stress concentration around the vugs under the pore pressure, but the high vug orientation suppresses the tensile stress domains, accompanied with an increase in the percentage of shear cracks with vug orientation. These results may improve the understanding of vuggy carbonate reservoir stimulation.

Pneumothorax during laparoscopic plication of diaphragmatic eventration: A case report

Diaphragmatic eventration is the abnormal elevation of the hemidiaphragm or part of it caused due to the lack of muscle or nerve function with normal anatomical attachments. Pneumothorax is a common occurrence during thoracoscopic approaches of diaphragmatic plication but a very rare complication in laparoscopic approaches.A 56-year-old male presented with complaints of pain in the left upper abdomen, bloating, and difficulty in breathing. He was diagnosed with idiopathic diaphragmatic eventration and was taken up for laparoscopic plication under American society of anaesthesiologists – physical status 1. Intra-op, he developed sudden onset increase in peak pressures with poor tidal volumes and desaturation. Examination revealed reduced breath sounds and movement of left side of chest, possibly a left sided pneumothorax. The placement of a left-sided intercostal chest drain led to improvements in ventilatory parameters.The patient was successfully extubated following the completion of surgery.: Pneumothorax is an established complication of laparoscopic surgery, with a reported incidence of 0.01%-0.4%. But early detection and diagnosis of a pneumothorax intraoperatively is difficult and often missed because of controlled ventilation and pneumoperitoneum. A high index of suspicion should be maintained for early diagnosis and management of such conditions.Intraoperative tension pneumothorax and its progression can have devastating consequences. A high index of suspicion, prompt recognition of the condition despite many factors that may mask the condition and prompt remediation leads to an effective management of such cases.

Investigation of H2 enrichment of ternary blended fuel modified with graphene nanoplate on cycle-by-cycle variations

Despite the global goal of achieving e-mobility in the future, the majority of the transportation sector still heavily relies on fossil fuels. Previous studies in the area have revealed the benefits of hydrogen additives and nanoparticles mixed with blended diesel fuels on engine performance and emissions. However, there is a significant gap in the research when it comes to exploring the combination of non-metallic nanoparticle additives with alcohol and diesel blend fuels under dual-fuel mode with hydrogen. In the study, a fuel blend (BF) comprising 80% diesel, 10% n-butanol, and 10% ethanol, which represents a potential alternative fuel composition for compression ignition engines, was specifically focused on. To further enhance the fuel properties and combustion characteristics, the addition of 50 ppm graphene nanoplatelets (GNP) was introduced as a non-metallic additive. By examining this novel fuel composition and investigating its impact under both single and dual-fuel mode, the dimension of hydrogen addition in the dual-fuel mode is aimed to explore potential synergistic effects. A diesel engine was used under dual fuel mode, with hydrogen fed at a rate of 0.25 g/min. The prepared fuels were tested at 1800 rpm engine speed by applying five different loads. 50 ppm GNP of modified fuels resulted in an increase of peak pressures by 3.1%, 4.2%, and 5.6% for DGNP, BFGNP, and BFGNP15H respectively, compared to D. At full load, the COVIMEP values were approximately 0.3%, 0.2%, 0.4%, 1.3%, and 1.6% for D, DGNP, BF, BFGNP, and BFGNP15H, respectively. In the term of thermal efficiency, BFGNP15H had a 3.9% lower BTE than BFGNP at 25% load, but BFGNP15H showed a 0.4% increase in BTE at full load compared to BFGNP. For emission analysis, BFGNP15H showed a reduction of 42.31%, 15.1%, and 10% in CO emissions compared to D, BF, and BFGNP, respectively, under full load in dual operating condition. However, the NO emissions of BFGNP15H were 7.2% higher than those of D under the same condition.

Simulation of residual stress and micro-plastic deformation induced by laser shock imprinting on TC4 titanium alloy aero-engine blade

In laser shock processing (LSP) of aero-engine blades, overlap marks due to spot overlapping cause irregular surface morphology that becomes a source of cracks under fatigue behaviors. This reduces the beneficial effect of compressive residual stress induced by LSP and undermines fatigue performance of blades. In this paper, laser shock imprinting (LSI) is proposed to improve fatigue performance of aero-engine blades. In this process, a layer of contact film with micro-grooves is placed between the absorption layer and the workpiece (blade) of the LSP. By using the double action of laser shock wave and micro-grooves in contact film, blade surface morphology is transformed towards the direction conducive to improve its fatigue performance. Using ABAQUS software, Johnson-Cook model and Fabbro model were considered to study the plastic rheological behavior of blade surface material induced by LSI. Effect of process parameters namely, peak pressure, impact number and spot overlapping ratio on residual stress and micro-plastic deformation of blade surface were studied. Simulation results showed that under the action of laser shock wave, blade surface material flowed into micro-grooves in contact film via extrusion plastic deformation. This resulted in micro-bulge morphology having geometrically specific arrangement on blade surface, which achieved accurate control of micro-plastic deformation on blade surface. Increase in peak pressure and impact number increase the surface micro-bulges height. However, increase in peak pressure lowers the stress difference between bulging edge and non-bulge zones. It was found that 33% spot overlapping impact resulted in more uniform surface micro-bulge morphology on blade surface.

Performance Optimization of a Multi-groove Water Lubricated Journal Bearing with Partial Slip by Taguchi Analysis

The importance of preserving the ecological balance has paved the way for developing water lubricated bearings for marine vessels and other various applications. These bearings have found widespread applications in high pressure water pumps, water-power plants and power generation stations in sea, mining industries, ships, boats and submarines. To investigate the performance envelope of a water lubricated journal bearing (WLJB) with partial slip/no slip pattern, a multi-groove bearing model is developed and analyzed using CFD in the present study. Taguchi analysis method is utilized to determine the highest influential parameter affecting the pressure distribution and load-carrying capacity of a water lubricated journal bearing. From Taguchi method, optimum values identified for design parameters such as attitude angle, groove angle, groove height and number of grooves are 60°, 9°, 7 mm and 2, respectively. For the optimum combination model, a higher load bearing capacity of 1484.5 N is attained. Approximately, 2.88 times increase in peak pressures are noted from the current optimal bearing model by comparing with previous findings. Results indicated that the number of grooves and groove angle are the most influential parameters affecting the bearing load capacity. Partial slip conditions are applied at the grooved surfaces of a bearing model designed based on the identified optimal groove parameters. Influence of varying slip intensity on bearing load capacity is analyzed using CFD simulation. Appropriate selection of slip regions and slip amplitude is found to play a major role influencing the performance of the water lubricated journal bearing.

Features of Mechanical Lung Ventilation During Robot-Assisted Radical Prostatectomy in Patients with Different Body Mass Index

The aim of the study. To evaluate effects of carboxyperitoneum and steep Trendenburg position on respiratory biomechanics and gas exchange indicators in patients with different body mass index (BMI) during robotic-assisted radical prostatectomy (RRP). To develop an algorithm for choosing the optimal mechanical lung ventilation (MLV) regimen. Materials and methods. The study included 141 patients with verified prostate cancer who were candidates for RPR. Participants were divided into 2 groups based on BMI: group I included 88 patients with BMI30 kg/m2, group II — 53 patients with BMI30 kg/m2. Indicators of respiratory biomechanics and gas exchange during ventilation in various modes (Volume Controlled Ventilation (VCV), Pressure Controlled Ventilation (PCV), Pressure Controlled– Inverse Ratio Ventilation (PC-IRV) were analyzed in each group at 5 consecutive stages of the procedure.Results. The key parameters evidencing the effectiveness and safety of MLV during RRP procedure did not vary significantly under various ventilation regimens in the group of patients with a BMI30 kg/m2. Whilst in obese patients the use of VCV mode resulted in a significant increase of airway peak pressure (Ppeak) already at the stage of placing them into a steep Trendelenburg position (35°), thus endangering with the development of ventilator-induced lung injury. Increased Ppeak was also accompanied by the drop in oxygen saturation and significantly lower SpO₂ values, starting from the stage of applying carboxyperitoneum and until the end of surgical intervention.Conclusion. In non-obese patients, there’s no particular ventilator regimen that is crucial for achieving the safety and effectiveness of RRP anesthesia management, all regimens can be used. In patients with BMI30 kg/m2 PCV regimen and PC-IRV with inhalation/exhalation ratio of 1.5:1 can be considered as the optimal strategy for MLV during anesthesia for RRP surgery.

The Effect of the Isolator Size on the Efficiency of Rotary Piston Compressors

A hybrid renewable-hydrogen green energy system combines renewable energy sources with hydrogen production and storage technologies to create a sustainable and efficient energy system. One of the major components of such systems is compressors, which influence the system’s overall efficiency. Therefore, this research paper will study design modifications that improve the efficiency of these components. More precisely, this study examines the correlation between a concentric rotary piston compressor isolator size and efficiency. The objective is to determine the significance of size on the compressor’s performance. Two distinct mechanisms and operational designs employed in such compressors are investigated. Irrespective of the compressor design, it is revealed that the isolator’s diameter considerably impacts the pressure ratio of these rotary compressors. Specifically, the conclusion is that a larger isolator increases efficiency; a 35% larger RSP diameter results in a 145% increase in peak pressure for Mechanism 1. A 100% larger RSP diameter yields a 180% boost in peak pressure for Mechanism 2.