Geometric Ratio Research Articles

Evaluation of ammonia-gasoline co-combustion in a modern spark ignition research engine

Ammonia (NH3) is emerging as a potential favoured fuel for longer range decarbonised heavy transport, particularly in the marine sector, predominantly due to highly favourable characteristics as an effective hydrogen carrier. This is despite generally unfavourable combustion and toxicity attributes, restricting end use to applications where robust health and safety protocols can always be upheld. In the currently reported work, a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling, with the aim of understanding maximum viable ammonia substitution ratios across the speed-load operating map. The work was conducted at varied effective compression ratios under overall stoichiometric conditions, with the spark timing re-optimised for maximum brake torque at all stable logged sites. The experiments included industry standard measurements of combustion, performance, and engine-out emissions (including NH3 “slip”). With a geometric compression ratio of 11.2:1, it was found possible to run the engine on pure ammonia at low engine speeds (1000-1800 rpm) and loads of 12 bar net IMEP. When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire. When operating at 1800 rpm and 12 bar net IMEP, all emissions of carbon (CO2, CO, unburned hydrocarbons) and NOx decreased considerably when switching to higher NH3 substitution ratios, with NOx reduced by ~ 45% at 1800 rpm/12 bar when switching from pure gasoline to pure NH3 (associated with longer and cooler combustion). By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio, it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state (e.g., linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP). Under all conditions, the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH3. Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map.

Nonlinear geometric fluid-structure interaction model of multilayered sandwich plates in contact with unbounded or bounded fluid flow

Based on the Kirchhoff-Love theory and von Kármán's geometric nonlinearity, the nonlinear vibration analysis of multilayered sandwich plates under ideal flow is presented. Rectangular plates are considered to be laminated of orthotropic composite layers as upper and lower face sheets as well as a central lightweight core made of functionally graded (FG), anisogrid lattice or metal foam materials. Three coupled equations of motion are reformulated into one decoupled governing equation in terms of transverse deflection (w) using the method of inverse differential operator. For the first time, an impermeability condition is developed that considers the moderately large deflection of the contact surface in order to correct the pressure distribution of fluid flow. Based on the potential flow theory, closed-form expressions of hydrodynamic pressure are obtained for different fluid boundary conditions including infinite depth of fluid, flow bounded by a rigid wall and flow between two identical elastic plates. Then, the Galerkin and multiple-scale perturbation methods are used to obtain closed-form solution of nonlinear natural frequency in terms of maximum vibration amplitude. Finally, case studies are presented to investigate the effects of geometric ratios, boundary condition, material distribution, layup, characteristics of flow and geometric nonlinearity on the response quantities. Findings indicate that the large deformation term in the developed impermeability condition has significant effect on the pressure distribution and its effect is more pronounced for thicker plates with larger mode number in the flow direction. Therefore, the novel nonlinear fluid-structure interaction model should be considered to study flow-induced dynamic behavior of sandwich plates with different boundary conditions. In addition, the snap-through behavior is seen in the nonlinear frequency-upstream speed curves and the incipient points of dynamic instability can vary remarkably with the fluid boundary conditions.

3DMASC: Accessible, explainable 3D point clouds classification. Application to bi-spectral topo-bathymetric lidar data

Three-dimensional data have become increasingly present in earth observation over the last decades. However, many 3D surveys are still underexploited due to the lack of accessible and explainable automatic classification methods, for example, new topo-bathymetric lidar data. In this work, we introduce explainable machine learning for 3D data classification using Multiple Attributes, Scales, and Clouds under 3DMASC, a new workflow. This workflow introduces multi-cloud classification through dual-cloud features, encrypting local spectral and geometrical ratios and differences. 3DMASC uses classical multi-scale descriptors adapted to all types of 3D point clouds and new ones based on their spatial variations. In this paper, we present the performances of 3DMASC for multi-class classification of topo-bathymetric lidar data in coastal and fluvial environments. We show how multivariate and embedded feature selection allows the building of optimized predictor sets of reduced complexity, and we identify features particularly relevant for coastal and riverine scene descriptions. Our results show the importance of dual-cloud features, lidar return-based attributes averaged over specific scales, and of statistics of dimensionality-based and spectral features. Additionally, they indicate that small to medium spherical neighbourhood diameters (<7 m) are sufficient to build effective classifiers, namely when combined with distance-to-ground or distance-to-water-surface features. Without using optional RGB information, and with a maximum of 37 descriptors, we obtain classification accuracies between 91 % for complex multi-class tasks and 98 % for lower-level processing using models trained on less than 2000 samples per class. Comparisons with classical point cloud classification methods show that 3DMASC features have a significantly improved descriptive power. Our contributions are made available through a plugin in the CloudCompare software, allowing non-specialist users to create classifiers for any type of 3D data characterized by 1 or 2 point clouds (airborne or terrestrial lidar, structure from motion), and two labelled topo-bathymetric lidar datasets, available on https://opentopography.org/.

Hierarchical Deployment of Vortex Generators for Wake Management in Finned-Tube Heat Exchanger

While developing thermal management systems, volumetric compactness of the heat exchange module is a critical design factor. This three-dimensional computational analysis seeks to boost the thermal compactness of fin-and-tube heat exchangers by employing winglet-type vortex generators. Due to the fact that the thermo-hydraulic performance of vortex generators in such thermal systems is determined by three distinct design parameters, namely the attack angle, spatial location, and geometric aspect ratio, a concurrent parametric analysis of all three design parameters is conducted to gain a thorough understanding. In addition, regression analysis is applied to develop functional correlations that can predict the enhanced thermo-hydraulic performance of the heat exchangers. The improvements in wake-affected heat transfer brought on by the modifications are also specifically explored, along with other aspects of the augmentation mechanism. The highest thermal augmentation over the wake-affected fin is seen as 120%. Based on a thermo-hydraulic tradeoff, the friction factor increases exponentially with the attack angle, and the rate of increase is lowest for 15–30 degree range of attack angle and highest for 45–60 degree range. Certainly, there are multiple locations where winglets can be erected, and heat transfer enhancement by each potential location incurs linearized increase in the friction factor.

Safety and pharmacokinetics of imaradenant (AZD4635) in Japanese patients with advanced solid malignancies: a phase I, open-label study

PurposeImaradenant is a novel potent and selective adenosine A2A receptor antagonist that is hypothesized to reduce immune suppression in the tumor microenvironment. This phase I, open-label, dose-escalation study evaluated the safety, pharmacokinetics, and anti-tumor activity of imaradenant.MethodsJapanese patients with advanced solid malignancies received imaradenant 50 mg (n = 3) or 75 mg (n = 7) once daily (QD). The primary objective was safety and tolerability, and the secondary objectives were pharmacokinetics and anti-tumor activity.ResultsThe median treatment duration was 2.10 months and 2.14 months for the 50- and 75-mg QD cohorts, respectively. The most common adverse events were nausea, malaise, decreased appetite, and vomiting. Five patients (50%) reported adverse events that were considered causally related to imaradenant; three patients had Grade 2 adverse events of malaise, nausea, and diarrhea. No deaths or serious adverse events occurred. The median times of maximum observed concentrations sampled after a single dose in the 50- and 75-mg QD cohorts were 1.08 h (range, 0.95–1.95) and 2.00 h (range, 0.92–5.52), respectively. There was little accumulation after multiple dosing, with geometric mean accumulation ratios of maximum concentration of 1.3 (50-mg QD) to 1.4 (75-mg QD) and area under the concentration–time curve 0–24 of 1.4 (50-mg QD) to 1.5 (75-mg QD). The best objective response was stable disease (3/10).ConclusionNo new or unexpected safety concerns were identified, and imaradenant had an acceptable safety profile at both 50- and 75-mg QD.ClinicalTrials.gov identifier NCT03980821 (June 10, 2019).

Free vibration analysis of sandwich structure via point interpolation meshfree method based on polynomial basic function

The stability of circular and annular sector plate structures under aerodynamic pressure in supersonic conditions is crucial for aircraft components. Conventional uniform materials lead to heavy structures, which are undesirable for aircraft. This study explores the use of functionally graded materials to enhance flutter stability. It employs a refined logarithmic shear deformation theory to describe plate displacement, classical elasticity theory for constitutive equations, and Hamilton’s principle for equations of motion. Two methods, finite element, and Meshfree radial point interpolation, are used to solve these equations and verify the results. Parameter studies are conducted to assess the effects of grading index, Biot’s coefficient, span angle, and geometrical aspect ratio, revealing unexpected adverse effects of grading material on stability.

A Randomized, Single-Dose, Parallel-Controlled Phase 1 Clinical Comparison of an Omalizumab Biosimilar Candidate with Reference Omalizumab in Healthy Chinese Male Volunteers.

This study evaluated the bioequivalence of omalizumab, a humanized monoclonal antibody against immunoglobulin-E (IgE), with one of its biosimilar candidates. The study was designed as a randomized, double-blind, parallel-controlled trial. A total of subjects who met the inclusion criteria and did not meet the exclusion criteria were dynamically randomly assigned to receive the test drug or the reference drug with a single subcutaneous injection of 150mg by the minimization method. The test group and the reference group had similar demographic characteristics and baseline characteristics of total IgE. The 90% confidence interval of the geometric average ratio of the area under the serum concentration-time curve from the time 0 to the time of last quantifiable concentration, the area under the serum concentration curve from time 0 to infinity, and the maximum observed serum concentration between the 2 groups were within 80%-125%, showing bioequivalence. The changing trend of total and free IgE in the 2 groups was similar after administration, proving the pharmacodynamic similarity. The 2 groups had no significant difference in the positive rate of antidrug antibodies, and the total positive rate of neutralizing antibodies was 0. The incidence of treatment-emergent adverse events and treatment-related adverse events were similar between the 2 groups, with no serious adverse events. This study shows that the test drug had similar pharmacokinetics, immunogenicity, and safety to the reference omalizumab in healthy male subjects.

On the nonlinear dynamics of a multi-scale flexoelectric cylindrical shell

The flexoelectric property shows the relationship between the strain gradient and the electric polarization and has a significant effect on static and dynamic responses of structures at small scales such as micro and nano. Nowadays, experimental studies for intelligent/composite ultra-small mechanical systems are complex, challenging, and in most cases still impossible, especially for nonlinear dynamic behavior analysis. For the first time, this study presents an advanced and complex generalized model for the nonlinear vibrations of a piezo-flexoelectric mechanical system based on a cylindrical shell. It should be noted, that the formulated boundary value problem is generalized, well-posed, and can be applied to the system at micro and nano scales. Hamilton's variational principle as well as assumptions of the first-order shear deformation theory (FSDT) and reformulated flexoelectric theory were used to derive equations of motion of the multi-scale intelligent shell system. To introduce nonlinear effects, von-Kármán strains are applied. Appropriate classical and non-classical mechanical/electric boundary conditions as well as higher-order forces and moments are determined to fully close the formulated problem. The Galerkin method combined with the GDQM, supported by the displacement control strategy and the weighted residual method, have been used to discretize and solve the nonlinear governing equations of the shell with different boundary conditions. Good convergence between the current results and the results from previous studies for simpler cases of the shell was proved. Furthermore, the results showed that geometric ratios of the structure, gradation of material properties, thickness of the flexoelectric layers, and the size effect parameter significantly influence the nonlinear frequency of the structure under the direct flexoelectric effect.

Immunogenicity and safety of heterologous versus homologous prime-boost schedules with inactivated and adenoviral vectored SARS-CoV-2 vaccines – A prospective multi-center study

BackgroundDuring the peak of Coronavirus disease (COVID-19) pandemic in Thailand when the emergence of delta variant reduced the efficacy of inactivated vaccine, Thailand had abundance of inactivated vaccine but mRNA vaccine was not available and the supply of adenoviral-vectored vaccine was limited. The heterologous vaccination using CoronaVac and ChAdOx1-nCoV-19 vaccines was applied. We aim to compare the immunogenicity of immune response of primary vaccination with homologous ChAdOx1 nCoV-19 and heterologous vaccination with CoronaVac and ChAdOx1 nCoV-19. MethodsA total of 430 adults, scheduled to receive ChAdOx1-nCoV-19 as their second dose of primary COVID-19 vaccination, were enrolled. Participants were classified into two groups based on the first dose vaccine as CoronaVac (heterologous group) or ChAdOx1 nCoV-19 (homologous group). The primary outcome was antibodies to the SARS-CoV-2 spike protein receptor binding domain (anti-RBD) titres at 28 days after the second dose of vaccination. Secondary outcomes were anti-RBD titres at 90 days, surrogate viral neutralizing test (sVNT) at 28 and 90 days, and adverse events. FindingsIn 358 participants with correct vaccine interval, the anti-RBD geometric mean titre ratio for the heterologous versus homologous group was 0.55 (95%CI; 0.44–0.067); p < 0.001 at day 28, and 0.80 (95%CI; 0.65–1.00); P = 0.05 at day 90. Median sVNT neutralizing activity was not significantly different in the heterologous versus homologous group at 28 days (93.5 vs 92.7 %); p = 0.13, but significantly higher in the heterologous group at day 90 (82.9 vs 76.4 %); p = 0.01. InterpretationThe homologous vaccination resulted in higher anti-RBD titres at 28 days after vaccination, but titres in the homologous group showed more rapid decline at 90 days. In the sVNT assay, median neutralization was similar at 28 days, but was longer-lasting and higher in the heterologous group at 90 days. FundingThis research received funding from the Royal College of Physicians of Thailand special grant 2021 for research initiative during COVID-19 pandemic.

Design Parameters for Geotextile-Reinforced Unpaved Road by Applying Dimensional Analysis

Abstract Soil swelling in road layer is the complex phenomenon. The paper aims to derive a concise expression for two challenging design parameters when the subgrade layer is expansive in geotextile-reinforced unpaved road. The design parameters considered in the present study are the mobilized bearing capacity and swelling pressure for expansive soil. Herein the dimensional analysis via Buckingham’s π method is applied to derive the design parameters by forming the dimensionless group for prototype and model system. The model testing for the swelling pressure and mobilized bearing capacity are carried out in the laboratory by using consolidometer ring and CBR set up. The test results reveal the swelling pressure of 22.03kN/m2 for the soil sample having 76% as degree of saturation. A linear relation is observed between swelling pressure and degree of saturation and becomes equal upon surcharge. The mobilized bearing capacity for the expansive soil sample is 0.47kg/cm2. The failure pattern observed during testing is general shear failure in unsoaked condition and punching soil failure in soaked condition. The paper provides geometric ratio of 1:6 for model and prototype and also suggests modification in Giroud and Han generic equation by including the developed dimensionless group.

Flexural rigidity of pressurized model notochords in regular packing patterns

The biomechanics of embryonic notochords are studied using an elastic membrane model. An initial study varying internal pressure and stiffness ratio determines tension and geometric ratios as a function of internal pressure, membrane stiffness ratio, and cell packing pattern. A subsequent three-point bending study determines flexural rigidity as a function of internal pressure, configuration, and orientation. Flexural rigidity is found to be independent of membrane stiffness ratio. Controlling for number and volume of cells and their internal pressure, the eccentric staircase pattern of cell packing has more than double the flexural rigidity of the radially symmetric bamboo pattern. Moreover, the eccentric staircase pattern is found to be more than twice as stiff in lateral bending than in dorsoventral bending. This suggests a mechanical advantage to the eccentric WT staircase pattern of the embryonic notochord, over patterns with round cross-section.

Location and Extents of Scour Hole around an Erodible Spill-through Abutment under Clear Water Condition and the Abutment Classification

Bridge abutment scour is a complex phenomenon, which significantly affects bridge stability and is responsible for the damage and failures of many bridges over waterways across the world. Given the widespread and devastating human and societal costs, numerous experimental studies have been conducted to find the mechanisms of bridge abutment scour, and several empirical and mathematical prediction models are available. However, the location of the scour hole and its extents have not been investigated in detail, which is one of the important parameters, not only for the bridge stability itself, but also for the safety of structures around the bridge and their design. Thus, in this study, laboratory experiments were carried out using several different lengths of erodible abutment under different flow conditions to suggest a new mathematical criterion for abutment classification with respect to the location of scour holes. Furthermore, additional analysis was conducted to locate the point of the deepest scour depth and extent of the scour hole around the abutment. Both in transverse and flow direction, the location of the scour hole and the point of the deepest scour are governed by the geometric contraction ratio. This research will be useful in analyzing the bridge safety itself as well as safety of the river training works close to the bridge with respect to the location and extents of the scour hole.

Oral Decitabine/Cedazuridine Vs Intravenous Decitabine for Acute Myeloid Leukemia: Final Results of a Randomized, Crossover, Registration-Enabling, Pharmacokinetics Study

Background: Parenterally administered hypomethylating agents (HMAs), decitabine (DEC) and azacitidine (AZA), are approved in Europe for adult patients with acute myeloid leukemia (AML) who are not candidates for standard induction chemotherapy as single agent or in combination with venetoclax. Cedazuridine(C) is a novel, potent, and safe inhibitor of cytidine deaminase (CDA) and when given in combination with decitabine, cedazuridine enables efficient oral availability of decitabine.ASTX727 (DEC-C) is a fixed-dose combination (FDC) tablet of 35 mg DEC and 100 mg cedazuridine, DEC-C has been approved for MDS in the US, Canada, and Australia. Here we present final results using DEC-C in an AML population appropriate for single-agent decitabine treatment. Aims: Describe the final clinical outcomes of patients with AML with additional analysis of genetic profiles. Methods: The ASCERTAIN study used a randomized two-period, two-sequence, two-treatment, crossover study design. Patients were randomized 1:1 to either Sequence A: DEC-C (35 mg DEC/100 mg cedazuridine) in Cycle 1 followed by IV-DEC at 20 mg/m 2 in Cycle 2, or Sequence B: receiving IV-DEC in Cycle 1 followed by DEC-C on Cycle 2 to compare pharmacokinetics (PK) [primary endpoint Area Under the Curve (AUC) equivalence over 5 days of dosing]. All patients received DEC-C from Cycle 3 until treatment discontinuation to assess safety and clinical efficacy. Patients were eligible as per the EMA-approved decitabine label (newly diagnosed AML who are not candidates for standard induction chemotherapy). Clinical responses were assessed according to modified International Working Group (IWG) 2003 response criteria. Pre-treatment peripheral blood was used for DNA isolation from leukocytes, and molecular abnormalities identified using a NGS hematologic malignancy panel. Cox-regression analysis on the various factors (eg binary mutational status, CR, etc.) was used for analyses of risk-factors for overall survival (OS). Results: 89 patients were randomized, of whom 87 were treated. The median age of patients was 78.0 years (range, 61 to 92) with 31 (35.6%) males and 56 (64.4%) females. Cytogenetic risk classification was poor-risk in 33 (37.9%), intermediate-risk in 45 (51.7%), and 9 (10.4%) not evaluated patients. For the primary endpoint, preliminary PK data was available from 69 patients who successfully completed PK assessments for both IV-DEC and DEC-C cycles, and the DEC AUC 0-24 (h*ng/mL) 5-Day geometric mean estimate was 904 for DEC-C and 907 for IV-DEC resulting in an oral/IV geometric LSM AUC ratio of 99.64% (90% CI of 91.23-108.8%). Safety findings were consistent with those anticipated for IV-DEC (related Grade ≥ 3 AEs in more than 10% were thrombocytopenia, neutropenia, anaemia, and febrile neutropenia). As of the database lock (25May2023), median follow up was 24.5 (20.2, 25.0) months (25% of 19.7 and 75% of 25.2 months). The best response was complete response (CR) in 19/87 (21.8%, 95% CI: 13.7, 32.0%); CR with incomplete blood cell count recovery (CRi) in 5 patients (5.7%); and CR with incomplete platelet recovery (CRp) in 2 (2.3%); resulting in composite response rate [CR + CRi] of 27.6%. The median overall survival was approximately 8.9 months (95% CI: 6.0, 13.1).These results obtained with DEC-C are consistent with those observed for IV-DEC. Multiple genes, including ASXL1, TP53, RUNX1, and SRSF2 genes were present in more than 20% of the AML patients. TP53 mutation was associated with worse survival. Summary/Conclusion: This randomized phase 3 study in AML patients not candidates for standard induction chemotherapy demonstrates that Daily X 5 dosing of the oral FDC of DEC-C resulted in an equivalent DEC AUC exposure to IV-DEC at 20 mg/m 2 over 5 days. Pharmacodynamic data showed similar demethylation rates (≤1.1% difference). In addition, safety findings and observed clinical activity (response rates and OS) are consistent with published data from IV-DEC, suggesting that DEC-C has the potential to be an oral alternative to the standard IV-DEC Daily×5 regimen. These findings support the use of DEC-C in patients with AML who are not candidates for standard induction chemotherapy.

Efficiency improvement investigation through Miller cycle strategy for SI engine operating on stoichiometric producer gas and methane blends

Decentralized power generation through gasifier-engine system is an attractive alternative for reducing environmental impact and power grid dependency. For effective sewage sludge-waste to end-use electricity generation by engine integration, this work aims to simulate and investigate thermal efficiency enhancement in SI engine by employing late inlet valve close (LIVC) strategy with 12.0:1 geometrical compression ratio miller cycle and operating engine with sewage sludge-based producer gas (SSPG) by blending methane in various proportions. A quasi-dimensional thermodynamic model is simulated to explore SI engine performance, after validation from an experimental reference. Effects of blending SSPG to methane, varying LIVC and spark timing were analyzed respective to indicated thermal efficiency (ITE), indicated power (IP), brake thermal efficiency (BTE), brake power (BP), brake-specific energy consumption (BSEC) and emissions (CO and NO). Parametric results were found in trade-off nature of performance corresponding to engine efficiency and power. Thus, response surface methodology (RSM) was applied to find the best operating conditions for enhancing performance and diminishing emissions of the blended fuel SI engine. 64.7 % SSPG Blend, 70.33⁰ (ABDC) LIVC, and 34.03⁰ (BTDC) SOI were found as optimum operating parameters corresponding to the generated optimal responses of 35.47 % ITE, 5.18 kW IP, 27.95 % BTE, 4.08 kW BP, 12.671 MJ/kWh BSEC, and 0.688 V% CO, 1456.93 ppm NO emissions. The ANOVA-based regression model shows composite desirability of 0.8 with 95 % confidence level. In summary, the optimization method and optimal operation parameters offer significant reference for improving engine performance for high CR miller cycle-based LIVC approach.

Immunogenicity and Safety of Heterologous Omicron BA.1 and Bivalent SARS-CoV-2 Recombinant Spike Protein Booster Vaccines: A Phase 3 Randomized Clinical Trial.

Mutations present in emerging SARS-CoV-2 variants permit evasion of neutralization with prototype vaccines. A novel Omicron BA.1 subvariant-specific vaccine (NVX-CoV2515) was tested alone or as a bivalent preparation with the prototype vaccine (NVX-CoV2373) to assess antibody responses to SARS-CoV-2. Participants aged 18 to 64 years immunized with 3 doses of prototype mRNA vaccines were randomized 1:1:1 to receive a single dose of NVX-CoV2515, NVX-CoV2373, or the bivalent mixture in a phase 3 study investigating heterologous boosting with SARS-CoV-2 recombinant spike protein vaccines. Immunogenicity was measured 14 and 28 days after vaccination for the SARS-CoV-2 Omicron BA.1 sublineage and ancestral strain. Safety profiles of vaccines were assessed. Of participants who received trial vaccine (N = 829), those administered NVX-CoV2515 (n = 286) demonstrated a superior neutralizing antibody response to BA.1 vs NVX-CoV2373 (n = 274) at day 14 (geometric mean titer ratio, 1.6; 95% CI, 1.33-2.03). Seroresponse rates were 73.4% (91/124; 95% CI, 64.7-80.9) for NVX-CoV2515 vs 50.9% (59/116; 95% CI, 41.4-60.3) for NVX-CoV2373. All formulations were similarly well tolerated. NVX-CoV2515 elicited a superior neutralizing antibody response against the Omicron BA.1 subvariant as compared with NVX-CoV2373 when administered as a fourth dose. Safety data were consistent with the established safety profile of NVX-CoV2373. ClinicalTrials.gov (NCT05372588).

Self-weight and thermal bifurcation analysis of functionally graded vertical annular plates

The present paper thoroughly investigates the influence of structural weight on the thermal buckling of standing circular and annular plates. The structure is composed of symmetrically functionally graded materials (FGM) in terms of its thickness. The first-order theory of shear deformation along with nonlinear strain–displacement equations has been employed to derive the governing equations of the FG plate. First, the asymmetric pre-buckling path of the structure under the influence of weight and heat is calculated by a semi-analytical method. The plate's stability relations are extracted using the adjacent equilibrium criterion and virtual work principle. Then, the stability equations are analyzed by the 2D generalized differential quadrature (GDQ) method. Parametric results are presented based on the analysis of the FGM power-law index, geometric ratios, and edge constraints on the buckling of the vertical plate. The study reveals the critical power-law index and thickness at which the structure becomes unstable, shedding light on the previously neglected calculation of weight-induced buckling in vertical structures. Also, the effect of weight on the buckling mode shapes of heavy plates and disturbing its symmetry is demonstrated. Additionally, this study presents the first investigation into the effect of weight on the thermal stability of annular FG plates.

Thermal behavior of composite phase change material of polyethylene in a shell and coil-based thermal energy storage: Numerical analysis

Energy management and environmental sustainability are important concerns across the world at present. In that context, using recycled waste material such as polyethylene as a phase change material (PCM) in a latent heat storage (LHS) system fulfils both motives. However, effective energy conversion requires proper design of thermal energy storage (TES) and improvement of thermophysical properties of the working material. In the present numerical analysis, a shell and coil-based TES is considered with linear low-density polyethylene (LLDP) as base material to be compounded with functionalized graphene in three different concentrations such as 1 %, 3 %, and 5 %, called composite phase change material i.e., CPCM1, CPCM2, and CPCM3 respectively. The diameter ratio between the coil and shell of TES, termed the geometrical ratio (Gr) is taken as 0.3, 0.5, and 0.7 in the analysis, whereas the coil's pitch length (pc) is varied from 10 mm to 30 mm. The orientation of TES is also varied from horizontal (0°) to vertical position (90°) with an interval of 30° inclination. Results reveal that the charging time for the complete liquefaction of storage material decreases a maximum of 65 % in the case of CPCM 3 with 5 % graphene. Increasing the heat supply from 125 W to 250 W sharply decreases the charging time, however, further increasing heat power affects moderately. The charging time gradually decreases to 56 % and 54 % in the case of LLDP and CPCM 2 respectively as Gr increases from 0.3 to 0.7 in both cases. The pitch length effect on the thermal performance of TES is found to be negligible. The analysis shows that the horizontal position of TES accrues the lowest charging time for the thorough melting of PCM.

Divided Exhaust Period Assessment for Fuel-Enrichment Reduction in Turbocharged Spark-Ignition Engines

&lt;div&gt;Turbocharged spark-ignition (SI) engines, owing to frequent engine knocking events, utilize retarded spark timing that causes combustion inefficiency, and high turbine inlet temperature (Trb-In T) levels. Fuel enrichment is implemented at high power levels to prevent excessive Trb-In T levels, resulting in an additional fueling penalty and higher CO emissions. In current times, fuel-enrichment reductions are of high strategic importance for engine manufacturers to meet the imminent emissions regulations. To that end, the authors investigated the divided exhaust period (DEP) concept in a 2.2 L turbocharged SI engine with a geometric compression ratio of 14 by decoupling blowdown (BD) and scavenge (SC) events during the exhaust process. Using a validated 1D engine model, the authors first analyzed the DEP concept in terms of pumping mean effective pressure (PMEP) and engine knocking (KI) reduction. Subsequently, the authors examined the effectiveness of the DEP concept using a “low-restriction exhaust flowpath” and varying late intake valve closing (LIVC) duration.&lt;/div&gt; &lt;div&gt;First, using DEP, significant PMEP and KI reductions benefits were observed at high power engine conditions along with a large increase in Trb-In T from the early blowdown event. Subsequently, use of a low restriction exhaust flowpath and a shortened LIVC duration further elevated the DEP benefits, including Trb-In T reduction that facilitated enrichment reduction. At 4,000 RPM/20 bar BMEP, ~70% lower PMEP and a 2.2 point increase in ITEg were noted relative to the base engine. However, the 2,000 RPM peak torque engine condition was compromised using DEP, due to knock limitation and deteriorated stock turbocharger performance. Finally, DEP design integrated with an off-the-shelf (new) turbocharger system remedied the low-end torque challenges and demonstrated a notable enrichment reduction and thermal efficiency benefits at the full load engine curve including the 200 kW rated condition.&lt;/div&gt;

Electro-Mechanical Buckling of Shallow Segments of Functionally Graded Porous Toroidal Shell Covered by Piezoelectric Actuators

The current work deals with the mechanical buckling behavior of saturated porous toroidal shell segments sandwiched by piezoelectric actuator layers. Material properties of the porous shells with nonuniform distributed porosities are assumed to vary as a specific function of the thickness and porosity parameters. The nonlinear equations of the sandwich toroidal shell having either positive or negative Gaussian curvature are obtained on the basis of Biot’s poroelasticity theory. The energy method as the minimum potential energy principle is applied to derive the governing equations of the sandwich shells. The buckling equations of the piezo-porous sandwich shells under various types of mechanical loading are established by employing the adjacent equilibrium criterion. The governing equations as a set of the coupled partial differential equations are solved using an analytical method including the Airy stress function. Closed-form solutions are derived for shallow segments of the sandwich toroidal shell with positive/negative Gaussian curvature under lateral pressure, axial compression, and hydrostatic pressure loadings. Novel numerical results are presented in this work to show the effects of important factors such as the piezoelectric layer thickness, applied voltage, shell geometrical ratio, and variation of the porosity coefficient on the buckling behavior of these structures.

Nanoform of Phospholipid Composition: Investigation of the Morphological Features by Atomic Force Microscopy.

Morphological features of the nanoform of a phospholipid composition (NFPh), which can be used as an individual pharmaceutic agent or as a platform for designing drug delivery systems, have been studied using atomic force microscopy (AFM). NFPh has been developed, and its characteristics have been investigated using conventional drug analysis methods, including the determination of the mean diameter of nanosized vesicles in the emulsion via dynamic light scattering (DLS). Using DLS, the mean diameter of the vesicles was found to be ~20 nm. AFM imaging of the surface has revealed four types of objects related to NFPh: (1) compact objects; (2) layer fragments; (3) lamellar structures; and (4) combined objects containing the compact and extended parts. For type (4) objects, it has been found that the geometric ratio of the volume of the convex part to the total area of the entire object is constant. It has been proposed that these objects formed owing to fusion of vesicles of the same size (with the same surface-to-volume ratio). It has been shown that this is possible for vesicles with diameters of 20 nm. This diameter is in good coincidence with the value obtained using DLS.