Search

Sandstorms have destructive effects on railway infrastructures due to the movement and erosion of sand. One of the proposed solutions to reduce the impact of windblown sand on desert railways is the hump slab track superstructure. This system entails removing the ballast layer and elevating the rails using concrete foundations called humps, which create sand movement channels beneath the rails. The hump's geometry must not only meet optimal aerodynamic conditions but also ensure ample clearance for sand passage, maintaining structural stability and efficient railway performance. In this study, the aerodynamic evaluation of various hump geometry is examined considering the elliptical (EL) and semicircular-rectangular (CR) shapes. Simulations are carried out using 3D computational fluid dynamics in ANSYS Fluent software. A gas–solid two-phase model, comprising a distinct phase for sand particles and another for air, is developed to assess the sand movement capacity through the selected hump geometries. A wind tunnel experiment is then performed on a prototype of a hump slab track to validate the software model. The findings highlighted that the CR shape, with a height of 25 cm, resulted in the most favorable outputs. [ABSTRACT FROM AUTHOR]

Efficient aerodynamics significantly impact your vehicle's overall efficiency. Enhancing vehicle performance and fuel economy hinges on optimizing aerodynamics. Reduced drag equates to decreased resistance against air, requiring less energy for propulsion. This study employs numerical investigation utilizing ANSYS Fluent computational fluid dynamics (CFD) simulations to identify the aerodynamic characteristics of an SUV. The goal is to gain insights into the vehicle's aerodynamics. This study involves the creation of a 3D model of the SUV car, which is then subjected to simulated wind channel testing. ANSYS Fluent is employed to simulate the airflow around the car, enabling the estimation of drag and lift forces. The primary objective of the study is to achieve an optimal shape design for the SUV by varying the glass inclination angle within the range of 145° to 160°, and subsequently observe its effects. It has been observed that as the glass inclination angle increases, both drag and lift forces decrease gradually, with optimal results observed at a 160° inclination angle. Additionally, detailed observations of pressure and velocity fluctuations were made to further analyze flow phenomena. Adjusting the angle could potentially modify airflow around the vehicle, potentially minimizing drag by facilitating smooth airflow over the car, thus reducing resistance. [ABSTRACT FROM AUTHOR]

Rapid compression machines (RCM) are well-known tools to study the autoignition phenomenon under engine-relevant conditions. Covering a wide range of pressure and temperature at the top dead center (TDC), it can be employed with different types of mixtures and thermal stratification. Creating a homogeneous hot core region after compression in the combustion chamber is one of the challenges to overcome for RCM studies. The objective of the present work is to characterize from aerodynamic and thermal points of view a new configuration in the optical RCM of Pprime Institute. The latter aims at ensuring a wider adiabatic core region in terms of time and space through the installation of a creviced piston, specifically adapted to the square cross-section cylinder of this particular RCM. For this purpose, the internal flow has been qualified using high-frequency Particle Image Velocimetry with different laser sheet locations. Temperature variation during and after compression is measured at several positions with respect to the cylinder head, using thermocouples with wire diameter of 7.6 µm. It is observed that the piston cavity is able to collect the boundary layer created during compression and maintain a wide region at low velocity after the top dead center. Furthermore, it is demonstrated that different temperature gradient values can be generated and quantified within the adiabatic core region through differential heating of the chamber. This feature is promising for future works devoted to the analysis of combustion regimes. More generally, the thin wire thermocouples are shown to be accurate and reliable sensors to measure temperature in severe and transient pressure and temperature conditions specific to RCM internal flows. [ABSTRACT FROM AUTHOR]

Structural defects in graphene are inevitable during the production process, which have remarkable impacts on the mechanical properties of graphene and further affect the properties of nanocomposite reinforced by graphene. In this work, a bottom-up multiscale approach is employed to investigate the nonlinear dynamics of defective graphene reinforced composite plates from the material properties of nanocomposites to the dynamic behavior of macro-composite plates. The molecular modeling and simulation are conducted by molecular dynamics (MD) to evaluate the effective mechanical properties of pristine graphene, vacancy defective graphene, Stone–Wales defective graphene, poly (methyl methacrylate) (PMMA) and graphene/PMMA composites reinforced by different graphene configurations at the nano-scale. Meanwhile, the fracture mechanism and interfacial interaction energy between graphene and PMMA matrix during the deformation process are examined to explore the enhancement mechanism of nanocomposites. The efficiency parameters are derived by incorporating the MD results and the extended Halpin–Tsai micromechanics model to capture the heterogeneity of nanocomposite at the nano-scale as well as the continuum scale, and then the effective material properties considering the effect of defect, temperature and pressure are substituted into the nonlinear dynamics of functionally graded graphene reinforced composite (FG-GRC) plates at the macro-scale. The governing equations of motion for FG-GRC plates under the aerodynamic pressure are derived based on the third-order shear deformation theory, von-Karman nonlinear strain–displacement relation and Hamilton's principle. The aerodynamic pressure acting on the surface of the plate consists of two parts, one is the static pressure, and the other is the disturbed air flow. Furthermore, Galerkin method and the fourth-order Runge–Kutta method are exploited to discrete and solve the governing equations of motion. The bifurcation, time history and phase diagrams of FG-GRC plates are obtained to analyze the dynamic characteristics of the plates. This study reveals the nonlinear dynamic characteristics of graphene/PMMA composite plate, which contributes to the prediction of dynamic response of composite structure in the aerospace field. [ABSTRACT FROM AUTHOR]

For golfers, the length of the flight distance is very important for improving scores. Therefore, the surface of a golf ball is provided with innumerable dents called dimples to improve the flight distance. These dimples can be characterized by the dimple occupancy and dimple volume ratio. Therefore, we manufactured model balls in which the dimple occupancy was changed by the dimple diameter and the number of dimples, and the dimple depth was changed to change the dimple volume ratio. Fifteen model balls were designed using 3D CAD and then 3D printed. Using these balls, we carried out lift and drag measurements in wind tunnel experiments. Then, a flight trajectory simulation was performed based on the obtained experimental results, and the effects of the dimple occupancy and dimple volume ratio on the flight distance were elucidated. In rotating golf balls, when the dimple depth was shallow, i.e., D/d = 4.55 × 10–3, and the occupancy ratio was 80% or higher, the lift-drag ratio was higher, and the flying distance was increased. However, when the dimple depths were D/d = 6.82 × 10–3 and D/d = 9.09 × 10–3, there was almost no effect of the occupancy ratio. Furthermore, when comparing these two depths, the lift-drag ratio was bout 15% lower for deeper dimples. With respect to the dimple volume ratio, the drag coefficient increased with increasing dimple volume ratio. The lift-drag ratio was also highest in the dimple volume ratio range of 11.0–12.0 × 10–3. [ABSTRACT FROM AUTHOR]

Long term operation of space stations provides valuable opportunities for space science experiments. These space products and samples need to be fully evaluated on the ground. Although SHENZHOU and TIANZHOU manned spacecraft can carry these samples, their capacities are limited to 50 kg for each time, which limits the development of space scientific experiments. This paper investigates the aerodynamic deceleration of ultra-large deployable heat-resistant structures for efficient descending of space station payload. The ultra-large deployable heat-resistant structure was designed and modeled. The flow fields in the supersonic flow under different Mach numbers and angles of attack were simulated and aerodynamic forces were analyzed with the computational fluid dynamics (CFD) method. The results demonstrate that large vortexes were produced on the back of the aircraft due to the viscosity. With the increase of Mach number, the compressibility effect of airflow is more significant. The increase in the angle of attack leads to the change of the position of the stagnation point of the spacecraft. Moreover, the static analysis of the aeroshell and unfolding structure was carried out to guarantee the safety of the spacecraft. The proposed aerodynamic deceleration technology is an efficient and low-cost scientific approach to deliver high-mass payloads for space scientific experiments, which will advance the development of supporting technologies for space sciences. [ABSTRACT FROM AUTHOR]

Owing to the excellent mechanical properties, polymethyl methacrylate (PMMA)/carbon nanotube (CNT) composite has been increasingly adopted in the aerospace field, which is usually subjected to various temperature conditions and supersonic aerodynamic loads. Using a molecular dynamics (MD)-based multiscale simulation, the nonlinear forced vibration of PMMA/CNT composite plate is investigated under coupled temperature and aerodynamic load conditions. The longitudinal, transverse and shear moduli of PMMA/single-walled CNT (SWCNT) nanocomposite obtained from MD simulation at different temperature and pressure levels are substituted into the extended rule of mixtures to establish the constitutive equations of PMMA/CNT composite plate. Meanwhile, Poisson's ratio and thermal expansion coefficient of nanocomposite are used in the constitutive equations. Based on the third-order shear deformation theory, von Karman nonlinear strain–displacement relation and Hamilton's principle, the partial differential equation of composite plate is derived, which is reduced into a set of coupled ordinary differential equations by applying Galerkin method and is solved using the fourth-order Runge–Kutta method. The bifurcation diagrams, phase portraits, time histories and Poincare maps of composite plate are obtained under the complex loads including transverse harmonic excitation and aerodynamic pressure, which are applied to analyze the dynamic characteristics of system. This study reveals the nonlinear dynamic characteristics of PMMA/CNT composite plate, which contributes to the prediction of long-term performance of composite materials in aerospace field. [ABSTRACT FROM AUTHOR]

The European project RETALT (Retro Propulsion Assisted Landing Technologies), funded by the Horizon 2020 framework program (Grant agreement No 821890), has as main objective to investigate critical technologies for the assisted descent and landing of re-usable first stages. Among these technologies, one can find aerodynamics, aerothermodynamics, flight dynamics, guidance navigation and control (GNC), Structures, mechanisms, thrust vector control (TVC) and thermal protection systems (TPS). The present paper focuses in particularly on the aerodynamics technology applied to a vertical landing launcher configuration, called RETALT1, including retro-propulsion. During the landing phase of the first stage of the launcher, the main devices for control and trim of the vehicle (besides the retro-propulsion) are the aerodynamic control surfaces (ACS). Three types of aerodynamic control surfaces are investigated by means of numerical computations, using the NSMB (Navier Stokes Multi Block) CFD code. The control surfaces considered are the deployable interstage segments (also named petals), grid fins and planar fins. Aerodynamic coefficients as well as forces acting on the control surfaces are extracted from the CFD computations to assess the efficiency of each type of devices and to populate the Aerodynamic Database (AEDB) for flight dynamic analysis. [ABSTRACT FROM AUTHOR]

With the ongoing changes in the modern world, the usage of renewable energy sources is increasing. The negative impact of fossil fuels on global warming has led to the search for clean energy sources. Wind energy, which is the most widely used of those sources, is discussed in this study. Numerous studies have been undertaken in this regard, but seismic effects are only newly being considered. In addition to having strong wind zones, Turkey is located in a geographical position through which active fault lines pass. The presence of high wind zones overlapping with these fault lines necessitates seismic analysis for turbines planned to be built in the country. Analysis of wind and seismic load simulation is difficult with traditional structural design programs. In this study, coefficients including wind loads are suggested for civil engineers who plan to analyze wind turbines with only seismic effects. For this purpose, a horizontal axis steel wind turbine with a 5 MW scale is analyzed in this work considering a series of wind and seismic loads in the area around Gelibolu. These environmental effects are evaluated under different operating conditions of the turbine, including normal operation with no earthquake loads, park condition with earthquake loads, idling condition with wind loads, normal operation with earthquake loads, and idling condition with earthquake and wind loads. The full system model of the turbine is developed with the FAST finite element program employing a special code for wind turbines developed by the National Renewable Energy Laboratory. As a result of the analysis, it is concluded that seismic loads acting with the wind significantly change the internal forces. Damping effects occur when seismic and wind loads act at the same time. For this reason, wind loads need to be reduced by a certain coefficient in some cases. Coefficients are proposed here for application in initial designs and load combinations for certain wind and earthquake conditions. [ABSTRACT FROM AUTHOR]

To explore the influence of the traveling wave parameters on the aerodynamic characteristics of Ahmed models, the geometric model of the traveling wave wall is used as the study object, and the influence of the traveling wave geometric parameters on aerodynamic drag is studied by numerical simulation. A cosine-type traveling wave digital model is established on the basis of Ahmed's original model. Results show that the static traveling wave structure can play a good role in reducing drag under some driving conditions. The traveling wave's drag reduction characteristics are affected by the layout position, depth, wavelength, and other related parameters and more affected by driving speed. Finally, a group of working conditions with good drag reduction effects is selected, and the principle of drag reduction by using static traveling wave structure is explained qualitatively and quantitatively through velocity field, shear stress, and pressure field. [ABSTRACT FROM AUTHOR]

A scaled model of the X38-like configuration was simulated under hypersonic conditions for the direct simulation Monte Carlo method and the unified gas kinetic scheme. The inflow conditions considered several flow regimes, from the near-continuum through the slip-transitional to the free molecular regime. Flow fields and surface properties were compared in detail between these two methods. Not only the density and temperature contours distribution but also the surface pressure, heat flux, friction distribution, both kinetic methods give fairly consistent results. Aerodynamics of the model were also achieved and compared. The results provided by both methods agreed with each other very well. The effects of the Knudsen number and angle of attack were assessed. It is meaningful to carry out comparative studies and accelerate both methods to further progress. [ABSTRACT FROM AUTHOR]

Mining generates a significant quantity of waste material including ballast, gravel, and slags, which are often deposited in areas without taking into account the environment impacts and the need to ensure the physical and chemical stability of the disposed waste. One of the less studied problems is the emission of particulate matter produced by wind erosion at the dumpsites. This erosion is mainly caused by two factors, wind speed and turbulence, due to surface phenomenon. Until now, the design of waste dumpsites in the Chilean mining industry has not considered these environmental conditions. Efforts to minimize disposal costs have always been achieved by depositing ballast without considering these variables. When wind impacts this unprotected surface, it creates a source of dust that requires some special attention. The problem that this research tries to solve is to reduce particulate material to the atmosphere from waste dumps in which, under certain atmospherics and geographic conditions, specifically on winter season, its concentrations overpass the maximum limit allowed by law, generating bronchopulmonary diseases and even closing partially or totally mine operation. The result is the creation of a waste dumpsite design model, with its corresponding algorithms, which will allow optimization of the waste dumpsite design. From these results, future researches could explore more sustainable mining, such as unit operations, drilling, blasting, load and crushing material, reducing particulate material emissions to the atmosphere, and minimizing environmental impact due to exploitation. [ABSTRACT FROM AUTHOR]

Fluid-structure interaction (FSI) problems play an important role in many technical applications, for instance, wind turbines, aircraft, injection systems, or pumps. Thus, the optimization of such kind of problems is of high practical importance. Optimization algorithms aim to find the best values for a system's parameters under various conditions. In this paper, we present a new Backtracking Search Optimization Algorithm for multiobjective optimization, named BSAMO, a new evolutionary algorithm (EA) for solving real-valued numerical optimization problems. EAs are popular stochastic search algorithms that are widely used to solve nonlinear, nondifferentiable and complex numerical optimization problems. In order to test the performance of this algorithm, a well known benchmark multiobjective problem has been chosen from the literature, and for FSI optimization, using a partitioned coupling procedure. The method has been tested through a 2D plate and a 3D wing subjected to aerodynamic loads. The obtained Pareto solutions are then presented and compared to those of the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The numerical results demonstrate the efficiency of BSAMO and also its best performance in tackling real-world multiphysics problems. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the accelerated overtaking process on the vehicles’ transient aerodynamic characteristics, through 3-D numerical simulations with dynamic meshes and sliding interface technique. Numerical accuracy is verified by experimental results. The aerodynamic characteristics of vehicles in the uniform overtaking process and the accelerated overtaking process are compared. It is shown that the speed variation of the overtaking van would influence the aerodynamic characteristics of the two vans, with greater influence on the overtaken van than on the overtaking van. The simulations of three different accelerated overtaking processes show that the greater the acceleration of the overtaking van, the larger the aerodynamic coefficients of the overtaken van. When the acceleration of the overtaking van increases by 1 m/s2, the maximum drag force, side force and yawing moment coefficients of the overtaken van all increase by more than 6%, to seriously affect the power performance and the stability of the vehicles. The analysis of the pressure fields under different accelerated conditions reveals the cause of variations of the aerodynamic characteristics of vehicles. [ABSTRACT FROM AUTHOR]

Bluff bodies may assume arbitrary attitudes in a flow, causing aerodynamic loads that are sensitive to attitude. The Continuous rotation technique obtains 6-component loads on bluff bodies with 1-degree azimuth resolution about selected axes at a rate of 1 revolution per minute. The load coefficient variation is Fourier transformed and the resulting complex series is truncated in order to obtain rapidly computable, analytical formulae. The method is applied to bluff body shapes including cylinders, a cuboid, a flat plate and a porous box. A cylinder whose length is equal to its diameter, is used to show that rate effects, hysteresis, vortex shedding and other unsteady aerodynamic phenomena are negligible below 10 revolutions per minute. Approaches to generalize the aerodynamic loads on yawed finite cylinders of various aspect ratio are studied. The reasons for differences in aerodynamic load behavior between 2 cylinder models, are analyzed. To complement experiments, the ROTCFD unsteady Navier Stokes code is used to perform diagnostic computations. Methods to generalize the predictions are explored. Maps of the leading coefficients of the Fourier series of each load component over the aspect ratios space, are interpolated. The interpolation varies sharply for aspect ratios between 0.5 to 1. The variation is more gradual beyond aspect ratio 2. By aspect ratio 4, a 'high aspect ratio' limit appears to be reached. [ABSTRACT FROM AUTHOR]

In light of the fact that computational results based on commonly used turbulence models are unsatisfactory, a modified LRN $${k-\varepsilon}$$ turbulence model is proposed. The modified concept includes the introduction of the total stress limitation idea and separation-aware model. With the help of this concept, the transport effects of total turbulent shear stress are taken into consideration and the boundary separation is detected. Thus, the model's ability to simulate laminar-turbulent transition, which is an essential feature of the flow field around vehicles, is improved. The Ahmed model and its corresponding experimental data are introduced to validate and evaluate the modified LRN $${k-\varepsilon}$$ model. Several commonly used turbulence models are also introduced as comparisons. Computations are carried out by the ISIS-CFD flow solver. This work shows that predictions achieved by the modified LRN $${k-\varepsilon}$$ model give a better agreement with experimental data than other solutions. [ABSTRACT FROM AUTHOR]

Supercritical fluid technology offers several advantages in preparation of microparticles. These include uniformity in particle size, morphology, and drug distribution without degradation of the product. One of the recent advantages is preparation of porous aerogel carrier with proper aerodynamic properties. In this study, we aimed to prepare chitosan aerogel microparticles using supercritical fluid (SCF) technology and compare that with microparticles produced by freeze drying (FD). Loading the prepared carriers with a model drug (salbutamol) was also performed. Comparisons of the particle properties and physicochemical characterizations were undertaken by evaluating particle size, density, specific surface area, and porosity. In vitro drug release studies were also investigated. The effect of many variables, such as molecular weight of chitosan oligomers, concentrations of chitosan, and concentrations of tripolyphosphate on the release, were also investigated. Chitosan aerogels were efficiently produced by SCF technology with an average particle size of 10 μm with a tapped density values around 0.12 g/mL, specific surface area (73-103) m/g, and porosity (0.20-0.29) cc/g. Whereas, microparticles produced by FD method were characterized as cryogels with larger particle size (64 microns) with clear cracking at the surface. Sustained release profile was achieved for all prepared microparticles of salbutamol produced by the aforementioned methods as compared with pure drug. The results also demonstrates that chitosan molecular weight, polymer concentration, and tripolyphosphate concentration affected the release profile of salbutamol from the prepared microparticles. In conclusion, SCF technology was able to produce chitosan aerogel microparticles loaded with salbutamol that could be suitable for pulmonary drug delivery system. [ABSTRACT FROM AUTHOR]

The pitch of the spiral finned tube influences seriously to the acoustic resonance in the heat exchanger. In this research, the flow characteristics in relating to the aeolian tone from the finned cylinder are studied by the numerical simulation. It is observed that the tonal noise generated from the finned tube at two pitch spaces. The ratio of the fin pitch to the cylinder diameter is changed at 0.11 and 0.27. The tone level increases and the frequency decreases with the pitch shorter. The separation flow from the cylinder generates the span-wise vortices, Karman vortices, and the separation flow from the fin generates the stream-wise vortices. When the fin pitch ratio is small, the stream-wise vortices line up to span-wise and become weak rapidly. Only the Karman vortices are remained and integrate in span. So the Karman vortex became large. This causes the low frequency and the large aeolian tone. [ABSTRACT FROM AUTHOR]

With the speed upgrade of the high-speed train, the aerodynamic drag becomes one of the key factors to restrain the train speed and energy saving. In order to reduce the aerodynamic drag of train head, a new parametric approach called local shape function (LSF) was adopted based on the free form surface deformation (FFD) method and a new efficient optimization method based on the response surface method (RSM) of GA-GRNN. The optimization results show that the parametric method can control the large deformation with a few design parameters, and can ensure the deformation zones smoothness and smooth transition of different deformation regions. With the same sample points for training, GA-GRNN performs better than GRNN to get the global optimal solution. As an example, the aerodynamic drag for a simplified shape with head + one carriage + tail train is reduced by 8.7%. The proposed optimization method is efficient for the engineering design of high-speed train. [ABSTRACT FROM AUTHOR]

A high-altitude long-endurance aircraft with high-aspect-ratio wing usually generates large deformation, which brings the geometric nonlinear aeroelastic problems. In recent decades, it has become a key focus of the international researchers of aeroelasticity. But some critical technologies are not developed systematically, such as aerodynamic calculation methods of the curved wing with deformation, moreover, there are few experimental validations of these technologies. In this paper, we established the steady aerodynamic calculating method of the curved wing with quite large deformation based on the extended lifting line method, and calculated the unsteady aerodynamics using the strip theory considering curved surface effects. Combining the structure geometrical nonlinear finite element method, we constructed a systematic analytic approach for the static aeroelasticity and flutter of very flexible wing, and further designed the ground vibration and wind tunnel test to verify this approach. Through the test and the theoretic results comparison, we concluded that the extended lifting line method has adaptable precision for the static aeroealsticity and the strip theory considering curved surface effects for flutter analysis can give exact critical speed and flutter mode when the dynamic stall does not happen. The work in this paper shows that the geometric nonlinear aeroelastic analytic approach for very flexible wing has very high efficiency and adaptable precision. It can be used in the engineering applications, especially the iterated design in preliminary stage. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) magnetic levitation (maglev) vehicle is a fascinating transportation tool due to its unique inherent stability. In order to improve performance of present HTS maglev vehicle system, a novel HTS maglev vehicle (aero-vehicle) utilizing aerodynamic designs from modern aircraft is proposed, which is driven by an engine positioned on the top of the car body. The aerodynamic designs of the aero-vehicle include the wings and the empennage, and these new designs are used to adjust and control the pitch, roll, and yaw of the car body. To analyze the feasibility of the aero-vehicle, its characteristics are investigated in the paper. Depending on ailerons of wings, elevator and rudder of the empennage, the aero-vehicle is capable to advance safety and ride comfort of present HTS maglev vehicle. [ABSTRACT FROM AUTHOR]

The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China. An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT, validated with published data, was used to solve the gas-solid multiphase flow of a sandstorm around a train. The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated. Results showed that in sandstorm weather, the drag, lift, side forces and overturning moment increase by variable degrees. Based on a numerical analysis of aerodynamic characteristics, an equation of train stability was also derived using the theory of moment balance from the view of dynamics. A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis. [ABSTRACT FROM AUTHOR]

In time trial cycling stage, aerodynamic properties of cyclists are one of the main factors that determine performances. Such aerodynamic properties are strongly dependent on the cyclist ability to get into the most suitable posture to have minimal projected frontal area facing the air. The accurate knowledge of the projected frontal area ( A) is thus of interest to understand the performance better. This study aims for the first time at a model estimating accurately A as a function of anthropometric properties, postural variations of the cyclist and the helmet characteristics. From experiments carried out in a wind tunnel test-section, drag force measurements, 3D motion analysis and frontal view of the cyclists are performed. Computerized planimetry measurements of A are then matched with factors related to the cyclist posture and the helmet inclination and length. Data show that A can be fully represented by a rate of the cyclist body height, his body mass, inclination and length of his helmet. All the above-mentioned factors are thus taken into account in the present modelling and the prediction accuracy is then determined by comparisons between planimetry measurements and A values estimated using the model. [ABSTRACT FROM AUTHOR]

Proniosomes are free-flowing systems with coating carriers, which developed as a method for improving the drug flow and pulmonary delivery. Extensive research on proniosomes was done to enhance the dry powder inhalers (DPI)'s inhalation performance. This research aimed at studying the impact of lactose-mannitol mixture additives on the proniosome's physicochemical properties as a method for improving the inhalation efficiency of DPI. Vismodegib has been employed as a compound model. Box–Behnken design has been employed to prepare different proniosomes formulae by incorporating various (A) span 60 concentrations, (B) lactose concentrations and (C) mannitol: total carrier mixture. The measured responses were vesicle size (R1), %release (R2), Carr's index (R3) and %recovery (R4). The results displayed that R1 and R4 were significantly antagonistic to C and significantly synergistic to both A and B while R2 and R3 were significantly synergistic to C and significantly antagonistic to both A and B. The optimal formula was selected for its aerodynamic behaviour, cytotoxic activity and bioavailability assessment. The optimal formula resulted in better Vismodegib lung deposition, cytotoxic activity and relative bioavailability. This novel formula could be a promising carrier for sustained delivery of drugs via the pulmonary route. [ABSTRACT FROM AUTHOR]

The numerical simulation based on Reynolds time-averaged equation is one of the approved methods to evaluate the aerodynamic performance of trains in crosswind. However, there are several turbulence models, trains may present different aerodynamic performances in crosswind using different turbulence models. In order to select the most suitable turbulence model, the inter-city express 2 (ICE2) model is chosen as a research object, 6 different turbulence models are used to simulate the flow characteristics, surface pressure and aerodynamic forces of the train in crosswind, respectively. 6 turbulence models are the standard k-ε, Renormalization Group (RNG) k-ε, Realizable k-ε, Shear Stress Transport (SST) k-ω, standard k-ω and Spalart–Allmaras (SPA), respectively. The numerical results and the wind tunnel experimental data are compared. The results show that the most accurate model for predicting the surface pressure of the train is SST k-ω, followed by Realizable k-ε. Compared with the experimental result, the error of the side force coefficient obtained by SST k-ω and Realizable k-ε turbulence model is less than 1 %. The most accurate prediction for the lift force coefficient is achieved by SST k-ω, followed by RNG k-ε. By comparing 6 different turbulence models, the SST k-ω model is most suitable for the numerical simulation of the aerodynamic behavior of trains in crosswind. [ABSTRACT FROM AUTHOR]