Complicated Configurations Research Articles

The Study of Optimal Performance Improvement Method for Aircraft of Various Variants within the Same Type

In this paper, we studied the optimal method of improving performance for aircraft having various variants within the same type. The study defined configuration of an entire fleet of aircraft being subject to a performance improvement program. And selected the most complicated aircraft configuration among them as a Standard Aircraft for modification by according to the proposed Aircraft Selection Process for developing an optimal Aircraft Performance Improvement Process. Based on the selected the Standard Aircraft, drew a system integration design result and carried out Evaluation Test and obtained Airworthiness Certification. Created the database with the design data of the Standard Aircraft, Evaluation Test, and Airworthiness Certification results, and applied it to variants of aircraft to complete the performance improvement program with optimized schedules and costs. By applying the proposed method to IFF performance improvement program, drew optimal system integration design and completed the program with minimized schedule.

Kinetics‐Controlled Interfacial Synthesis of Janus and Patchy Heterostructures Based on Perovskite Nanocrystals

AbstractHeterostructures integrated by diverse material featuring nanocrystals (NCs) tunable properties and functions are of great interest. However, to rationally design and precisely control the heterostructures in multiple shapes still remains a tremendous challenge. In this work, the nucleation of SiO2 nanoparticles is manipulated via a kinetics‐controlled water–hexane interfacial reaction system to construct Cs3Cu2I5/SiO2 heterostructures, which can be well controlled in Janus and patchy morphology. In this interfacial reaction, the evolution of Cs3Cu2I5 NCs and the intrinsic formation mechanism of the heterostructures are investigated. It is observed that the Cs3Cu2I5 NCs on the interface undergo a morphology transformation driven by ligand loss and exposed facets evolution. Increased wettability between Cs3Cu2I5 and SiO2 favors the formation of Cs3Cu2I5/SiO2 heterostructures. The key to this strategy is to break the rule of thermodynamic domination in reaction by kinetics manipulation when constructing the patchy heterostructure. To be noted, an increased stability is conferred on the resultant heterostructure product compared to naked perovskite NCs. This work enables to better control the complicated heterostructure configurations and understand their formation mechanism.

A review on magnetically assisted abrasive flow machining and abrasive material type

The development of fine surface finish with no defects is still a significant challenge for the present industry and the finishing operation in the manufacturing of the precision components is the major problem. It is difficult rather impossible to polish/finish the difficult-to-reach surfaces, internal surfaces, and complex geometries by existing finishing methods. Abrasive flow machining (AFM) is a well-established advanced finishing process that can meet the required finishing requirements. However, the main disadvantages of this process are the surface integrity with low surface finish and high machining times. Magnetically Assisted Abrasive flow machining (MAAFM) is one of the non-conventional machining techniques that can successfully handle these problems. This process was developed in the early 2000s as a technique for deburring, polishing, and radiusing tough to reach surfaces like complicated configurations and edges/boundaries by flowing a magnetic abrasive polymeric medium across them. Magnetic flux density (MFD), extrusion pressure, flow volume, abrasive type, grit size, number of process cycles, medium, and workpiece configuration are the principal machining parameters that control the surface finish characteristics. The medium extruded forward and backward between two vertically opposed hydraulic cylinders across transit created by the workpiece and tooling. Abrasion of workpiece takes place wherever the medium proceeds across the highly confining transit. The major elements of the MAAFM process are the machine, tooling, and the magnetic abrasives containing media. MAAFM has a wide scope of uses in industries including automotive, aviation, precision dies, medicinal, electronics. This article represents a review of current advancements in the area of the MAAFM process and the type of magnetic abrasive particles (MAPs) used.

Code development of Single-phase 2-D pressure wave propagation

Obtaining accurate capture of the pressure wave propagation process is very important for structural load calculation and stress analysis. For traditional nuclear reactors, one-dimensional system analysis codes such as RELAP5 and TRACE are recognized to be the effective analysis tools for pressure wave propagation simulating. However, advanced nuclear energy systems have a highly integrated and complicated geometric configurations. It is obvious that the system analysis codes are difficult to obtain an elaborate simulating of pressure wave propagation process. It is significant to develop multi-dimensional pressure wave propagation simulation codes. In this paper, a 2-D single-phase pressure wave propagation calculating code is developed. Furthermore, code verifications are carried out by using two typical single-phase shock tube benchmarks. Finally, two-dimensional propagation characteristics of pressure wave are investigated. Conclusions can be drawn that the new code proposed in this paper can reasonably reproduce the behaviors of multi-dimensional pressure wave propagation.

Numerical simulations of folding mechanics in nonlinear plates using discontinuous rotations

A wide range of modern and advanced structural applications includes self-folding materials and origami metamaterials. Simulation tools capable of modelling creases in continuum media have become desirable to keep up with such technological advancements.We present an approach to simulate folding as sharp discontinuities in the Euler rotations of nonlinear plates. We used large deformations and large rotations within a first-order shear plate theory. The novel finding is a set of constraints that the rotation jumps must satisfy on a crease. We used a meshfree method to implement such conditions and check their effectiveness. We verified the numerical solutions against available analytical and semi-analytical solutions. We show that the proposed idea works well also for more complicated configurations, such as rigid origami motions with multiple folding lines and crumpled sheets with random creases.

A Handheld Microwave Thermoacoustic Imaging System With an Impedance Matching Microwave-Sono Probe for Breast Tumor Screening.

Microwave-induced thermoacoustic imaging (MTAI) is a promising alternative for breast tumor detection due to its deep imaging depth, high resolution, and minimal biological hazards. However, due to the bulky size and complicated system configuration of conventional benchtop MTAI, it is limited to imaging various anatomical sites and its application in different clinical scenarios. In this study, a handheld MTAI system equipped with a compact impedance matching microwave-sono and an ergonomically designed probe was presented and evaluated. The probe integrates a flexible coaxial cable for microwave delivery, a miniaturized microwave antenna, a linear transducer array, and wedge-shaped polystyrene blocks for efficient acoustic coupling, achieving microwave illumination and ultrasonic detection coaxially, and enabling high signal-to-noise ratio (SNR). Phantom experiments demonstrated that the maximum imaging depth is 5 cm (SNR = 8 dB), and the lateral and axial resolutions are 1.5 mm and 0.9 mm, respectively. Finally, three healthy female volunteers of different ages were subjected to breast thermoacoustic tomography and ultrasound imaging. The results showed that the h-MTAI data are correlated with the data of ultrasound imaging, indicating the safety and effectiveness of the system. Thus, the proposed h-MTAI system might contribute to breast tumor screening.

Artificial Intelligence Powered Mobile Networks: From Cognition to Decision

Mobile networks (MNs) are anticipated to provide unprecedented opportunities to enable a new world of connected experiences and radically shift the way people interact with everything. MNs are becoming more and more complex, driven by ever increasing complicated configuration issues and blossoming new service requirements. This complexity poses significant challenges in deployment, management, operation, optimization, and maintenance, since they require complete understanding and cognition of MNs. Artificial intelligence (AI), which deals with the simulation of intelligent behavior in computers, has demonstrated enormous success in many application domains, suggesting its potential in cognizing the state of an MN and making intelligent decisions. In this article, we first propose an AI-powered MN architecture and discuss challenges in terms of cognition complexity, decisions with high-dimensional action space, and self-adaptation to system dynamics. Then potential solutions associated with AI are discussed. Finally, we propose a deep learning approach that directly maps the state of an MN to perceived QoS, integrating cognition with the decision. Our proposed approach helps operators to make more intelligent decisions to guarantee QoS. Meanwhile, the effectiveness and advantages of our proposed approach are demonstrated on a real-world dataset involving 31,261 users over 77 stations within 5 days.

Spatial control over ultrasonic cleaning of mining equipment using a phased array technology

Purpose. To develop methods for spatial control over ultrasonic cleaning by using ultrasonic phased array of radiators. To simulate the cleaning process using the developed methods to prove their effectiveness. Methodology. Application of the ultrasonic array as a basic radiator for ultrasonic cleaning enables redistribution of intensity in the bath by increasing it in the most contaminated zones of the cleaned object. Geometric and physical laws provide analytically defined parameters of the beam. Findings. The authors determine basic parameters for the ultrasonic beam through considering input and output data of the 3-D fuzzy interval controller. The focus distance is calculated by means of the arrival time of the threshold signal considering distances between the sensor and the array. The azimuth is directed into the bath center and dependent on its height only. The zenithal angle is calculated as a ratio of intensities of the current arrays and the nearest adjacent ones towards the greatest one. By default, the beam is directed to the bath center for the phased array with the greatest intensity. The simulation reveals that the applied approach enables a 41.5% increase in intensity in the contamination zone, this improving energy efficiency of cleaning and reducing time required for ultrasonic treatment. Originality. The authors suggest new methods for forming control over ultrasonic cleaning, which enables considering spatial distribution of this process by optimizing energy losses. Practical value. The new approach to spatial control over ultrasonic cleaning enables redirecting intensity in the bath to the most contaminated zones, this allowing an increase in energy efficiency of large mining machines of complicated configuration.

Miniature Fourier transform spectrometer based on a fiber-tip interferometer.

The miniaturization of spectrometers have attracted much attention owning to the demand for portable or in situ spectral analysis in a wide variety of fields, but it is a great challenge to push them into practical applications due to high cost, complicated configuration, and sensitivity to external disturbance. We report on a miniature Fourier transform (FT) spectrometer based on fiber-tip Fizeau interferometer. Hand pulling or any other types of force can be used to drive optical path difference (OPD) scan. Interferences are monitored as a function of time by two photodetectors, one is used to detect the whole interferogram while the other to measure single-wavelength interferogram. In this design, the instantaneous interference intensity as well as OPD can be obtained in an accurate way so that the exact spatial interferogram of the incident spectrum can be worked out. Consequently, the incident spectrum can be retrieved by FT method. A resolution of 7.69 cm-1 in the wavelength range of 1400 nm ∼ 1700 nm is achieved. Experimental results show that the performance of our device is comparable to the commercial benchtop spectrometer. Our device is independent of the complicated fabrication procedures, easy of usage, and cost effective. We envision that the proposed design will inspire a new concept for constructing simple and cheap spectrometers that is well suited for practical applications.

Vertucci\u2019s root canal configuration of 11,376 mandibular anteriors and its relationship with distolingual roots in mandibular first molars in a Cantonese population: a cone-beam computed tomography study

BackgroundCone-beam computed tomography (CBCT) was used to study the root canal system of mandibular anteriors (MAs) in a Cantonese population and to evaluate the correlation between the complicated root canal configurations of mandibular lateral incisors (MLIs) and the presence of distolingual roots (DLRs) in mandibular first molars (MFMs).MethodsA total of 11,376 mandibular anterior teeth were scanned by CBCT. Those whose images met the inclusion criteria were first analysed according to Vertucci's root canal configuration and then grouped based on gender, age, and side, and their effects on root canal morphology were analysed. Finally, statistical analysis was used to evaluate the correlation between the complicated root canal configurations of MLIs and the existence of DLRs in MFMs. All statistical analyses were performed by using SPSS 25.0 software. Quantitative data are presented as the mean ± standard deviation. Student’s t tests were used to calculate statistical significance. P < 0.05 was considered statistically significant.ResultsIn MAs in the Cantonese population, all mandibular central incisors (MCIs) and MLIs had one root, and 0.37% of mandibular canines (MCs) had two roots. The most common Vertucci's root canal configuration was Vertucci I followed by Vertucci III. A total of 30.91% of MLIs and approximately 8% of MCIs and MCs have complicated root canal configurations. There were no significant differences in the prevalence of DLRs in MFMs and the incidence of complicated root canal configurations of MLIs between males and females or between the right and left teeth. However, a significant difference was found in different age groups of root canal configurations in MLIs. Moreover, significant ipsilateral and contralateral correlations between MFMs with DLRs and MLIs with complicated root canal configurations were observed on both sides.ConclusionIn Cantonese population, the possibility of complicated root canal configuration in MLIs was higher, when DLR appeared in MFMs.

Overview of Prospects for Service-Aware Radio Access towards 6G Networks

The integration of space–air–ground–sea networking in 6G, which is expected to not only achieve seamless coverage but also offer service-aware access and transmission, has introduced many new challenges for current mobile communications systems. Service awareness requires the 6G network to be aware of the demands of a diverse range of services as well as the occupation, utilization, and variation of network resources, which will enable the capability of deriving more intelligent and effective solutions for complicated heterogeneous resource configuration. Following this trend, this article investigates potential techniques that may improve service-aware radio access using the heterogeneous 6G network. We start with a discussion on the evolution of cloud-based RAN architectures from 5G to 6G, and then we present an intelligent radio access network (RAN) architecture for the integrated 6G network, which targets balancing the computation loads and fronthaul burden and achieving service-awareness for heterogeneous and distributed requests from users. In order for the service-aware access and transmissions to be equipped for future heterogeneous 6G networks, we analyze the challenges and potential solutions for the heterogeneous resource configuration, including a tightly coupled cross-layer design, resource service-aware sensing and allocation, transmission over multiple radio access technologies (RAT), and user socialization for cloud extension. Finally, we briefly explore some promising and crucial research topics on service-aware radio access for 6G networks.

Two-phase heat transfer correlations in three-dimensional hierarchical tube

Development of novel enhanced surface tubes is an important way to advance two-phase flow heat transfer. To make correlations of two-phase flow heat transfer in enhanced tubes with acceptable prediction has been a challenge for many years. The paper presents a method: two-phase heat transfer correlations in enhanced tubes are directly developed through existing two-phase heat transfer smooth-tube models by introducing several modifying factors and dimensionless numbers. An enhanced heat transfer tube containing staggered arrays of three-dimensional dimples and secondary petal-shaped protrusions (EHT) is one of the most complicated internal surface-tube configurations on the market. Visualizations of flow patterns and measurements of heat transfer coefficients of two-phase flow using refrigerant R410A in smooth and EHT tube are conducted. Detailed visualization experiments during two-phase flows show good agreements between flow regimes and flow-pattern maps in smooth and EHT tube. The equation of continuity is adopted to provide understanding of the mechanism of the agreements. Both theoretical analysis and experimental studies support the method. As a result of using it, new two-phase heat transfer correlations are developed in enhanced tubes as the EHT tube is an example. Flow boiling correlation can predict data points within +10% to -20% and flow condensation correlation can predict data points within ±10% in the EHT tube.

Stress influence matrix on hot spot stress analysis for welded tubular joint in offshore jacket structure

The detailed finite element (DFE) simulation of welded offshore tubular joint can give realistic and sound hot-spot stress (HSS) estimates regarding fatigue design of jacket substructures for offshore wind turbines. However, the computational efforts and time costs due to complicated joint configurations and a large quantity of design load cases have prompted the design practitioners likely resort to a simple alternative, the SCF method, which is also rooted in the DFE simulation. The present study attempted to optimize the conventional DFE simulation procedure by applying a stress influence matrix (SIM) method and its modified version gSIM, along with discrete joint formulation techniques, to simplify and make efficient of the DFE process, and then incorporating point positioning techniques to eventually ease the HSS evaluation. Through an implementation case involving a KK tubular joint, the gSIM method proved its robustness, reliability and computationally efficiency in joint HSS evaluation practice.

Systematic modeling of electrostatic radiation shields for deep space flight

Astronauts are exposed to a unique radiation environment during space missions. This environment is dominated by high charge and energy (HZE) ions with sources that include solar energetic particles (SEPs), galactic cosmic rays (GCRs), and trapped electrons and protons around planetary bodies with substantial magnetic fields. Traditional shielding strategies aim to reduce astronaut radiation exposure by increasing vehicle mass, but this is ineffective for the extremely penetrating GCRs. Use of electromagnetic fields has been investigated previously, but these studies have been limited to single point designs. The NASA Active Shielding project has instead developed a workflow that includes a fast and accurate particle propagation code (Active Shielding Particle Pusher), which can be used to rapidly evaluate the shielding efficacy of many different permutations of electromagnetic shielding designs. While some validation of the code has been previously done, additional validation is needed to increase user confidence in simulation results involving more complicated electrostatic conductor configurations. In the present study, we evaluated shielding properties of spherical electrode arrays and planar grid structures against 2 MeV or 6 MeV H+ and 22.5 MeV Fe6+ ions using ASPP, SIMION, and COMSOL, and compared these results to laboratory-based measurements. Many numerical experiments were conducted to reproduce experimental ion beam tests that measure the consequential particle reduction rate in a safe zone compared to the initial number of ions. The experimental visualizations were also compared with the present numerical results and found to be in close agreement with each other for all considered voltage combinations applied to electrode structures. This comparison allows us to use numerical models to predict the behavior of complex shielding structures at much larger scales not feasible in a laboratory environment.

Rope tension analysis based on single spring model against elevator rope

Elevators run vertically by suspension ropes, therefore each rope has to be adjusted correctly to fulfill each tension balance. That contributes to establish a long life against elevator ropes. If a groove wear of the traction sheave causes difference against other grooves, the difference induces rope tension fluctuation while changing the car position. Conventional elevator models to evaluate the rope tension have not considered the detailed winding behavior of the rope on the sheave. As the winding amount of the rope contains the rope deformation, the deformation should be considered to evaluate the rope length and the rope tension in an elevator tension model. This paper shows a simple elevator model with a single spring model against the rope. The derived model can not only calculate the appropriate winding amount against the rope spring model, but also get a faster solution even though the elevator system has a complicated roping configuration. The proposed simulation model is validated by experiments.

PIV-system for flow measurements on the benchmark of promising fast neutron nuclear reactor

Carrying out spatio-temporal flow fields parameters is one of the most important and complicated problem within the modeling of heat and hydrophysical processes in operating regimes of the power plants (including nuclear (NPP)). Particle Image Velocimetry (PIV) method (based on the flow visualization, using laser illumination) fits best to satisfy the demands of such measurements. For the experiments on large-scale models of NPP, there is a number of problems in the application of this method, for example, large scales of the flows of the investigated model objects; a noticeable variability of the flow parameters processes with strong temperature fluctuations, leading to optical distortions; necessity of combining imaging and contact gauges probing etc. In this paper we describe PIV- system specifically designed for the study of heat and hydrophysical processes in large-scale model setup of promising fast neutron reactor. The system allows the PIV-measurements for the conditions of complicated configuration of the reactor model, reflections and distortions section of the laser sheet, blackout, in a closed volume. The illumination system using of two lasers and two video cameras with synchronization, allows to obtain an image of the flow in the whole volume of investigation. The use of filtering techniques and method of masks images enabled us to reduce the number of incorrect measurement of flow velocity vectors by an order. The method of conversion of image coordinates and velocity field in the reference model of the reactor using a virtual 3D simulation targets, without loss of accuracy in comparison with a method of using physical objects in filming area was released. The results of measurements of velocity fields in various modes, both stationary (operational), as well as in non-stationary (emergency). These results are compared with measurements of temperature distribution, which were carried out simultaneously. The obtained data set can be used for verifying CFD codes.

A critical review on Classification of materials used in 3D printing process

In recent years, 3D printing technology has demonstrated its usefulness in a variety of fields because it provides faster, easier, and less expensive solutions, as well as the ability to build a variety of complicated configurations that must overlap many traditional production processes. It has gained attention from all around the globe as a developing method for producing complex three-dimensional products applicable in several industries, like aerospace, automotive, healthcare, biomedical, construction, food, and textile. The key advantages of 3D printing are design freedom, design customization, waste reduction, the capacity to build complicated structures, and quick prototyping. Using 3D CAD models and 3D printers, different types of materials can be printed layer over layer. Metals and alloys, ceramics, polymers, composites, smart materials, concrete, and biomaterials are often utilized in 3D printing technologies. In this article, we go through a wide selection of materials applied in 3D printing. Applications of 3D printed products made of different materials and different processes of 3D techniques are also described in the article and concluded with suggestions for future research in this field. New researchers and industrial people on 3D printing would benefit from the outcomes of this article.

Experimental and numerical investigation of brazed plate heat exchangers – A new approach

• Thermofluid characteristics of brazed plate heat exchanger (BPHE) are studied. • Effect of brazing joints in numerical modeling of BPHEs is investigated. • The brazing joint imposes significant effect on pressure drop. • The brazing joint casts very minor influence on heat transfer. • The numerical predictions are in good agreements with existing correlations. Experimental and numerical investigations of a brazed plate heat exchanger are performed in this study. Three approaches are considered in numerical modeling of brazed plate heat exchanger in order to realize the difference amid simulations and experimental data. The departures between simulations and experiments are strongly associated with the complicated configurations of the plate geometry. Hence, modeling regarding the modified geometry, modeling of original geometry, and modeling of original geometry by considering brazing joints are conducted in numerical simulations for elaborations. Results show that the third geometry yields the best agreement with the experimental data, indicating the importance of considering brazing joints in the modeling of brazed plate heat exchangers. However, the modified geometry has the worst agreement with the experimental data. This approach has been adopted by many existing literatures. Flow field for all approaches illustrates that a zig-zag pattern from the inlet to outlet nozzles exists. This is because of large chevron angle of plates (75°). Comparison of Nusselt number and friction factor of this brazed plate heat exchanger with the existing correlations demonstrates the necessity of developing new correlations for brazed plate heat exchangers. Correlations for Nusselt number and friction factor of the modeled heat exchangers are developed in a wide range of Reynolds number (50–10,000) with mean deviations of 5.1% and 3.4%, respectively.

Linking Time-Domain Vibration Behaviors to Spatial-Domain Propagating Waves in a Leaf-like Gradient-Index Phononic Crystal Lens

It is known that a propagating wave at a certain spatial point can be decomposed into plane waves propagating at different angles. In this work, by designing a gradient index phononic crystal lens (GRIN PCL) with transverse-continuous leaf-like unit cells, we theoretically and experimentally show that the spatial-domain propagating waves in finite periodic structures can be linked to their time-domain vibration behaviors. The full-field instantaneous focusing behaviors of Lamb waves in the proposed leaf-like GRIN PCL give an example of the wave-vibration linkage in finite periodic structures while allowing a certain complexity. The conclusion in this paper can help one skip iterative time-consuming finite element analysis (e.g., time-stepping solutions) to avoid possible numerical instabilities occurred in calculating transient wave field on practical finite metamaterials or phononic crystals having unit cells with complicated configurations.

Unsteady aerodynamic simulations by the lattice Boltzmann method with near-wall modeling on hierarchical Cartesian grids

Near-wall modeling for large-eddy simulation (LES) based on the lattice Boltzmann method (LBM) is applied to the unsteady aerodynamic simulations around the tandem cylinders and the 30P30N three-element high-lift airfoil using hierarchical Cartesian grids. The near-wall modeling of the inner turbulent boundary layer is essential for LES to accurately calculate the high Reynolds number wall-bounded turbulent flow with a reasonable calculation cost. Therefore, near-wall modeling for LES has been studied within the framework of the Navier–Stokes equations. However, LBM-based modeling is still in its early developing stage because of the LBM’s calculation algorithm using distribution functions on a non-body fitted Cartesian grid, and further developments are needed regarding the applicability to flow simulations around arbitrary complicated shapes that appear in the actual engineering field. In this study, aerodynamic simulations around tandem cylinders are conducted using the proposed near-wall modeling that reproduces the profiles of the turbulent boundary layer in turbulent channel flow simulations on a non-body-fitted Cartesian grid. The same benchmark problem is also calculated using the non-slip wall boundary condition (interpolated bounce-back scheme) for comparison. Those calculation results are validated through the comparisons with the available experimental measurements, and the effectiveness of the proposed near-wall modeling to high Reynolds number wall-bounded turbulent flow simulations around objects with curvilinear surfaces is demonstrated. Followed by the tandem cylinders, the aerodynamic simulation around the 30P30N three-element high-lift airfoil is also conducted in order to demonstrate the applicability to more complicated shapes. The simulation result shows that the proposed method can stably calculate the relatively complicated configuration such as the high-lift airfoil, and the potential of the proposed method to unsteady aerodynamic simulations around arbitrary complicated shapes is demonstrated.