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This paper aims to provide a shimming method based on scanned data and finite element analysis (FEA) for a wing box assembly involving non-uniform gaps. The effort of the present work is to deal with gap compensation problem using hybrid shims composed of solid and liquid forms.

First, the assembly gaps of the mating components are calculated based on the scanned surfaces. The local gap region is extracted by the seed point and region growth algorithm from the scattered point cloud. Second, with the constraints of hole margin, gap space and shim specification, the optional shimming schemes are designed by the exhaustive searching method. Finally, the three-dimensional model of the real component is reconstructed based on the reverse engineering techniques, such as section lines and sweeping. Using FEA software ABAQUS, the stress distribution and damage status of the joints under tensile load are obtained for optimal scheme selection.

With the scanned mating surfaces, the non-uniform gaps are digitally evaluated with accurate measurement and good visualization. By filling the hybrid shims in the assembly gaps, the joint structures possess similar load capacity but stronger initial stiffness compared to the custom-shimmed structures.

This method has been tested with the interface data of a wing tip, and the results have shown good efficiency and automation of the shimming process.

The proposed method can decrease the manufacturing cost of shims, shorten the shimming process cycle and improve the assembly efficiency.

The purpose of this paper is to evaluate the cogging torque in a surface-mounted permanent magnet (SPM) machine with both uniformly and non-uniformly segmented stator cores and to find out the optimal solution of stator core segmenting.

The cogging torque with segmented stators is synthesized from a single slot model, and analytical prediction is given to analyze the cogging torque with both uniformly and non-uniformly segmented stators. Finite element method (FEM) is used to figure out the electromagnetic field and validate the analytical prediction. Moreover, models with various shapes and positions of connecting tongues between the stator core segments are explored to achieve the optimal design.

The cogging torque is found to be greatly related to the number of segments and the electrical angle between adjacent additional air gaps caused by the tolerance of stator segments. Different shapes of the connecting tongues are tested and proved to be of great importance to the flux density, both radial and tangential, and therefore affect the cogging torque. Finally, position of the connecting tongues is perceived to have little influence on the performance of machine.

By utilizing analytical prediction and FEM calculation, the optimal solution is discussed to minimize the cogging torque in the SPM machine from the perspective of the stator core segmentation.

This paper establishes formula of cogging torque with segmented stators and predicts the variation of cogging torque with analytical method. Besides, different combinations of segments are compared and measures to reduce the cogging torque produced by the segmentation are proposed.

(1) A mathematical model for the Hybrid nanofluids flow is used as carriers for delivering drugs. (2) The flow conditions are controlled to enable drug-loaded nanofluids to flow through the smaller gap between the two tubes. (3) Hybrid nanofluids (HNFs) made from silver (Ag) and titanium dioxide (TiO₂) nanoparticles are analyzed for applications of drug delivery. (Ag) and (TiO₂) (NPs) are suitable candidates for cancer treatment due to their excellent biocompatibility, high photoactivity, and low toxicity. (4) The new strategy of artificial neural networks (ANN) is used which is machine-based and more prominent in validation, and comparison with other techniques.

The two Tubes are settled in such a manner that the gap between them is uniform. The Control Volume Finite Element Method; Rk-4 and Artificial Neural Network (ANN).

(1) From the obtained results it is observed that the dispersion and distribution of drug-loaded nanoparticles within the body will be improved by the convective motion caused by hybrid nanofluids. The effectiveness and uniformity of drug delivery to target tissues or organs is improved based on the uniform flow and uniform gap. (2) The targeting efficiency of nanofluids is further improved with the addition of the magnetic field. (3) The size of the cylinders, and flow rate, are considered uniform to optimize the drug delivery.

(1)The flow phenomena is considered laminar, one can use the same idea through a turbulent flow case. (2) The gap is considered uniform and will be interesting if someone extends the idea as non-uniform.

(1) To deliver drugs to the targeted area, a suitable mathematical model is required. (2) The analysis of hybrid nanofluids (HNFs) derived from silver (Ag) and titanium dioxide (TiO₂) nanoparticles is conducted for the purpose of drug delivery. The biocompatibility, high photoactivity, and low toxicity of (Ag) and (TiO₂) (NPs) make them ideal candidates for cancer treatment. (3) Machine-based artificial neural networks (ANN) have a new strategy that is more prominent in validation compared to other techniques.

The drug delivery model is a useful strategy for new researchers. (1) They can extend this idea using a non-uniform gap. (2) The flow is considered uniform, the new researchers can extend the idea using a turbulent case. (3) Other hybrid nanofluids flow, in the same model for other industrial usages are possible.

All the obtained results are new. The experimental thermophysical results are used from the existing literature and references are provided.

This paper aims to further develop stator permanent magnet (PM) type memory machines by providing generalized design guidelines for double-stator memory machines (DSMMs) with hybrid PMs. This paper discusses the design experience of DSMMs and presents a comparative study of radial magnetization (RM) and circumferential magnetization (CM) types.

It begins with an introduction to RM and CM operating principles and magnetization mechanisms. Then, a comparative study is conducted for one of the RM-DSMM rotor pole pairs, inner and outer stator clamping angles and low coercive force PMs thickness. Finally, the two machines’ finite element simulation performance is compared. The validity of the proposed machine structure is demonstrated.

In this paper, the double-stator structure is extended to parallel hybrid PM memory machines, and two novel DSMMs with RM and CM configurations are proposed. Two types of DSMMs have PMs and magnetizing windings on the inner stator and armature windings on the outer stator. The main difference between the two is the arrangement of PMs on the inner stator.

Conventional stator PM memory machines have geometrical space conflicts between the PM and armature windings. The proposed double-stator structure can alleviate these conflicts and increase the torque density accordingly. In addition, this paper contributes to comparing the arrangement of hybrid PMs for DSMMs.

The purpose of this paper is to provide the details of developments to research works in the distribution characteristics of the air gaps within firefighters’ clothing and research methods to evaluate the effect of air gaps on the thermal protective performance of firefighters’ clothing.

In this paper, the distribution of air gaps within firefighters’ clothing was first analyzed, and the air gaps characteristics were summarized as thickness, location, heterogeneity, orientation and dynamics. Then, the evaluation of the air gap on the thermal protective performance of fighters’ clothing was reviewed for both experimental and numerical studies.

The air gaps within clothing layers and between clothing and skin play an important role in determining the thermal protective performance of firefighters’ protective clothing. It is obvious that research works on the effects of actual air gaps entrapped in firefighters’ clothing on thermal protection are comparatively few in number, primarily focusing on static and uniform air gaps at the fabric level. Further studies should be conducted to define the characteristic of air gap, deepen the understand of mechanism of heat transfer and numerically simulate the 3D dynamic heat transfer in clothing to improve the evaluation of thermal protective performance provided by the firefighters’ clothing.

Air gaps within thermal protective clothing play a crucial role in the protective performance of clothing and provide an efficient way to provide fire-fighting occupational safety. To accurately characterize the distribution of air gaps in firefighters’ clothing under high heat exposure, the paper will provide guidelines for clothing engineers to design clothing for fighters and optimize the clothing performance.

This paper is offered as a concise reference for researchers’ further research in the area of the effect of air gaps within firefighters’ clothing under thermal exposure.

The purpose of this paper is to present a detailed advanced dynamical model of induction machine (IM) with unskewed rotor bars, including rotor slot harmonics.

Procedure of IM modeling using results from finite element analysis (FEA). Series of magneto-static FEA simulations are used to obtain matrix of IM inductances as a function of rotor angular position and geometry. Each element in this matrix is represented by Fourier series (FS) and incorporated in proposed dynamical model. Using or neglecting various elements in FS of inductance matrix may be useful for determining which component of the series has dominant influence on harmonic content of stator currents, torque ripple or speed variation. The usefulness of application of presented model is verified comparing with time-stepping FEA simulations.

Although the model is not suitable for usage in on-line regulation of IM drives, but the results of simulations may be used to thoroughly explain origins of higher order harmonics in stator currents of IM and help improve sensorless speed estimation algorithms and fault diagnostics.

This paper shows an approach to the modeling of IM which includes effects of non-uniform air gap and non-sinusoidal distributions of magneto-motive forces. Inductance matrix elements are complex functions of rotor position, geometry and winding distributions and it gives an opportunity for detail analysis of IM behavior in numerous applications.

In order to keep the advantages of PM generators and eliminate its disadvantage – difficulty in regulating the magnetic field, hybrid excitation is an effective way. The purpose of this paper is to propose a novel way to achieve hybrid excitation by use of tooth harmonic field.

Unlike weakening the tooth harmonics field and EMF in traditional machines, in this paper the tooth harmonics field is proposed to form a novel hybrid excitation permanent magnet synchronous generator (HEPMSG).

The generation mechanism of tooth harmonic electromotive force (EMF) of rotor winding is introduced, and its influencing factors are discussed in detail. The matching design of tooth harmonic winding and field winding for maximum output field current of tooth harmonic excitation system is analyzed.

This machine can achieve not only effective adjustment of the air-gap magnetic field, but also elimination of the brushes and slip rings.

Unlike weakening the tooth harmonics field and EMF in traditional machines, in this paper the tooth harmonics filed is proposed to form a novel hybrid excitation PM synchronous generator. This machine can achieve not only effective adjustment of the air-gap magnetic field, but also elimination of the brushes and slip rings.

Studying manufacturing process of compressor blade can reduce the production cost and time in aircraft turbo‐engine industries. In the cold roll‐forging of thin compressor blades, the elastic behavior of machine structure and rolls is considerable due to the higher volume of roll separating force. Owing to this kind of elastic deformation during rolling, the adjusted gap between the rolling dies is increased and this causes unexpected flow of material, shape and thickness. The purpose of this paper is to present a new approach for simulation of cold rolling of thin blades and studying the effect of elastic behavior of the machine structure as well as rolls deflection on the material flow and roll separating force.

In this paper, the process has been investigated using experimental test and simulation by introducing a new approach in a decision‐making flowchart. Instead of simulating of the entire system structure, a couple of virtual deformable rolls are suggested. The specifications of these rolls are selected to behave elastically during rolling same as whole roll stand. In addition, the thickness values are compared in both experiment and simulation. Also, the roll separating force is compared with and without using this approach.

A decision‐making algorithm has been presented that can be used to study the process. This finding provides the basis to investigate the effect of elastic deformation of machine structure and rolls on dimensional accuracy and roll force.

Result of this work can promote the position of simulation of the thin rolled sections to an extent more compatible with reality. For instance, the amount of increased gap between two dies during rolling can be estimated accurately. Also the influence of this gap on final blade thickness and the roll force and on the roll torque can be investigated by this approach.

The purpose of this study/paper is regarding analysis of electrical discontinuity in penultimate layer of a few batches of Multilayer Boards (MLB) fabricated and supplied by a vendor. The ever-increasing demand of miniaturization in launch vehicle and spacecraft electronics systems has led to the usage of multilayer printed circuit boards (PCBs) for realizing high-performance electronics circuitry. Multilayer boards (MLBs) fabricated by qualified agencies based on the customer requirement are being used in the critical launch vehicle/spacecraft systems after evaluating the preliminary test results supplied by the vendor. However, a few batches of MLBs fabricated and supplied by a particular vendor (“A”) showed a discontinuity problem in a few PCB tracks connected by soldering pads. As these MLBs are part of Flight critical systems of both launch vehicle and spacecraft, a malfunction in the board may lead to fatal errors during fight or on-orbit, thereby jeopardizing the mission.

A systematic approach was followed to have a thorough understanding of the problem, and major tests such as inspection, continuity measurement, microsection of the plated through hole (PTH) and Scanning Electron Microscopy–Energy Dispersive X-ray Analysis tests were conducted on identified test boards based on Ishikawa model. Emphasis was given for horizontal microsection, as it has got a clear edge in detecting defects at any point of PTH barrel to inner-layer copper interface.

Systematic testing and evaluation on specimen revealed the presence of unwanted material at the bonding area of inner-layer copper and PTH copper due to inadequate fabrication process. The un-cleaned epoxy materials present at the bonding area creates a weak bond between barrel and inner-layer copper. Electrical strength of the MLB is the strength of this link. This weaker interconnection leads to electrical discontinuity of inner-layer tracks.

MLBs are part of Flight critical systems of both Launch Vehicle and Spacecraft; a malfunction in the board may lead to fatal errors during fight or on-orbit, thereby jeopardizing the mission. Case study of an original failure observed in MLBs helped to achieve normal functioning of systems and avoided failures at later stage of mission.