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This paper aims to study the effect of elevated temperature on the compression behaviour of carbon fibre polyphenylene sulphide (CF/PPS) laminates notched and unnotched specimens made by film stacking method (FSM).

The surface of CF was coated with a silane coupling agent to form an effective transition layer with PPS, so as to enhance the interfacial interaction between CF and PPS. Considering the influence of fabrication pressure, forming temperature and cooling rate on the properties of laminates to obtain a reasonable preparation process. Conducting a compressive experiment of notched and unnotched specimens at different temperatures, which failure modes were examined by scanning electron microscope and stereo microscope.

The experimental observations highlight that with the increase of temperature, the transition failure mode from fibre broken to kink-band appeared in unnotched specimens, which were closely attributed to the matrix state. The notched specimens appeared more complex failure mode, which can be attributed to the joint effect of temperature and opening hole.

A simple way of FSM for composite material laminates has been developed by using woven CF and PPS films.

The outcome of this study will help to understand the compression response mechanism of composite materials made by FSM at different temperature.

The study aims to review the literatures on the effect of fiber length on the mechanical response of natural fiber composite will help the researchers to know about the perspective of the various natural fibers in making of composite concerning fiber length. The review summarized the work of the other researchers, thereby unambiguously précised suitability of a specific natural fiber for a matrix in use. Thus, one can identify the use of the same fibers–matrix combination to obtain composites with different properties with the control of fiber/matrix interface.

The review work proposes a new kind of diagrammatic representation that expresses the influence of fiber length. This work has not been explored before in this specific format. The chronology of work may help to select natural fibers for use in composites for a specific matrix.

The length of the fiber perception in terms of “critical” length decides the need for pre-treatment process of natural fiber to improve shear stress at the interface for various matrices.

The current review paper attempts to shed light on the association between the fiber length of natural fiber and the mechanical response of natural fiber composite. Moreover, it probes the concepts of critical fiber length as a persuadable factor.

THE generic term “reprographic” is intended to cover all the methods of making copies or reproductions and also the equipment related to these processes. The steady growth of all these methods has resulted in a close relationship between them, so that it is now almost impossible to refer to one without the other, especially where economics are being considered.

This paper aims to improve the load capacity of gas foil thrust bearing (GFTB) and to introduce and study a novel bearing with stacked bump foils.

For the proposed novel GFTB supported by stacked foils, some bump-type gaskets with several partial arches are inserted below the regular bump foil, and the height of each arch can be made differently. These features make the bump foil thickness and height gradually increase, which can bring enhanced support stiffness and convergent film at the trailing edge. Based on a new nonlinear bump stiffness model considering bump rounding and friction force, the finite element and finite difference method were used to solve the coupling Reynolds equation, energy equation and foil deformation equation. Finally, the structural stiffness and static characteristics of the novel GFTB were gained and compared with the traditional bearing.

The novel GFTB has an additional convergence effect in the parallel section, which improves the static performance of bearing. The bearing capacity, friction moment, power loss and temperature rise of the novel GFTB are all higher than those of the traditional bearing, and the static characteristics are related to the parameters of stacked bump foils.

The stacked bump foils bring a fundamental enhancement on the load capacity of GFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0449/

The purpose of this paper is to find an optimized thin-film amorphous silicon solar cell design by numerically optimizing the light trapping efficiency of a pyramid-structured back-reflector using a frequency-domain finite element Maxwell solver. For this purpose short circuit current densities and absorption spectra within the investigated solar cell model are systematically analyzed. Furthermore, the authors employ a topology simulation method to accurately predict the material layer interfaces within the investigated solar cell model. The method simulates the chemical vapor deposition (CVD) process that is typically used to fabricate thin-film solar cells by combining a ballistic transport and reaction model (BTRM) with a level-set method in an iterative approach. Predicted solar cell models are far more realistic compared to solar cell models created assuming conformal material growth. The purpose of the topology simulation method is to increase the accuracy of thin-film solar cell models in order to facilitate highly accurate simulation results in solar cell design optimizations.

The authors perform numeric optimizations using a frequency domain finite element Maxwell solver. Topology simulations are carried out using a BTRM combined with a level-set method in an iterative fashion.

The simulation results reveal that the employed pyramid structured back-reflectors effectively increase the light path in the absorber mainly by exciting photonic waveguide modes. In using the optimization approach, the authors have identified solar cell models with cell periodicities around 480 nm and pyramid base widths around 450 nm to yield the highest short circuit current densities. Compared to equivalent solar cell models with flat back-reflectors, computed short circuit current densities are significantly increased. Furthermore, the paper finds that the solar cell models computed using the topology simulation approach represent a far more realistic approximation to a real solar cell stack compared to solar cell models computed by a conformal material growth assumption.

So far in the topology simulation approach the authors assume CVD as the material deposition process for all material layers. However, during the fabrication process sputtering (i.e. physical vapor deposition) will be employed for the Al:ZnO and ITO layers. In the framework of this ongoing research project the authors will extend the topology simulation approach to take the different material deposition processes into account. The differences in predicted material interfaces will presumably be only minor compared to the results shown here and certainly be insignificant relative to the differences the authors observe for solar cell models computed assuming conformal material growth.

The authors systematically investigate and optimize the light trapping efficiency of a pyramid nano-structured back-reflector using rigorous electromagnetic field computations with a 3D finite element Maxwell solver. To the authors’ knowledge such an investigation has not been carried out yet in the solar cell research literature. The topology simulation approach (to the best of the authors’ knowledge) has previously not been applied to the modelling of solar cells. Typically a conformal layer growth assumption is used instead.

TWO factories were built recently and production was started in them. Both were engaged on similar types of work and time study was applied in both. In one, the time study engineer insisted on determining and applying “permanent” standards although the production flow was intermittent. In the other the time study engineer insisted on setting “temporary” standards because production was intermittent. In both factories incentives were paid based upon the standards fixed.

This paper aims to study the influence of the Cu-Al₂O₃ film-coated Cu substrate as a thermal interface material (TIM) on the thermal and optical behaviour of the light-emitting diode (LED) package and the annealing effect on the thermal and optical properties of the films.

A layer-stacking technique has been used to deposit the Cu-Al₂O₃ films by means of magnetron sputtering, and the annealing process was conducted on the synthesized films.

In this paper, it was found that the un-annealed Cu-Al₂O₃–coated Cu substrate exhibited low value of thermal resistance compared to the bare Cu substrate and to the results of previous works. Also the annealing effect does not have a significant impact on the changes of properties of the films.

It is deduced that the increase of the Cu layer thickness can further improve the thermal properties of the deposited film, which can reduce the thermal resistance of the package in system-level analysis.

The paper suggested that the Cu-Al₂O₃–coated Cu substrate can be used as alternative TIM for the thermal management of the application of LEDs.

In this paper, the Cu substrate has been used as the substrate for the Cu-Al₂O₃ films, as the Cu substrate has higher thermal conductivity compared to the Al substrate as shown in previous work.

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined.

Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials.

HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA.

The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages.

It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.

The older Man. Employers are advised to judge a man on his ability and not his age in a report of the National Advisory Committee on the Employment of Older Men and Women. Acceptance of the principle that greater employment of older people should be encouraged is urged by the report which says that the increases in the proportion of older people will make greater production necessary for their maintenance and that if they retire their contribution to production will be lost. Again, it is suggested that with improved working conditions there may be a capacity for a longer working life.

This paper aims to realize the vertical interconnection in 3D radio frequency (RF) circuit by coaxial transitions with broad working bandwidth and small signal loss.

An advanced packaging method, 12-inch wafer-level through-mold-via (TMV) additive manufacturing, is used to fabricate a 3D resin-based coaxial transition with a continuous ground wall (named resin-coaxial transition). Designation and simulation are implemented to ensure the application universality and fabrication feasibility. The outer radius R of coaxial transition is optimized by designing and fabricating three samples.

The fabricated coaxial transition possesses an inner radius of 40 µm and a length of 200 µm. The optimized sample with an outer radius R of 155 µm exhibits S11 < –10 dB and S21 > –1.3 dB at 10–110 GHz and the smallest insertion loss (S21 = 0.83 dB at 77 GHz) among the samples. Moreover, the S21 of the samples increases at 58.4–90.1 GHz, indicating a broad and suitable working bandwidth.

The wafer-level TMV additive manufacturing method is applied to fabricate coaxial transitions for the first time. The fabricated resin-coaxial transitions show good performance up to the W-band. It may provide new strategies for novel designing and fabricating methods of RF transitions.