Numerous Engineering Fields Research Articles

Investigation for impact behavior of acrylonitrile-butadiene-styrene amorphous thermoplastic

Acrylonitrile-Butadiene-Styrene (ABS) is an important terpolymer that find applications in numerous engineering fields due to its high impact resistance. Thereby, the experimental characterzation and numerical validation of its impact behavior is the main focus of this investigation. Impact tests were carried out using hemi-spherical impactor at three velocities of 4.43 m/s, 5.775 m/s and 6.264 m/s, respectively. The localized material change caused by microvoids was noticed near the impact zone on non-impacted surfaces for all impact velocities. The damage morphologies on the non-impacted surface for 4.43 m/s includes plastic deformation and crazes without any microvoids, whereas a combination of crazes and microvoids were discovered for other two velocities. Tensile tests at various strain rates, compression and shear tests were performed on ABS material at quasi-static conditions to utilize as an input to the SAMP-1 material model in impact simulations. The predicted impact histories and damage morphologies were compared with the experimental results.

A new time-frequency analysis method based on single mode function decomposition for offshore wind turbines

The Hilbert-Huang transform (HHT) has been widely applied and recognised as a powerful time-frequency analysis method for nonlinear and non-stationary signals in numerous engineering fields. One of its major challenges is that the HHT is frequently subject to mode mixing in the processing of practical signals such as those of offshore wind turbines, as the frequencies of offshore wind turbines are typically close and contaminated by noise. To address this issue, this paper proposes a new time-frequency analysis method based on single mode function (SMF) decomposition to overcome the mode mixing problem in the structural health monitoring (SHM) of offshore wind turbines. In this approach, the structural vibration signal is first decomposed into a set of window components using complex exponential decomposition. A state-space model is introduced in the signal decomposition to improve the numerical stability of the decomposition, and then a novel window-alignment strategy, named energy gridding, is proposed and the signals are constructed in the corresponding gridding. Furthermore, energy recollection is implemented in each gridding, and the reassembling of these components yields an SMF that is comparable to the intrinsic mode function (IMF) of the HHT, but with a significant improvement in terms of mode mixing. Four case studies are conducted to evaluate the performance of the proposed method. The first case attempts to detect three different frequencies in a simulated time-invariant signal. The second case attempts to test a synthesised signal with segmental time-varying frequencies (each segment contains three different frequencies components). The analysis results in these two cases indicate that mode mixing can be reduced by the proposed method. Furthermore, a synthesised signal with slowly varying frequencies is used. These analysis results demonstrate the effective suppression of non-relevant frequency components using SMF decomposition. In the third case, the experimental data from vortex-induced vibration (VIV) experiments sponsored by the Norwegian Deepwater Programme (NDP) are used to evaluate the proposed SMF decomposition for vibration mode identification. In the final case, field data acquired from an offshore wind turbine foundation and offshore wind turbine are analysed. The mode identification results obtained using SMF decomposition are compared with those produced by the HHT. The comparison demonstrates superior performance of the proposed method in identifying the vibration modes of the VIV experimental and field data.

Wavy water thin-film characteristics on horizontal plate using PLIF Experimental

Nonlinear Thin liquid film is commonly applied in numerous engineering fields, including the Passive Containment Cooling System of the nuclear power plant and steam dryer in the steam generator of nuclear power plants. The counter gas flow effect through a rectangular channel was inspected, the flow is motivated by the pressure gradient and shear gas stress while the gravity force does not influence the flow. Different flow rates of gas were set to different Reynolds numbers from 6950 to 34800 with influence on a different range of input water Reynolds number from 170 to 875 respectively. The data was collected at different sections from inlet flow until the separation section. The thickness of liquid film investigated using (PLIF) experiments. The thickness has been calculated via digital image processing and MATLAB code. Film thickness was obtained as a function of time and frequency. Results were analyzed using statistic tools such as property density function (PDF), fast Fourier transform (FFT), and power spectral density (PSD).

Enhanced numerical simulation of photocatalytic reactors with an improved solver for the radiative transfer equation

This work presents the enhanced numerical simulation of the radiation transport in three different types of photocatalytic reactor using a novel Discrete Ordinate Method model recently developed for the open-source Computational Fluid Dynamics (CFD) platform OpenFOAM. The photoreactors represent commonly used geometries and illumination sources in the field of heterogeneous photocatalysis: an annular reactor illuminated by a mercury fluorescent lamp, a tubular reactor coupled to a compound parabolic collector illuminated by sunlight, and a tubular reactor illuminated by LEDs. Simulations were carried out for different photocatalyst concentrations, considering absorption and anisotropic scattering, showing differences smaller than 2.4% with respect to the results obtained by commercial CFD software for systems with isotropic emission, such as fluorescent lamps. Moreover, the model was able to improve the simulation of solar reactors and dramatically outperformed the simulation of LED sources, due to the combined effect of quadrature rotation and cone-limit fitting for cone-shaped sources, as well as a LED-specific power-cosine light distribution. The developed model has been thoroughly validated and is now available to the open-source CFD community. It allows a comprehensive numerical simulation of radiation transport using any type of light source, with applications in numerous engineering fields where optical phenomena affect the performance of the process.

Investigation of Thermal Properties of Novel Phase Change Material Mixtures (Octadecane-Diamond) with Laser Flash Analysis

Abstract Phase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.

Analysis of a latent heat thermal energy storage unit with metal foam insert in both the HTF and PCM sides

Latent heat thermal energy storage (LHTES) systems using phase change material (PCM) have received significant research attention in numerous engineering fields. The transient heat transfer phenomenon inside a vertical LHTES unit is numerically investigated, with the paraffin as the PCM and water as the heat transfer fluid (HTF). As a performance enhancement technique, the metal foam insert is applied in both the HTF and PCM sides. The conjugate thermal model for the HTF/foam-wall-PCM/foam system is built, considering the non-equilibrium effect between the solid and fluid phases with two-temperature energy equation and the natural convection inside the PCM with Boussinesq approximation. The enthalpy-based method is employed to account for the solid-liquid phase change problem. The overall performance is compared with other three cases: no foam insert, foam insert in HTF side and foam insert in PCM side. Besides, parametric study is also conducted on the melting features, including the foam structural parameters and inlet conditions of HTF. The results show that foam insert in both sides accelerates the PCM melting effectively. The foam porosity and HTF inlet temperature play important roles in the overall heat transfer, whereas the pore density and HTF inlet velocity have limited effects on the melting rate. The findings can provide referential information for the design of a LHTES system.

Performance evaluation of a double-pipe heat exchanger with uniform and graded metal foams

Metal foam heat exchangers have attracted a great deal of interest in numerous engineering fields due to their superior thermal capabilities. In the present study, the heat transfer characteristics of a double-pipe heat exchanger with metal foam insert are numerically investigated. The Forchheimer-extended Darcy equation and the local thermal non-equilibrium (LTNE) model are used to predict the fluid and energy transports, respectively. Thermal resistance of the interface solid wall is considered, while the porous-solid boundary follows the continuity principles. The commercial software FLUENT with specific user defined functions (UDFs) is adopted to implement the simulation. Configurations with uniform foam structure are firstly used to analyze the effects of flow arrangement, foam structural parameters (porosity and pore density) and thermal conductivity on the heat exchanger effectiveness and total pressure drop. Then, graded foam structure along the radius is proposed to further make use of the heat transfer potential of metal foam. The overall thermal performance with increasing and decreasing arrangements of porosity and pore density is assessed. The results indicate that the counter flow shows good performance, with 37.5% higher than the parallel flow in effectiveness. The effectiveness and total pressure drop present monotonic variation with the foam structural parameters for the uniform designs, while maximum performance factor occurs at 15 PPI. The effectiveness has a reduction after gradual increase to a peak 0.89 with the increasing of thermal conductivity of foam matrix. For the designs of graded foam structure, using lower porosity and small pore density at both side of the inner pipe wall shows better overall performance with the performance factors of 4.41 and 4.54.

Adaptive differential evolution with a Lagrange interpolation argument algorithm

Differential evolution (DE) is a simple yet powerful evolutionary algorithm that has been used to solve various complex optimization problems in numerous engineering fields. However, DE has some problems, such as premature convergence and sensitivity to parameter settings. To improve the performance of DE and extend its application, an adaptive differential evolution with the Lagrange interpolation argument algorithm (ADELI) is proposed in this paper. To accelerate the convergence speed of DE, a local search with Lagrange interpolation (LSLI) is introduced into DE. LSLI performs a local search in the neighborhood of the best individual in the current generation to enhance the exploitation capability of DE. Meanwhile, an adaptive argument strategy is presented to adaptively determine whether to use LSLI in terms of its performance in the previous generation, which can balance the global exploration capability and the local exploitation capability of ADELI. To verify the feasibility and effectiveness of ADELI, 30 test functions in the CEC 2014 benchmark sets with different dimensions were simulated. Moreover, a path synthesis problem was also optimized. The results demonstrated that ADELI considerably outperforms other EAs in most functions and obtains the most accurate solution among the compared algorithms in the application of path generation.

Characterization of skeletal muscle passive mechanical properties by novel micro-force sensor and tissue micro-dissection by femtosecond laser ablation

Important aspects of the passive mechanical properties of skeletal muscle tissue are not yet fully understood. The prediction of passive tissue response to mechanical stimulation is relevant to numerous fields of engineering and research. This study aims to investigate the extracellular matrix contribution on a microscopic scale. Here, a novel micro-force sensor technology is applied to the testing of biological materials and is shown to reliably recognize the anisotropy of the fibrous muscular tissue in small samples. The preparation of even smaller tissue samples with microscopic dimensions by femtosecond-laser ablation has been studied with respect to laser parameters and their influence on thermal damage in the tissue and structure-fidelity. The ablation strategy has been found to have an impact on tissue degeneration. A suitable pulse energy range has been identified for the chosen ablation strategy.

Applying the Mahalanobis–Taguchi System to Improve Tablet PC Production Processes

Product testing is a critical step in tablet PC manufacturing processes. Purchases of testing equipment and on-site testing personnel increase overall manufacturing costs. In addition, to improve manufacturing capabilities, manufacturers must also produce products with higher quality and at a lower cost than their competitors if they are to attract consumers and gain a competitive edge in their industry. The Mahalanobis–Taguchi System (MTS) is a novel technique proposed by Genichi Taguchi for performing diagnoses and forecasting with multivariate data. The MTS can be used to select important factors and has been applied in numerous engineering fields to improve product and process quality. In the present study, the MTS, logistic regression, and a neural network were used to improve the tablet PC product testing process. The results indicated that the MTS attained 98% predictive power after insignificant test items were eliminated. The MTS performance was superior to those of the conventional logistic regression and neural network, which attained 93.3% and 94.7% predictive power, respectively. After the testing process was improved using the MTS, the number of test items in the tablet PC product testing process was reduced from 56 to 14. This facilitated the development of more stable test site configurations and effectively reduced the testing time, number of testers required, and equipment costs.

Identification of equivalent mechanical properties for unreinforced masonry walls

Transverse vibrations of beams are an interesting topic for numerous engineering fields. The equations of motion develop under various assumptions and associate a frequency equation. This paper expresses the frequency equation for two specific models, using the Timoshenko beam theory. The first model is a typical cantilever beam with an additional mass attached to the free end. The second model considers a beam partially clamped at the base and with an elastic connection of the additional mass to the free end. The relevance of the used theory is discussed and the importance of each term of the equation is studied. These models find applications in unreinforced masonry. They are indeed fitted to identify, from white noise tests, equivalent mechanical properties of unreinforced load-bearing clay masonry walls including soundproofing devices in the perspective of modelling these elements with a macro-scale approach. Discrepancies with respect to current standards are underscored.

Identification of equivalent mechanical properties for unreinforced masonry walls

Transverse vibrations of beams are an interesting topic for numerous engineering fields. The equations of motion develop under various assumptions and associate a frequency equation. This paper expresses the frequency equation for two specific models, using the Timoshenko beam theory. The first model is a typical cantilever beam with an additional mass attached to the free end. The second model considers a beam partially clamped at the base and with an elastic connection of the additional mass to the free end. The relevance of the used theory is discussed and the importance of each term of the equation is studied. These models find applications in unreinforced masonry. They are indeed fitted to identify, from white noise tests, equivalent mechanical properties of unreinforced load-bearing clay masonry walls including soundproofing devices in the perspective of modelling these elements with a macro-scale approach. Discrepancies with respect to current standards are underscored.

A review of the application of acoustic emission technique in engineering

The use of acoustic emission (AE) technique for detecting and monitoring damages and the progress on damages in different structures is widely used and has earned a reputation as one of the most reliable and well-established technique in non-destructive testing (NDT). Acoustic Emission is a very efficient and effective technology used for fracture behavior and fatigue detection in metals, fiberglass, wood, composites, ceramics, concrete and plastics. It can also be used for detecting faults and pressure leaks in vessels, tanks, pipes, as well as for monitoring the progression of corrosion in welding. This paper reviews major research developments over the past few years in application of acoustic emission in numerous engineering fields, including manufacturing, civil, aerospace and material engineering.

Delivering the Infrastructure for Digital Building Regulations

The building industry uses numerous engineering standards, building codes, specifications, and regulations (henceforth, all are referred to as “regulations” for the purposes of brevity), and a diverse set of industry vocabularies to describe, assess, and deliver constructed facilities. These building regulations are available as hardcopy and searchable digital documents. Some building design software applications (e.g., building-energy analysis and fire-egress assessment) are available that include computer-interpretable representations of the logic and rules from relevant building regulations. As part of the expanding use of building information modeling and new types of software applications, building and regulatory stakeholders and their software suppliers are recognizing the value of combining building models with rule sets for multidomain analyses, optimization, and assessing regulatory compliance. The availability of validated representations of building regulations for use by model-checking applications will streamline and shorten the building process, reduce inefficiencies and errors in the process, and enable new capabilities for optimizing designs and for automating the regulations-compliance assessment process. There has been a significant amount of research on this topic, and some of these results have been published in this journal during the past three decades. There are now a number of very important initiatives [e.g., by Associated General Contractors of America (AGC); American Institute of Steel Construction (AISC); American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE); Fiatech: Industry Consortium to Advance Innovation (ICAI); International Code Council (ICC); National Institute of Building Sciences (NIBS); and the United States Army Corps of Engineers (USACE)] to develop standardized representational approaches for building regulations so that they can be applied and checked automatically against building information models and standardized data-exchange representations, such as the Industry Foundation Classes (IFCs). Numerous fields of engineering, particularly those that rely on interdisciplinary collaboration, are adopting vocabulary-management and ontologydevelopment software tools as part of the process of transitioning to computer-interpretable standards for engineering. Buildingsystems engineering, sustainable manufacturing (Lechevalier et al. 2013), and biomedical engineering are using these semantic tools to develop the needed infrastructure for a new generation of computer-interpretable engineering standards. With this editorial, we provide recommendations for broadening the support and coordination of these initiatives, which are needed and timely, and present a set of issues derived from research and prototyping that is related to development and industry deployment of formal computable representations of building regulations. We hope that these recommendations and deployment challenges will be taken up, either in the short-term or over the long-term, by everyone involved in the digitization of building regulations and the building industry, as we move to using building regulations as computer-interpretable resources for model-based engineering in the architecture, engineering, and construction (AEC) industry.

Measurement of Dislocation Density in Cold-Drawn Steel Wires by Means of X-Ray Bragg Profiles Analysis

Cold-drawn pearlitic steel wires are widely used in numerous engineering fields. One of the most powerful analysis methods on determining the dislocation character of this heavily cold worked material is to investigate the X–ray diffraction line-profile broadening. Fourier line–broadening analysis in steel wires with near eutectoid composition indicates that with cumulative true strains, the initial dislocation density of 6×1014m-2in the rods increases at least one magnitude in wires. Up to 1.5×1016m-2of dislocation density is found in the ferrite lamella of wires with a true strain of 2.77.

Acoustic Distance Measurement Method Based on Phase Interference Using Calibration and Whitening Processing in Real Environments

Distance to target is fundamental and very important information in numerous engineering fields. Many distance measurement methods using sound use the time delay of a reflected wave, which is measured in reference to the transmitted wave. This method, however, cannot measure short distances because the transmitted wave, which has not attenuated sufficiently by the time the reflected waves are received, suppresses the reflected waves for short distances. Therefore, we proposed an acoustic distance measurement method based on the interference between the transmitted wave and the reflected waves, which can measure distance in a short range. The proposed method requires a cancellation processing for background components due to the spectrum of the transmitted wave and the transfer function of the measurement system in real environments. We refer to this processing as background components cancellation processing (BGCCP). We proposed BGCCP based on subtraction or whitening. However, the proposed method had a limitation with respect to the transmitted wave or additive noise in real environments. In the present paper, we propose an acoustic distance measurement method based on the new BGCCP. In the new BGCCP, we use the calibration of a real measurement system and the whitening processing of the transmitted wave and introduce the concept of the cepstrum to the proposed method in order to achieve robustness. Although the conventional BGCCP requires the recording of the transmitted wave under the condition without targets, the new BGCCP does not have this requirement. Finally, we confirmed the effectiveness of the proposed method through experiments in real environments. As a result, the proposed method was confirmed to be valid and effective, even in noisy environments.

On the formation of vacancies in α-ferrite of a heavily cold-drawn pearlitic steel wire

Cold-drawn pearlitic steel wires are widely used in numerous engineering fields. Combining X-ray line profile analysis and positron annihilation spectroscopy methods, up to 10−5–10−4 vacancies were found in α-ferrite of a cold-drawn pearlitic steel wire with a true strain of e = 3. The formation of deformation-induced vacancies in α-ferrite of cold-drawn pearlitic steel wire was quantitatively testified.

Guidelines And Advice For Successful Publication Provided By Journal Editors

Journal publication is an important indicator of research productivity for individual researchers, as well as academic institutions. However, for novice faculty members, the publication process can appear equivocal and daunting. If the academic does not actively engage themselves early in this process, then her or his career becomes an uphill (and sometimes insurmountable) battle. To assist the young academic, this study, sponsored by the National Science Foundation ADVANCE program, surveys journal editors representing numerous engineering fields. A 19-question web survey was e-mailed to 121 journal editors representing numerous engineering fields. Utilizing the ISI journal citation reports service, journal editors spanning aerospace, chemical, civil, environmental, industrial, and mechanical engineering disciplines were selected for initial contact. Of the 121 editors contacted, 40 usable responses (or a response rate of 33%) were aggregated for this study. The survey responses were used to quantify publication timelines and acceptance rates and ascertain journal policies, advice for successful publishing, and gender differences.

Publication process for engineers

Journal publication is an important indicator of research productivity for individual researchers as well as academic institutions. However, for young faculty members the publication process can appear equivocal and daunting. If the academic does not actively engage themselves early in this process, then her or his career becomes an uphill (and sometimes insurmountable) battle. To assist the young academic, this study, sponsored by the National Science Foundation ADVANCE program, surveys journal editors representing numerous engineering fields. The survey attempts to quantify publication timelines and acceptance rates, and ascertain journal policies, advice for successful publishing, and gender differences. Key words: Engineering education, publications, survey.