bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneous sensor fusion based on Copula theory and importance sampling
Authors: Lu Kelin , Sun Changyin , Fu Qien , Zhu Qian
Published: June 2019

This study deals with the problem of heterogeneous sensor fusion based on Copula theory and importance sampling. The proposed fusion algorithm is grounded on Copula statistical modelling and Bayesian probabilistic theory. The distinctive advantage of this Copula‐based methodology is that it formulates the internal dependency between the local sensors' data, which is usually unknown but essential for accurate track fusion. To this end, a joint distribution of the local sensors' observations is constructed based on Copula functions, and the corresponding fusion rule is derived with a specific correlation term. In addition, a Monte–Carlo importance sampling technique is adopted to improve the computational efficiency by drawing less random samples from the local estimates to be fused. After that, a procedure of Kernel density estimation is applied to learn a Gaussian approximation of the fused density. In the end, extensive Monte–Carlo simulations are conducted to evaluate the proposed sensor fusion method in a distributed target‐tracking scenario.
Exploring the damping of Alfvén waves along a long off-limb coronal loop, up to 1.4 R⊙
Authors: Gupta G. R. , Del Zanna G. , Mason H. E.
Published: July 2019

The Alfvén wave energy flux in the corona can be explored using the electron density and velocity amplitude of the waves. The velocity amplitude of Alfvén waves can be obtained from the non-thermal velocity of spectral line profiles. Previous calculations of the Alfvén wave energy flux with height in active regions and polar coronal holes have provided evidence for the damping of Alfvén waves with height. We present off-limb Hinode Extreme-ultraviolet Imaging Spectrometer (EIS) observations of a long coronal loop up to 1.4 R⊙. We obtained the electron density along the loop and found the loop to be almost in hydrostatic equilibrium. We obtained the temperature using the emission measure-loci (EM-loci) method and found the loop to be isothermal across, as well as along, the loop with a temperature of about 1.37 MK. We significantly improve the estimate of non-thermal velocities over previous studies by using the estimated ion (equal to electron) temperature. Estimates of electron densities are improved using the significant updates of the CHIANTI v.8 atomic data. More accurate measurements of propagating Alfvén wave energy along the coronal loop and its damping are presented up to distances of 1.4 R⊙, further than have been previously explored. The Alfvén wave energy flux obtained could contribute to a significant part of the coronal losses due to radiation along the loop.
Runaways and shells around the CMa OB1 association
Authors: Fernandes B. , Montmerle T. , Santos-Silva T. , Gregorio-Hetem J.
Published: July 2019

Context. The origin of the arc-shaped Sh 2-296 nebula is still unclear. Mainly due to its morphology, the nebula has been suggested to be a 0.5 Myr old supernova remnant (SNR) that could be inducing star formation in the CMa OB1 association. This means that the region might be an excellent laboratory for investigating the influence of massive stars on their surroundings.

Aims. We aim to show for the first time that the nebula is part of a large shell-like structure, which we have designated the “CMa shell”, enclosing a bubble created by successive supernova (SN) explosions. We identify three runaway stars, associated with bow-shock structures, in the direction of the CMa shell, and we investigate the possibility that they have originated in the center of the shell.

Methods. By analyzing images of the CMa OB1 association at several wavelengths, we clearly saw that the Sh 2-296 nebula is in fact part of a large structure that can be approximated by a large elliptical shell (with a diameter of ~60 pc). Using the recent Gaia DR2 astrometric data, we traced back the path of the three runaway stars, in order to determine their original position in the past, with relation to the CMa shell. We also revised the heating and ionization of the Sh 2-296 nebula by comparing the photon budget provided by the O stars in the region with results from radio observations.

Results. We find that the runaway stars have likely been ejected from a Trapezium-like progenitor cluster on three successive SN explosions that occurred ~6, ~2 and ~1 Myr ago. We also show that the few late-type O stars in the region cannot explain the ionization of the Sh 2-296 nebula, and that other mechanisms need to be at work.

Conclusions. We argue that although we now have evidence for several SNe events in the CMa OB1 association, the SNe probably played a minor role in triggering star formation in these clouds. In contrast, the CMa OB1 association as it is now likely testifies to the last stages of a star-forming region.
Surgical Management of Complex Enteric Fistulas in Crohn's Disease
Authors: de Campos-Lobato Luiz Felipe , Kiran Ravi P.
Published: July 2019

Crohn's disease is a chronic, inflammatory bowel condition that can affect the entire digestive tract and in many cases lead to enteric fistula formation. The management of enteric fistulas can be challenging and often requires a multidisciplinary approach.
Heterogeneity of Hepatocellular Carcinoma on Imaging
Authors: Rimola Jordi
Published: July 2019

Tumor heterogeneity in hepatocellular carcinomas (HCC) occurs at different levels. On conventional imaging modalities, the spectrum of tumor heterogeneity is evident in the dynamic enhancement pattern, where the characteristic wash-in and wash-out is present in only 60% of small HCCs. In larger HCCs, heterogeneity within the tumor, known as the mosaic pattern, can reflect the presence of different grades of HCC differentiation. The advent of functional imaging techniques has not improved the diagnostic sensitivity of imaging techniques for the diagnosis of HCC. However, the combination of conventional and functional imaging techniques potentially allows the identification of heterogeneity in tumor vascularity, cellularity, and molecular expression.
Engineering 3D hybrid electrode composed of ceria nanoparticles embedded in nickel oxides for high-performance supercapacitors
Authors: Zhao Yuhui , Sun Dongshu , Xing Guoliang , Wei Maobin , Yang Jinghai , Wang Xinying , Wang Dandan
Published: July 2019

We report on the development of a facile and rational template-free method to engineer three-dimensional (3D) intact hybrid electrodes for high-performance pseudocapacitance supercapacitor (SC) applications. A unique half-cell scheme with ceria nanoparticles embedded in nickel oxide (i.e., NiO@CeO2) electrode is developed via an in situ solvothermal and annealed methodology. Owing to the hierarchical structure nature of NiO@CeO2 and the conductive 3D foamed nickel (FN) substrate characteristics, the resultant of 3D NiO@CeO2 hybrid electrodes exhibits excellent capacity performance (1250.44 F g−1 at 1 A g−1) with a maximal energy density of 203 W h kg−1 at 2.21 kW kg−1. The enhanced specific capacitance is attributed to the coexisting oxygen vacancies and the nanoscale effect in the developed 3D NiO@CeO2 architecture, facilitating the charge transfer rate between electrodes and electrolyte interfaces with elaborating high electrical conductivity. Moreover, in the 2000 cycles evaluation process, a high-power specific capacitance is demonstrated in the first few cycles of charge and discharge processes with 88% capacitive retention rate, illustrating that the developed electrodes could be considered a primary promising candidate for sustainable energy storage and conversion supercapacitor applications.
Practical approaches to designing and fabricating flat lenses
Authors: Sedaghat Morteza , Nayyeri Vahid , Soleimani Mohammad , Ramahi Omar M.
Published: July 2019

This work presents two approaches to design and implement three-dimensional (3D) graded index (GRIN) flat lenses consisting of concentric annular segments. Generally, the design of GRIN flat lenses calls for segments with very specific tailored permittivity which makes the realization of the lens challenging. To meet this challenge, each segment of the lens is replaced with a three-layer structure consisting of two materials with a high and a low dielectric constant in such a way that the high permittivity layer is sandwiched between two low permittivity layers. By treating the lens segments as transmission lines and taking the effect of multiple reflections into account, the layer thicknesses are adjusted in such a way that the rays passing through different segments interfere constructively at a focal point. To further improve the focusing performance, a practical design approach is introduced in which each segment of the lens is made of a symmetric seven-layer structure using only two materials (alternating in arrangement) with a high and a low dielectric constant. This design provides the following features: (1) almost all of the incident power passes the lens without considerable reflection, (2) the lens provides a constructive interference of the incident wave at a focal point, and (3) the lens has the potential to be manufactured using available material and technology. Numerical examples are provided in which silica and silicon are utilized as low and high permittivity materials, respectively.
Compressive stress effect on the loss mechanism in a soft piezoelectric Pb(Zr,Ti)O3
Authors: Daneshpajooh H. , Choi M. , Park Y. , Scholehwar T. , Hennig E. , Uchino K.
Published: July 2019

High power piezoelectric devices are often subjected to external mechanical biases, in applications such as underwater transducers. While the performance of these devices under external pressure has been rather extensively studied, there is a lack of study on the loss mechanism in terms of three dielectric, elastic, and piezoelectric losses. Thus, in this paper, we study the mechanical bias stress dependence of the loss mechanism in a soft piezoelectric Pb(Zr,Ti)O3 (PZT) from a scientific viewpoint, using an equivalent circuit methodology based on the fundamental longitudinal mode. In order to measure the loss behavior, a modified bolt-clamped Langevin transducer was designed and optimized using finite element analysis in order to facilitate the analysis easier. We present the preliminary experimental part of our project on the design of the proposed structure/methodology, material creep behavior, stress relaxation, and uniform stress distribution, in order to minimize the experimental errors. We also introduce a six terminal equivalent circuit analysis in order to determine three losses in the PZT specimen. The resonance/antiresonance frequencies and quality factors showed monotonous increase under compressive stress. Loss factors for one PZT composition are reported in this paper to show the feasibility of our methodology for measuring the uniaxial compressive stress dependence.
Symmetry induced group consensus
Authors: Klickstein Isaac , Pecora Louis , Sorrentino Francesco
Published: July 2019

There has been substantial work studying consensus problems for which there is a single common final state, although there are many real-world complex networks for which the complete consensus may be undesirable. More recently, the concept of group consensus whereby subsets of nodes are chosen to reach a common final state distinct from others has been developed, but the methods tend to be independent of the underlying network topology. Here, an alternative type of group consensus is achieved for which nodes that are “symmetric” achieve a common final state. The dynamic behavior may be distinct between nodes that are not symmetric. We show how group consensus for heterogeneous linear agents can be achieved via a simple coupling protocol that exploits the topology of the network. We see that group consensus is possible on both stable and unstable trajectories. We observe and characterize the phenomenon of “isolated group consensus,” where one or more clusters may achieve group consensus while the other clusters do not.
Deep-level transient spectroscopy studies of electron and hole traps in n-type GaN homoepitaxial layers grown by quartz-free hydride-vapor-phase epitaxy
Authors: Kanegae Kazutaka , Fujikura Hajime , Otoki Yohei , Konno Taichiro , Yoshida Takehiro , Horita Masahiro , Kimoto Tsunenobu , Suda Jun
Published: July 2019

We studied deep levels in quartz-free hydride-vapor-phase epitaxy (QF-HVPE)-grown homoepitaxial n-type GaN layers within which three electron and eight hole traps were detected. The dominant electron and hole traps observed in the QF-HVPE-grown GaN layers were E3 (EC − 0.60 eV) and H1 (EV + 0.87 eV), respectively. We found that the E3 trap density of QF-HVPE-grown GaN (∼1014 cm−3) was comparable with that of MOVPE-grown GaN layers, whereas the H1 trap density of QF-HVPE-grown GaN (∼1014 cm−3) was much smaller than that of an MOVPE-grown GaN layer with a low-residual-carbon growth condition. A detailed analysis of the QF-HVPE-grown GaN layers revealed that the H1 trap density is almost equal to the carbon impurity concentration and other impurities that compensate the Si donors besides the carbon impurity were hardly detected in the QF-HVPE-grown GaN layers.
Quantum dynamics of a molecular emitter strongly coupled with surface plasmon polaritons: A macroscopic quantum electrodynamics approach
Authors: Wang Siwei , Scholes Gregory D. , Hsu Liang-Yan
Published: July 2019

We study a molecular emitter above a silver surface in the framework of macroscopic quantum electrodynamics and explore the population dynamics including non-Markovian effects. The theory we present is general for molecular fluorescence in the presence of dielectrics with any space-dependent, frequency-dependent, or complex dielectric functions. Furthermore, the proposed theory allows us to calculate the memory kernel of polaritons using computational electrodynamics packages. In the limit of a high vibration frequency, the different strengths of exciton-polariton couplings lead to distinct characteristics in the population dynamics, e.g., Franck-Condon-Rabi oscillation. (The frequency of Rabi oscillation is dependent on the Franck-Condon factor.) Additionally, in a specific condition, we derive a parameter-free formula that can be used to estimate the exciton-polariton coupling between a molecular emitter and a nanocavity, and the coupling estimated by our theory is in good agreement with the reported experimental results [Chikkaraddy et al., Nature 535, 127–130 (2016)].
Thermo-breathing vibration of carbon nanoscrolls
Authors: Hua Anping , Xue Yixuan , Liu Rumeng , Wei Ning , Zhao Junhua
Published: July 2019

In this study, the thermo-breathing vibration of carbon nanoscrolls (CNSs) is studied by molecular dynamics (MD) simulations and continuum modeling. The breathing vibration strongly depends on the competition between the cohesive energy among the graphene layers of CNSs and the bending energy of CNSs, where the explicit expressions for the total cohesive energy of CNSs are derived by using Gaussian quadrature based on van der Waals interlayer interactions. In particular, the interlayer amplitudes on the breathing vibration of CNSs at different temperatures are obtained by continuum modeling with the equipartition theorem. Checking against our MD simulations shows that the present theoretical model has high accuracy. The analytical solutions show that the temperatures have no effect on the nature frequency of CNSs, but have a great effect on the vibration amplitude of CNSs. The obtained results should be of great importance for understanding the thermo-mechanical vibration of nanosized devices.
Angle-resolved broadband ferromagnetic resonance apparatus enabled through a spring-loaded sample mounting manipulator
Authors: He Shikun , Qin Qing , Zhou Tiejun , Panagopoulos Christos
Published: July 2019

Broadband ferromagnetic resonance is a useful technique to determine the magnetic anisotropy and study the magnetization dynamics of magnetic thin films. We report a spring-loaded sample loading manipulator for reliable sample mounting and rotation. The manipulator enables maximum signal, enhances system stability, and is particularly useful for fully automated in-plane-field angle-resolved measurements. This angle-resolved broadband ferromagnetic resonance apparatus provides a viable method to study anisotropic damping and weak magnetic anisotropies, both vital for fundamental research and applications.
A modern maximum-likelihood theory for high-dimensional logistic regression
Authors: Sur Pragya , Candès Emmanuel J.
Published: July 2019

Significance

Logistic regression is a popular model in statistics and machine learning to fit binary outcomes and assess the statistical significance of explanatory variables. Here, the classical theory of maximum-likelihood (ML) estimation is used by most software packages to produce inference. In the now common setting where the number of explanatory variables is not negligible compared with the sample size, we show that classical theory leads to inferential conclusions that cannot be trusted. We develop a theory that provides expressions for the bias and variance of the ML estimate and characterizes the asymptotic distribution of the likelihood-ratio statistic under some assumptions regarding the distribution of the explanatory variables. This theory can be used to provide valid inference.
Motile curved bacteria are Pareto-optimal
Authors: Schuech Rudi , Hoehfurtner Tatjana , Smith David J. , Humphries Stuart
Published: July 2019

Significance

Bacteria exhibit a bewildering diversity of morphologies, but despite their impact on nearly all aspects of life, they are frequently classified into a few general categories, usually just “spheres” and “rods.” Curved-rod bacteria are one simple variation observed in many environments, particularly the ocean. However, why so many species have evolved this shape is unknown. We show that curvature can increase swimming efficiency, revealing a widely applicable selective advantage. Furthermore, we show that the distribution of cell lengths and curvatures observed across bacteria in nature is predicted by evolutionary trade-offs between three tasks influenced by shape: efficient swimming, the ability to detect chemical gradients, and reduced cost of cell construction. We therefore reveal shape as an important component of microbial fitness.
Direct detection of atmospheric atomic bromine leading to mercury and ozone depletion
Authors: Wang Siyuan , McNamara Stephen M. , Moore Christopher W. , Obrist Daniel , Steffen Alexandra , Shepson Paul B. , Staebler Ralf M. , Raso Angela R. W. , Pratt Kerri A.
Published: June 2019

Bromine atoms play a central role in atmospheric reactive halogen chemistry, depleting ozone and elemental mercury, thereby enhancing deposition of toxic mercury, particularly in the Arctic near-surface troposphere. However, direct bromine atom measurements have been missing to date, due to the lack of analytical capability with sufficient sensitivity for ambient measurements. Here we present direct atmospheric bromine atom measurements, conducted in the springtime Arctic. Measured bromine atom levels reached 14 parts per trillion (ppt, pmol mol−1; 4.2 × 108atoms per cm−3) and were up to 3–10 times higher than estimates using previous indirect measurements not considering the critical role of molecular bromine. Observed ozone and elemental mercury depletion rates are quantitatively explained by the measured bromine atoms, providing field validation of highly uncertain mercury chemistry. Following complete ozone depletion, elevated bromine concentrations are sustained by photochemical snowpack emissions of molecular bromine and nitrogen oxides, resulting in continued atmospheric mercury depletion. This study provides a breakthrough in quantitatively constraining bromine chemistry in the polar atmosphere, where this chemistry connects the rapidly changing surface to pollutant fate.
Optimal control strategies for inhibition of protein aggregation
Authors: Michaels Thomas C. T. , Weber Christoph A. , Mahadevan L.
Published: June 2019

Significance

A range of medical conditions, such as Alzheimer’s disease, Parkinson’s disease, and type II diabetes, are linked to protein aggregation. Thus, it is imperative to develop effective therapeutic strategies to combat protein aggregation. Here, we lay out a general approach for optimizing inhibition strategies based on small molecules that suppress nucleation or growth of aggregates. Our model reveals that the optimal timing of drug administration crucially depends on whether the compound inhibits primary nucleation, secondary nucleation, or the growth of aggregates. This approach could guide the rational design of therapeutic strategies to target protein aggregation diseases.
De novo design of symmetric ferredoxins that shuttle electrons in vivo
Authors: Mutter Andrew C. , Tyryshkin Alexei M. , Campbell Ian J. , Poudel Saroj , Bennett George N. , Silberg Jonathan J. , Nanda Vikas , Falkowski Paul G.
Published: July 2019

Significance

Early life is thought to have evolved from simple building blocks that were propagated through gene duplication events. A classic example is the small soluble iron-sulfur containing protein, bacterial ferredoxin, which is an asymmetric dimer, an essential component of many extant electron transfer chains and has ancient origins. To probe the theoretical gene duplication origins of bacterial ferredoxins, we designed a series of synthetic symmetric constructs. All designs bound two iron-sulfur clusters and were able to support electron transfer between a pair of oxidoreductases in vivo in
Escherichia coli
. Our results strongly suggest that simple, symmetric ancestral proteins probably evolved early in Earth’s history and can be engineered to facilitate functional electron transfer in synthetic metabolic pathways.
Epistasis between antibiotic tolerance, persistence, and resistance mutations
Authors: Levin-Reisman Irit , Brauner Asher , Ronin Irine , Balaban Nathalie Q.
Published: July 2019

Significance

The failure of antibiotic treatment is a major concern worldwide. Resistance is a main determinant in the survival of bacteria under antibiotics. However, it is often observed that bacteria become recalcitrant to antibiotics treatment, without developing resistance, a phenomenon termed “tolerance.” Here we explored the interactions between tolerance and resistance mutations, both experimentally and theoretically, under killing conditions. We find that tolerance and resistance mutations interact synergistically, a finding that may be important for the design of more potent treatments.
Personal narrative skills of Urdu speaking
preschoolers
Authors: Hamdani Saboor Zafar , Arshad Tehreem , Tarar Sharmeen Aslam , Kausar Rukhsana
Published: July 2019

The present study aimed to explore the personal narrative skills
of Urdu speaking preschoolers, aged between 4 and 5 years. The study also aimed
to investigate the gender differences in narrative skills, and relationship and
the predictive association between macro- and microstructure skills. A total of
80 preschoolers were recruited using two-stage sampling (convenience and
purposive). After screening the participants for intellectual functioning, three
personal narratives were collected from each participant. The results revealed
non-significant differences on the basis of age and gender. A significant
correlation was found between the macro- and microstructure skills in children.
NDW (number of different words), TNW (total number of words), and MLU (mean
length of utterance) were revealed as significant predictors of macrostructural
competencies in children. This was the first research that highlighted the
narrative skills of Urdu speaking preschoolers. Hence, the patterns identified
might help in extending the theory and research in this field.
Extraction and Stripping Behaviour Study on Gold Recovery from Printed Circuit Board
Authors: Jumain Jalil Mohd , Md Zaini Mohd Saufi , Suhada Azmi Intan , Farahanim Wan Shah Nik Nur
Published: July 2019

Single extraction was used to investigate the suitable condition parameters of temperature and agitation speed in extracting gold, Au (III) from printed circuit board (PCB). Extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA) was mixed with thiourea leaching solution. From the extraction system, the optimised conditions are the temperature of 45°C and the agitation speed of 300rpm and obtained 88% of percentage of extraction (%E). In order to enhance the recovery of Au(III), three samples underwent stripping process, the results from three samples which are sample 1,2 and 3 showed the percentage of stripping efficiency (%S) were 50.37%, 29.58% and 25.64% respectively. The results of FTIR showed the presence of C-H and C-O bond in waste cooking oil and after addition of D2EHPA into the diluent the P-O-H, P-O-C and O-H vibration band were appeared.
Torrefaction of biomass macroalga Ulva intestinalis using TGA
Authors: Mokhtar M F M , Munajat N F
Published: July 2019

The torrefaction of Malaysian marine biomass specie called Ulva intestinalis was studied using thermogravimetric analyser (TGA). The torrefaction temperature and residence time were varied in the range of 200 – 300 °C and 30 – 90 minutes, respectively. The chemical functional groups in the torrefied U. intestinalis were identified by Fourier transform infrared (FTIR). TGA results showed that the torrefaction temperature has a greater influence on the weight loss and changes in the U. intestinalis’s properties after the torrefaction as compared to the torrefaction time. The increased in fixed carbon (FC), and carbon (C) content and decreased in volatile matter (VM), moisture content (MC) and oxygen (O) with the severity of torrefaction reflects the improvement of calorific values for the torrefied U. intestinalis. Analysis of the FTIR showed that the torrefaction decreased the spectra intensity of the main functional groups (O-H, C=C, C-O and C-H) as a consequence of structural alteration within the biomass. The present findings may provide useful information for the development of industrial torrefaction processes to turn U. intestinalis into a carbon enrichment solid fuel.
Preparation and Characterization of Chromium Metal Organic Framework for Carbon Dioxide Adsorption
Authors: Chong K C , Lau W J , Lai S O , Thiam H S , Ismail A F
Published: July 2019

Air pollution is a widely discussed topic in both academic and industry sectors, especially in the developing countries. According to the risk assessment report from the Global Burden of Disease Study conducted in 2010, air pollution had caused 6.85 million deaths globally and out of 4.3 million from these numbers is attributed by the indoor air pollution. Government regulatory bodies in most of the countries impose strict regulatory on the CO2 limit in the indoor air condition. CO2 is captured by several methods such as solvent adsorption, physical adsorption, cryogenic fractionation and membrane system. Recently, metal organic frameworks (MOF) such as MIL-100(Cr) have been identified as attractive material for CO2 adsorption as it requires low energy consumption and relatively moderate production volume, if compared to the conventional gas adsorption techniques. These advantages have spurred much interest from industries and academics to speed up the commercial viability of the CO2adsorption by MOF. In this work, the effect of metal oxide loading on the CO2 absorption by chromium (III) chloride hexahydrate and trimesic acid were investigate. The fabricated MOF were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) to observe its surface morphology and composition. The SEM morphology suggested that Cr-TA-3 possesses highest surface area to volume ratio attributed to the formation of agglomerate of crystal rod structure. In this paper, CO2 gas adsorption was carried bythemogravimetricanalyzer (TGA). The gas adsorption result indicated Cr-TA-3 recorded the highest CO2 adsorption at 0.038 mmol/g. The results obtained from this study suggested that MOF fabricated by chromium (III) chloride hexahydrate and trimesic acid possesses the potential to be applied in CO2 absorption.
Development of 3D printer for functionally graded material using fused deposition modelling method
Authors: Tey J Y , Teh D , Yeo W H , Shak K P Y , Saw L H , Lee T S
Published: July 2019

3D printing employed in additive manufacturing, converts digital data based on a computer-aided design (CAD) model into an object by adding material layer by layer. Unlike subtractive manufacturing, complex geometries can be printed with minimal wastage. The additive manufacturing process for 3D printers features several types of technology ranging from fused deposition modelling (FDM), laser sintering, stereolithography and laser melting to binder jetting and others. However, these technologies are limited to process one material at a time, which poses a challenge to print functionally graded material (FGM). This difficulty can be overcome by offering a unique solution which is proposed in this paper - by applying FDM customized with an extrusion screw to incorporate mixing and blending of the polymer matrix and filler as a continuous process during printing. The intent of this technique is to ease the production of FGMs (which vary in mechanical, electrical and texture gradually over volume) by incorporating additional filler into the polymer matrix during printing. Therefore, it could enable users to design and produce FGMs in a single printing process. A unique controllable mixer design is embedded in the printer to allow users to process and mix up bi-materials by varying the mixing ratio of two materials as required during the printing process. Through programmable logic controller (PLC), the printer is able to map the variation in material properties and control the mixing ratio required to achieve functionally graded 3D material.
Improvement of acoustic water leak detection based on dual tree complex wavelet transform-correlation method
Authors: Ting L L , Tey J Y , Tan A C , King Y J , Faidz A R
Published: July 2019

Water leakage is one of the important agendas across the globe thus several effectual systems for leakage detection had been developed with the aim to improve sustainable use of water. Among the methods, acoustic leak detection technique had been proven as a promising approach to detect and localize leaks in water or gas pipeline. However, existence of noise in acoustic signals complicated the leak detection practices. Traditional de-noising methods like filtering and wavelet de-noising are not suitable for non-stationary and broadband acoustic signals. Therefore, Dual Tree Complex Wavelet Transform (DTCWT) is applied in this paper to reduce acoustic noise and decompose signals into several frequency bands. DTCWT decomposition is intended to resolve the problem encountered by the typical correlation-based leak localization method. Due to dispersive and frequency-dependent nature of wave propagation, correlation-based method normally assumes constant wave velocity which results in inaccurate leak source localization. In this paper, signal will be de-noised and decomposed by employing DTCWT. Wave velocity is evaluated based on the dominant frequency and dispersion curve. Then, time delay can be estimated via comparison study among cross correlation, CWT localization and convolution. CWT localization and convolution are proposed as new time-delay estimation method attributable to enhance localization accuracy. Experimental results validated that the proposed method, DTCWT-correlation outperforms other methods with a localization error of 4.67 %. Both CWT localization and convolution are also capable to pinpoint the location of leaks. Besides, leaking and non-leaking condition can be differentiated after multilevel decomposition of DTCWT.
Investigation of wax deposition prevention by using n-heptane for sustainable energy production from Fang oilfield
Authors: Min H M , Maneeintr K
Published: July 2019

Waxy crude oils are normally found in petroleum reservoirs. Crude oil from wax formation is one of the crucial problems for flow assurance of pipeline transportation in oil and gas production. This issue can commonly cause wax deposition problem and it has made huge amount of economic loses such as production, time and maintenance cost. Therefore, it is a critical aspect to deal with wax deposition for crude oil flow assurance, especially in cold climate surface region. Nowadays, there are many methods that have been applied to reduce the wax deposition. In general, three methods are commonly utilized, mechanical, thermal and chemical ones. Among them, the usage of chemicals is commonly used in field because they can be applied easily rather than other techniques. In this study, n-heptane is select to study the prevention the wax deposition because its property can reduce the pour point and wax deposit of crude oil. It is easily available as well. Therefore, the aim of this research is investigate the effects of temperature and different chemical concentration on pour point and wax deposition of crude oil at three different temperature ranging from 35 to 55 °C by applying cold finger method. Also, the pour point of crude oil is measured with different n-heptane concentrations by ASTM method. Moreover, the effect of different chemical concentrations on wax appearance temperature (WAT) is examined the temperature between from 80 °C to 40 °C with three different shear rates by viscometry method. From the results, it is reported that the total wax deposits from the cold finger depend on the amount of chemical concentration used. WAT with 20% n-heptane provides the highest performance for WAT reduction with 41 °C. Compared to 5%, 10% and 15% n-heptane concentration, WATs are reduced to 45 °C, 44 °C and 43 °C, respectively. For the pour point results, the higher amount of n-heptane concentration offers the higher reduction in pour point temperature and pour points are reduced significantly from original pour point at 36 °C to 34 °C, 30 °C, 26 °C and 22 °C with 5%, 10%, 15% and 20% n-heptane, respectively. It is also found that the amount of total wax deposits decrease when chemical concentrations increase. Moreover, the decline of temperature is found as one of the main factors to cause more wax deposition. There is a highest wax deposit reduction rate with 20% n-heptane at different temperatures compared to other concentration. The wax deposition is reduced over 50% for each concentration. Therefore, this result is useful for the application of wax deposition, pour point and WAT studies in the crude oil production with less damaging environment for sustainable energy production.
BIM-based Approach for Green Buildings in Malaysia
Authors: Khoshdelnezamiha G , Liew S C , Bong V N S , Ong D E L
Published: July 2019

The construction industry in Malaysia faces a number of complications in terms of managing project duration and budgeted cost. The recent technology trend has moved the industry towards adoption of Building Information modelling (BIM) as a mean to efficiently plan, design, build, manage and control projects. Since BIM is perceived as a holistic solution for integration of various project attributes, this research has hypothesised that additional objectives such as sustainability and green building design can simultaneously be achieved if appropriate BIM approach is implemented. The main scope of this research is to introduce a framework for integration of Malaysian Green Building Index (GBI) with existing Building Information Modelling (BIM) tools. The proposed GBI-BIM framework is made possible via the introduction of a set of supporting tools such as Revit Green Project Template (RGPT) and GBI Document Assessor that assist designers to automatically analyse and assess 56 out of 100 GBI points during the design stage.
Comprehensive analysis of active and passive daylighting towards power savings in an office room
Authors: Obianuju Onubogu Nneka , Chong Kok-Keong
Published: July 2019

A comprehensive method is presented to simulate illuminance distribution for two office room designs with same area of 7.8 m2 each: room 1 has a window whilst room 2 has no window. The integration of passive daylighting system and light emitting diodes (LEDs) is adopted for illuminating room 1, while the integration of active daylighting system and LED lighting is adopted for illuminating room 2. The effectiveness and power savings are analysed for the aforementioned two cases. The impact of using LED lighting to control the illuminance and light distribution (uniformity) of light is also studied. For both cases, simulation was performed for a selected day under three sky conditions: clear sky, mixed sky and overcast sky using a software called DIALux 4.13 to obtain the average illuminance in the rooms and the power saved via the use of active and passive daylighting systems. Results obtained showed that active and passive daylighting systems are both effective for power savings depending on the location of rooms and time of the day. Also, active daylighting system is more effective under clear sky, while passive daylighting system can be effective under clear or mixed sky.
Wireless Power Transfer Technology Using Resonant Technique
Authors: Yee Yong Ching , Fen Chen Kok
Published: July 2019

Wireless power transfer (WPT) is a kind of technology by transferring the electrical energy from a power source to an electrical load without the use of wire or conductor. Nowadays, electricity power is very important in our daily life. People use portable electronic devices to improve their routine work. The portable electronic devices are connected to power socket for their power supply. However, it is not convenient to people due to the length of the wire and they are unable to move far from the power socket. Therefore, the main objective of this project is to investigate a wireless power transfer technology using resonant technique. The proposed model was designed and pre-tested by Multisim. An efficient and compact wireless power transfer using resonant technique was proposed and a wireless power supply system for low power electronic devices was developed. The design of the system is to transfer the low power for electronic devices from transmitter to receiver coils. The input DC power is 12 V and the magnetic field passes through resonator and causes the energy to build up. As the result, the voltage and current of LED (acts as load) are 0.668 V and 0.01 mA respectively with the distance of 5 cm. In order to smoothen the peak voltages, a capacitor and a diode were used as a filter and rectifier respectively in the circuit. Resonance inductive coupling is widely used for mid-range transmission distance due to its simplicity in system design. The optimum distance for harvesting the highest voltage is 3.5 cm apart. The efficiency of power transmitted was 41.6 %. The transmission of power is only affected by the metal made component which is placed near to it. Wireless power transfer is convenient, reliable, low cost, safer and environmentally sound. In conclusion, the wireless power transfer using resonance induction coupling is more efficient if compared with inductive coupling and electromagnetic wave. The power can transfer with a longer distance and safely by using this technique.
Compatibilized recycled polymers/clay as a matrix for rice husk composites: mechanical and physical properties
Authors: Shan Chen Ruey , Ahmad Sahrim
Published: July 2019

The growing green technological trend towards waste utilization and cost reduction has gained the industrial attention in the use of agricultural waste as a value added filler material. This research addresses a simple fabrication of greenly bionanocomposites made from polyethylene (rHDPE), recycled polyethylene terephthalate (rPET), nanoclay and rice husk (RH), with and without ethylene-glycidyl methacrylate (E-GMA) or maleic anhydride polyethylene (MAPE) compatibilizer, using a two-step twin-screw extrusion followed by hot/cold pressing. Results showed the positive effect in elongation at break and impact strength upon the reinforcement of nanoclay with the aids of compatibilizer as compared to the neat polyolefin blend. By adding RH, the flexural properties were found to increase remarkably up to 3.6 times than the blend matrix. It was found that the addition of compatibilizer, especially E-GMA, lowered the water absorption and thickness swelling of bionanocomposites. Scanning electron microscopy confirmed the improved compatibility of nanoclay with polymer blend upon the addition of compatibilizer. It can be concluded that the synergy effects of hybrid reinforcements of rice husk fibre and nanoclay in the recycled polymer blend have achieved while maintaining environmental appeal.
Review on Numerical Simulations for Solidification & Melting of Nano-Enhanced Phase Change Materials (NEPCM)
Authors: Irwan M A M , Nor Azwadi C S , Asako Y
Published: July 2019

A review on numerical simulations performed for solidification and melting process of Nano-Enhanced Phase Change Materials (NEPCM) is reported. The studies were conducted to understand the factors influencing the outcome such as nanoparticle fraction in the mixture, nanoparticle size, boundary conditions imposed and container geometry. It was found that while most studies investigated particle fraction effect, very few was conducted on the effect of nanoparticle size and shape. The numerical models applied to simulate the numerical works were compared. Most researchers applied enthalpy-porosity formulation coupled with finite volume method to perform the simulations. Most models solved a single macroscale domain at each iteration by assuming NEPCM as a single-phase substance which resulted in no attempt to model it as a two-phase substance which requires multidomain approach. Such dilemma is avoided when mesoscale method (Lattice Boltzmann Method - LBM) is applied.
Low Grade Heat Power Generation using Thermoelectric Generator
Authors: Julaihie K , Abu Bakar R , Bhathal Singh B , Remeli M , Oberoi A
Published: July 2019

Over years, researches on power generation from low grade heat energy sources have been increasing rapidly as it will be beneficial towards environment, human lives and also for long term sustainability. Due to its biggest potential and advantages, thermoelectric generator has been reliably used to generate electricity. In this project, an experiment on power generation using thermoelectric generator by employing low grade heat (<150 °C) energy source was carried out. The main purpose of this project was to generate useful electricity using thermoelectric generator and to investigate the quality of heat exchanger in enhancing the performance of thermoelectric generator. A prototype heat exchanger was used to carry out this experiment. The heat exchanger was tested with varied hot and cold water supply to study the effect of temperature difference on the thermoelectric generators. For this project, the highest output power obtained was 0.98 W and the maximum efficiency was 1.91%.
Electrochemical performance of La0.6Sr0.4CoO3-δ cathode in air and wet air for BaCe0.54Zr0.36Y0.1O3-based proton-conducting solid oxide fuel cell
Authors: Abdul Samat Abdullah , Rao Somalu Mahendra , Muchtar Andanastuti , Osman Nafisah
Published: July 2019

Solid oxide fuel cell (SOFC) electrodes often suffer from degradation resulting from different contaminations such as water vapour from air during high-temperature operation. Thus, humidity-resistant electrode materials must be developed for SOFC application. In this work, La0.6Sr0.4CoO3-δ (LSC) material is prepared by sol-gel method and evaluated as a potential cathode to be operated with proton-conducting electrolyte of BaCe0.54Zr0.36Y0.1O3 (BCZY) at intermediate temperature (500 – 800 °C). An LSC|BCZY|LSC symmetrical cell is fabricated by screen printing an LSC cathode ink onto a BCZY electrolyte pellet. The electrochemical performance of the LSC cathode for the fabricated symmetrical cell in air and wet air is characterised using an electrochemical impedance spectroscopy (EIS) analyser. EIS results revealed that the area specific resistance value of the LSC cathode in wet air is lower than that in air at temperatures ranging from 600 °C (0.35 Ω cm2) to 800 °C (0.06 Ω cm2) with a low value of activation energy (0.70 eV). Hence, the LSC cathode exhibits better electrocatalytic activity and performance in wet air than in air. This work suggests that the LSC material meets the requirements for application as a cathode in intermediate-temperature proton-conducting SOFC based on BCZY electrolyte.
Performance analysis of a counter-flow indirect evaporative cooling system
Authors: Cui Xin , Jia Guosheng , Liu Yilin , Zhang Sicong , Jin Liwen , Meng Xiangzhao
Published: July 2019

A counter-flow regenerative indirect evaporative heat exchanger (RIEHX) was introduced and investigated. This paper aims to conduct an experimental study for the RIEHX to investigate the cooling performance under different operating conditions. The experimental prototype was able to adjust the inlet air flow rate and temperature. The thermal performance of the RIEHX was tested with variable inlet conditions. The experimental results have demonstrated that the supply air can be effectively cooled along the product air flow passages by transferring heat to the wet side of the RIEHX due to water evaporation. Under a constant inlet air velocity, the product air with a higher inlet temperature can obtain a larger temperature reduction. In addition, a lower air flow rate may enhance the cooling effect due to the increased contact duration between the air streams. The proposed system is able to improve the cooling effectiveness of the conventional plate-type indirect evaporative cooler.
Feasibility of Biohydrogen Purification from Carbon Dioxide Mixture via Integrated Microalgae-Membrane Contactor Towards Zero Carbon Emission
Authors: Izni Yusoff Izzati , Rohani Rosiah , Sobri Takriff Mohd
Published: July 2019

Biohydrogen (H2) mixed with carbon dioxide (CO2) produced from the fermentation of Palm Oil Mill Effluent (POME) could be a potential renewable energy source. However, an effective technique to treat both gases towards zero carbon emission has become a major concern. In this study, a new approach was introduced to treat H2/CO2 mixture from POME fermentation by an integrated microalgae-membrane contactor system. Polyvinylidine fluoride (PVDF) hollow fibre membrane used in the integrated membrane contactor system abled to give the highest purified H2% from mixed H2/CO2 in the microalgae liquid absorbent (Chlorella Vulgaris) (69.4%) followed by Bold Basal Medium (BBM) (59.1%) and distilled water (55.9%). This initial result showed that the microalgae possessed better ability to absorb CO2 into the liquid stream via the PVDF membrane contactor. Next, investigation on optimizing the system’s operational parameters using BBM as liquid absorbent showed the highest CO2 absorption flux and efficiency were obtained at initial solution pH of 10. Further investigation showed that the absorption efficiency was enhanced as the liquid flow rate increased up to 0.4 L/min and the gas flow rate was at 0.1 L/min. Upon utilizing 0.6 g/L microalgae, the purified H2% found to remarkably increase up to 83.2%. In conclusion, the use of the developed integrated microalgae-membrane contactor system to purify the bio-H2 from CO2 mixture is a promising alternative method for zero carbon emission especially in palm oil industry.
Maximum Demand Management: An overlooked energy saving opportunity in industries
Authors: Ayyappan Preethy , Kumar Jeyanandan , Kumar Venkiteswaran Vinod
Published: July 2019

Maximum demand management is always overlooked as an energy saving opportunity in industry. Maximum demand charge is part of total electricity charges of an Industrial energy tariff and contributes around 20% of the total electrical energy bill. An energy audit conducted in an Industry revealed an opportunity of reducing the total plant maximum demand of average from 2736 kW to 2220 kW saving up to RM 17,000 on an average/month. The paper briefs the process re-engineering and technologies that could be used in the plant to reduce up to 20% Maximum demand charges from the total electricity bill. This can bring in a significant saving with minimal investment and is sustainable.