bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of blood flow past distal arteriovenous-graft anastomosis with intimal hyperplasia
Authors: Zhu Luoding , Sakai Kaoru
Published: May 2021

Late-stage kidney disease patients have to rely on hemodialysis for the maintenance of their regular lives. Arteriovenous graft (AVG) is one of the commonly used devices for dialysis. However, this artificially created shunt may get clotted and eventually causes the dialysis to fail. The culprit behind the AVG clotting and failure is the intimal hyperplasia (IH), the gradual thickening of vein-wall in the vicinity of the blood vessel-graft conjunctions. The mechanism of IH is not well understood despite extensive studies. In this work, we investigate the effects of the IH development, including its location and severity on the flow and force fields in the distal AVG anastomosis using computational fluid dynamics. The stenosis due to IH is modeled in the shape of a Gaussian function with two free parameters. The blood is modeled as a viscous incompressible fluid, and the blood flow (pulsatile) is governed by the Navier–Stokes equations which are numerically solved by the lattice Boltzmann model (D3Q19). The fluid-structure interaction is modeled by the immersed boundary framework. Our computational results show that the IH severity has the most significant influences on the wall shear stress, wall-normal stress, and the axial oscillating index. The stenosis location and flow pulsatility do not have pronounced effects on flow and force fields. Our results indicate that the IH progression tends to exacerbate the disease and accelerate the closure of the vein lumen, and hence the dialysis failure.
Analyzing the vast coronavirus literature with CoronaCentral
Authors: Lever Jake , Altman Russ B.
Published: May 2021

The SARS-CoV-2 pandemic has caused a surge in research exploring all aspects of the virus and its effects on human health. The overwhelming publication rate means that researchers are unable to keep abreast of the literature. To ameliorate this, we present the CoronaCentral resource that uses machine learning to process the research literature on SARS-CoV-2 together with SARS-CoV and MERS-CoV. We categorize the literature into useful topics and article types and enable analysis of the contents, pace, and emphasis of research during the crisis with integration of Altmetric data. These topics include therapeutics, disease forecasting, as well as growing areas such as “long COVID” and studies of inequality. This resource, available at
https://coronacentral.ai
, is updated daily.
Preliminary Study on the Mechanisms of Ankle Injuries Under Falling and Impact Conditions Based on the THUMS Model
Authors: Li Zhengdong , Zhang Jianhua , Wang Jinming , Huang Ping , Zou Donghua , Chen Yijiu
Published: May 2021

Ankle injuries are common in forensic practice, which are mainly caused by falling and traffic accidents. Determining the mechanisms and manners of ankle injuries is a critical and challenging problem for forensic experts. The identification of the injury mechanism is still experience-based and strongly subjective. There also lacks systematic research in current practice. In our study, based on the widely used Total Human Model of Safety 4.0 (THUMS 4.0), we utilized the finite element (FE) method to simulate ankle injuries caused by falls from different heights (5 m, 10 m and 20 m) with different landing postures (natural posture, inversion, eversion, plantar-flexion and dorsi-flexion) and injuries caused by impacts from different directions (anterior-posterior, lateral-medial and posterior-anterior) with different speeds (10 m/s, 15 m/s and 20 m/s) at different sites (ankle and lower, middle and upper sections of leg). We compared the injury morphology and analyzed the mechanisms of ankle injuries. The results showed that falling causes a specific compression fracture of the distal tibia, while fractures of the tibia and fibula diaphysis and ligament injuries caused by falling from a lower height or inversion, planter flexion or dorsiflexion at a large angle are not distinguishable from the similar injury patterns caused by impact on the middle and upper segments of the leg. No obvious compression fracture of the tibia distal was caused by the impacts, whereas ligament injuries and avulsion fractures of the medial or lateral condyle and fractures of the diaphysis of the tibia and fibula were observed. Systematic studies will be helpful in reconstructing the ankle injury processes and analyzing the mechanisms in forensic practice, providing a deeper understanding of ankle injury mechanisms for forensic experts.
Tunable thermal conductivity of ternary alloy semiconductors from first-principles
Authors: De Santiago Francisco , Raya-Moreno Martí , Miranda Álvaro , Cruz-Irisson Miguel , Cartoixà Xavier , Rurali Riccardo
Published: May 2021

We compute the thermal conductivity, κ, of five representative III–V ternary alloys—namely In
x
Ga1 − x
As, GaAs1 − x
P
x
, InAs1 − x
Sb
x
, GaAs1 − x
N
x
, and GaP1 − x
N
x
—in the whole range of compositions, and in zincblende and wurtzite crystal phases, using a first-principles approach and solving the phonon Boltzmann transport equation beyond the relaxation time approximation. We discuss the tunability of the thermal conductivity with the composition of the alloy, reporting a steep decrease in the thermal conductivity, followed by a wide plateau and a steep increase common in systems with lattice disorder. We also test the approximation consisting in considering impurities at small values of x as bare mass defects, neglecting their chemical identity, and discuss its validity.
Efficiency improvement of P3CT-Na based MAPbI3 solar cells with a simple wetting process
Authors: Kassou Said , Wu Jia-Ren , Thakur Diksha , Chandel Anjali , Chiang Shou-En , Cheng Kai-Jen , Chen Sheng-Hui , Shen Ji-Lin , Chang Sheng Hsiung
Published: May 2021

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI3 solar cells can be increased from 14.94% to 17.46% with a wetting method before the spin-coating process of MAPbI3 precursor solutions. The effects of the wetting process on the surface, structural, optical and excitonic properties of MAPbI3 thin films are investigated by using the atomic-force microscopic images, x-ray diffraction patterns, transmittance spectra, photoluminescence spectra and Raman scattering spectra. The experimental results show that the wetting process of MAPbI3 precursor solution on top of the P3CT-Na/ITO/glass substrate can be used to manipulate the molecular packing structure of the P3CT-Na thin film, which determines the formation of MAPbI3 thin films.
Chiral phase transition and equation of state in chiral imbalance *
Authors: Wang Qing-Wu , Shi Chao , Zong Hong-Shi
Published: May 2021

The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical

potentials are naturally included by introducing vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In the proper-time scheme, the chiral phase transition is a crossover in the

plane. However, when

is incorporated, our study demonstrates that a first order phase transition may emerge. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relationship and tidal deformability of quark stars are calculated. The maximum mass and radius decrease as

increases. Our study also indicates that the vector and axial-vector channels exhibit an opposite influence on the equation of state.
Heavy ion induced charge exchange reactions: A preliminary study within the Constrained Molecular Dynamics model
Authors: Giuliani Gianluca
Published: May 2021

We present a preliminary study of charge exchange heavy ion induced reactions based on the constrained molecular dynamics (CoMD) model. The purpose is to test the capability of the model in predicting the occurrence of single charge exchange (SCE) and double charge exchange (DCE) exit channels for three different entrance channels at the same laboratory incident energy. The nuclear reaction dynamics and nuclear interaction within the CoMD approach are the only ingredients that have given, at this stage, promising results for SCE and DCE cross section calculations. The obtained results suggest an upgrade and possible future employment of the model for studies relating to the production of exotic nuclei through charge exchange reactions or DCE reactions and their connection with neutrinoless double beta decay.
Signature of the 27-day variation in hemispheric sunspot activity and asymmetry during 2010–2015
Authors: Singh Prithvi Raj , Saad Farid Ahmad Islam , Kumar Pant Tarun , Kumar Singh Abhay
Published: May 2021

In the present work, we study the time evolution, significance of the N-S asymmetry excesses presented as a function of the solar cycle and prominent rotational periods (∼27 d) separately for the northern and southern hemispheres. We have investigated short-term variations of the hemispheric solar activity (sunspot numbers and sunspot areas) during the time period 2010–2015, which covers the ascending and the maximum phase of solar cycle 24. We have implemented the Lomb-Scargle periodogram and continuous wavelet transform power spectrum techniques to study the time evolution and dominant rotational periods separately for the northern and southern hemispheres, and whole solar disk. Our results showed that the northern hemisphere exhibited longer solar synodic periods than the southern hemisphere, indicating that the northern hemisphere has a lower rotation rate. Moreover, the northern hemisphere was found to be dominant before transferring to the southern hemisphere during mid-2013. Also, the sunspot areas clearly demonstrated a two-peak structure of solar activity in the northern and southern hemispheres respectively during 2012 and 2014. The statistical significance of the southern hemisphere affirmed enhanced excess during the maximum phase of solar cycle 24.
Magnetic activity and orbital parameters of CC Com based on photometric data, LAMOST low- and medium-resolution spectra
Authors: Zhu Zhong-Zhong , Zhang Li-Yun , Meng Gang , Cheng Yao , Long Liu , Han Xianming L. , Pi Qing-Feng , Jiang Lin-Yan
Published: May 2021

In this paper, we present four sets of photometric V RI light curves, and several LAMOST low and medium resolution spectra of contact binary CC Com. We revised the orbital parameters by simultaneously combining with previously published radial velocity measurements using the Wilson-Devinney program. We used light curves at different observational times to obtain the starspot parameters. The values of the starspot radius are variable in short- and long-term scales, and their longitudes are stable. We updated the orbital period change of CC Com, and analyzed the periodic variation. The period of CC Com decreases at a rate of 4.66 (±0.20) × 10−11 d yr−1, which may be due to mass transfer from the secondary component to the primary component. The oscillation of its orbital period with a period of 17.18(0.08) years and amplitude of 0.0018(1) d may be caused by the light time effect (LITE) via a third body of 0.06 M
⊙ dwarf or magnetic activity cycle. Furthermore, we obtained one optical spectrum from the LAMOST survey, which gives the spectral type of CC Com as K7±2V. Strong emissions exist in the Hα, and Ca ii H&K lines in the observed spectrum, indicating strong chromospheric activity on CC Com. In the 12 LAMOST medium-resolution spectra, the EWs of Hα line are variable along the phase and time, which may be a plage or flare event.
An agile very low frequency radio spectrum explorer
Authors: Chen Lin-Jie , Yan Yi-Hua , Fan Qiu-Xiang , Geng Li-Hong , Bisoi Susanta Kumar
Published: May 2021

The very low frequency (VLF) regime below 30 MHz in the electromagnetic spectrum has presently been drawing global attention in radio astronomical research due to its potentially significant science outcomes exploring many unknown extragalactic sources, transients, and so on. However, the nontransparency of the Earth’s ionosphere, ionospheric distortion and artificial radio frequency interference (RFI) have made it difficult to detect the VLF celestial radio emission with ground-based instruments. A straightforward solution to overcome these problems is a space-based VLF radio telescope, just like the VLF radio instruments onboard the Chang’E-4 spacecraft. But building such a space telescope would be inevitably costly and technically challenging. The alternative approach would be then a ground-based VLF radio telescope. Particularly, in the period of post 2020 when the solar and terrestrial ionospheric activities are expected to be in a ‘calm’ state, it will provide us a good chance to perform VLF ground-based radio observations. Anticipating such an opportunity, we built an agile VLF radio spectrum explorer co-located with the currently operationalMingantu Spectra Radio Heliograph (MUSER). The instrument includes four antennas operating in the VLF frequency range 1–70 MHz. Along with them, we employ an eight-channel analog and digital receivers to amplify, digitize and process the radio signals received by the antennas. We present in the paper this VLF radio spectrum explorer and the instrument will be useful for celestial studies of VLF radio emissions.
Trend of Urbanization Rate in China Various Regions
Authors: Duan Lingyun , Liu Ziyuan , Yu Wen , Chen Wei , Jin Dongyan , Sun Suhua , Dai Ruixi
Published: May 2021

Urbanization is a key part of achieving a overall well-off society in it’s decisive stage. Accurately predicting the developing trend of urbanization rate has important practical significance for relevant departments to make strategic decisions. This article uses Stata software and the relevant data released by Data Center of the National Bureau of Statistics, selects the urbanization rate time series data of 31 provinces of China from 1990 to 2019, establishes an ARIMA model of urbanization rate and time, and predicts 2020 to 2050. Trend of urbanization rate in various regions. The data shows that, exclude individual areas, the urbanization rate of each area can reach 72% in 2030 and over 90% in 2050. However, the development of urbanization rates among regions is uneven, and relevant departments should formulate a reasonable development strategy on the basis of sustainable and balanced development
A method of designing high-voltage power using transformer parameters
Authors: Zhang Junling , Jin Renbo
Published: May 2021

PWM high-frequency high-voltage power has different ratio in light load and heavy load; often seriously affect the equipment’s indicators and reliability. In order to find out the cause of this phenomenon and avoid it well in the design, it is necessary to understand the distribution parameters of high-frequency high-voltage transformers and the effect of high-voltage rectifier circuits on circuit gain.
A Movable Test Device for Main Board Voltage
Authors: Liu Jinyu , Yang Teng , Li Dongze
Published: May 2021

Systematic thinking and mechanical physics methods are used to reform professional testing equipment and then to improve the working environment and conditions of professionals, which provides a design idea of movable test device for main board voltage. It is used to improve the efficiency of product quality test and maintenance. The device consists of two parts: the core component bearing system and the stability support system. The core component bearing system consists of a base, a test table, a voltage test device, a voltage test probe, and other components. The stability support system mainly provides functions such as component connection, core equipment fixing and equipment overall movement, including fixing columns, connecting rods, first baffles, first limiting plates, elastic parts, second baffles, lifting components, movable components and other components.
Ultrathin Muffler with Coherent Coupling Weak Resonance for HVDC Converter Station Medium Frequency Band Noise Control
Authors: Yang Dingge , Shang Yu , Han Yanhua , Li Wenhui , Wu Jingfeng , Niu Bo
Published: May 2021

HVDC converter station noise is mainly in medium frequency band, but the thickness of the conventional duct silencers are equivalent to the working wavelength, which makes them difficult to apply in narrow spaces. In this paper, through parallel and serial coupling of imperfect Helmholtz resonators with interpolated neck, a hybrid silencer with broadband perfect absorption is presented, which remain above 10 dB from 568 to 992 Hz with a thickness less than 20mm. In order to reveal the underlying physical properties and acoustic performance, simulations considering the coupling of acoustics and thermodynamics and impedance analysis are performed, showing a good consistency, and it’s further verified by experimental result. The results of research can help design effectively, ultra-thin and wide-band duct silencer for HVDC converter station medium frequency band noise control.
Research on Fault Current Endurance Capability of Concentric HTS Cable
Authors: Wu Xiaochen , Hu Ziheng , Zhang Bin , Wang Zhenzi , Wang Wei , Wang Zhe , Wang Bangzhu
Published: May 2021

Based on the resistance response of high temperature superconducting (HTS) YBCO tape under overcurrent, a physical model of compact three-phase concentric HTS cable under fault current was established using adiabatic approximation. We consider the endurance criteria of no irreversible damage to the superconducting tapes and no significant vaporization of LN2. The fault current endurance capability of concentric HTS cable was obtained at different fault currents. The safety of the superconducting cable can be ensured by adding current limiting device to reduce the fault current magnitude or by improving the relay system to reduce the protection action time.
Modelling and Optimization of Boiler Steam Temperature System Based on Neural Network and Genetic Algorithms
Authors: Zhang Kailiang , Li Fengping , Yi Chen , Huang Liang
Published: May 2021

The combination of neural network and genetic algorithm not only can improve the operating efficiency and economy of the boiler, but also give the recommended values of the operating parameters for the boiler operation. Based on the field data from power plant, the errors of the 3 and 4-layer neural network were compared according to the data experiments. The 4-layer neural network was used to model the steam temperature system. Taking the standard heat consumption as the target value, the adjustable and non-adjustable quantities of the input parameters of the steam temperature system are determined, and the genetic algorithm is used for optimization. The results show that the standard heat consumptions of all the 100 groups of working conditions are reduced. The maximum reduction of heat consumption is 186.88 kJ/(kW·h), and the average reduction is 153.93 kJ/(kW·h). This indicates that the combination of neural network and genetic algorithm can optimize the boiler steam temperature system by optimizing parameters such as superheater de-superheating water flow, superheater flue gas baffle opening and reheater flue gas baffle opening, which provides guidance for actual production.
Comparative study on the impact of clean energy on carbon emissions in different regions of China
Authors: Fan Xiangbo , Li Chenggang
Published: May 2021

Using the panel data of 30 provinces in China from 2008 to 2018, this paper compares the impact of clean energy on carbon emissions in different regions of China on the basis of extending the STIRPAT model. The results show that the impacts of clean energy on carbon emissions are different in different regions. The eastern region is not significant due to its developed economy and many influencing factors. The carbon emissions in the central and western regions are significantly affected by the energy structure, which reflects the relatively low scale of clean energy development in China and the huge dependence on fossil energy. In the future, one is to continue to strengthen the construction of clean energy; the other is to improve the technological level of the central and western regions and reduce their dependence on fossil energy.
Metallurgical Analysis of different processing technologies on tensile behavior of GH4169 superalloy
Authors: Chen Wen , Zhang Peng , Xie Jing , Liu Yang , Luo Ning
Published: May 2021

By the measurement of tensile property and microstructure observation, the different effect of 1MJ counter-blow hammer forging and 800MN die forging on the disc were investigated. In order to obtain final forging temperature, hot compression tests under 920~1030°C at 0.08 true strain were performed on GH4169 superalloy. The results showed that at the same processing parameter, ASTM 10 grain and granular δ were obtained by count-blow hammer forging, UTS is 1563Mpa; ASTM 8 grain and needle-like δ phase segregation were obtained by die forging, UTS is 1408Mpa. According to evolution of microstructure under isothermal compression, in one case that final forging temperature of count-blow hammer is about 1000°C, while it is 930°C under die forging. The microstructure of the forging is strongly related to the fabrication process, increase the preheating temperature of the die as much as possible, increase the pressing rate, excellent mechanical property can be obtained by die forging.
Influence of permeability on the minimum miscibility pressure between CO2 and crude oil
Authors: Liu Li , Guo Zhuang , Pi Yanfu , Liu Jinxin , Li Chengliang
Published: May 2021

The slim tube test is the industry standard for measuring the minimum miscibility pressure at present. However, there is a huge gap between the pore parameters of the slim tube model and the actual reservoir, especially the influence of permeability on MMP is not considered. The previous studies have shown that the minimum miscibility pressure is related to the pore structure and permeability of the reservoir. It is believed that there are some theoretical defects in the MMP measured by the slim tube test. This paper aims at the defect of slim tube test, core displacement experiment is carried out by using natural core to measure the minimum miscibility pressure under different permeability, and to reveal the law of the influence of permeability on the minimum miscibility pressure.
Numerical Simulation of Jet Forming Characteristics of Energetic Liner Based on Smoothed Particle Hydrodynamics Algorithm
Authors: Chen Baiquan , Shi Jiazheng , Ma Zihao
Published: May 2021

To study the jet forming characteristics of energetic material liner, in this paper, using AUTODYN simulation software and smoothed particle hydrodynamics (SPH) algorithm, the jet forming process of traditional metal Al liner and PTFE/Al energetic liner with different shapes, different cone angles and different thickness was simulated. The results show that the morphologies of PTFE/Al energetic jet and Al inert jet are significantly different, PTFE/Al jet has divergence compared with Al jet. With the increase of cone angle of liner, the velocity of jet tail increases, the velocity of jet head and the length of penetrator decrease. As the liner thickness increases, the head and tail velocity of the jet decrease, and the length of the penetrator increases.
Effects of post-annealing in different gas atmospheres on the properties of Tl-2212 films fabricated by sol-gel method
Authors: Jiang Yanling , Yue Hongwei , Wei Jinzhong , Chen Mingxian , Han Xu , Jin Yanying , Tang Pingying , Huang Guohua , Xie Qinglian
Published: May 2021

Tl-2212 superconducting thin films were fabricated on LaAlO3 (00l) substrates by sol-gel method. In the process, the precursor films were annealed in various gas atmospheres. XRD and EDX testing results showed that the precursors annealed in O2 converted into pure Tl-2212 superconducting phase, and the nominally stoichiometric cation ratio of TlBaCaCu was close to 2:2:1:2. The Tl-2212 film had a layered morphology and medium-quality superconductive parameters, which included the critical temperature T
c of 105.5 K, and the critical current density J
c of 0.8 MA/cm2 (self-field, 77K).
Gis-Based Fire Risk Spatial Assessment for Semiconductor Plant
Authors: Li Hongga , Huang Xiaoxia
Published: May 2021

Traditional fire risk assessment of semiconductor plant mainly relies on engineer experience from fields of fire control, chemistry, construction, semiconductor and insurance, and lacks a collaborative tool to integrate different design blueprints and locate high risk regions. In this paper, we introduce GIS into fire risk research for semiconductor industry, and propose a GIS-based spatial and quantitative method of fire risk assessment. Based on semiconductor plant spatial database extracted from diversified indoor maps, we set up a fire risk index system and integrate factors of potential fire source, operation risks of fabrication process, fire proof design and fire management to identify the high fire risk regions by using analytic hierarchy process. The proposed method improves spatial analysis capabilities of fire risk assessment for more and more complex semiconductor factories.
Application of an Improved Association Rule Algorithm in Rural Development Assessment in China
Authors: Zhang Chenguang , Teng Guifa
Published: May 2021

Association rules based on big data are derived from shopping basket analysis, which can deeply explore the association between things, and have been widely used in many fields. The traditional algorithm of association rules has several shortcomings, a new improved algorithm of association rules was proposed in this paper, which combines the precise advantages of Bayesian classifier with the full-scale characteristics of big data technology, and was applied to the rural development assessment process. After 2020, China’s rural industrial structure will undergo great changes, and environmental protection to drive economic development is an important part of it. The new association rules can be better adapted to the needs of the assessment. Through comparison, it can be seen that the confidence results obtained by the new association rules are more accurate than Pearson correlation coefficient. Finally, the association rules among CPI, per capita consumption expenditure and per capita disposable income are analysed, and suggestions for rural development have also been made.
Research progress on the application of phosphate oxygen isotope in environmental science - tracing sources and reaction mechanisms identification
Authors: Lin Xingjie , Zhang Chi , Miao Yu
Published: May 2021

Phosphorus is a vital element in the ecosystem, which plays an important role in ecosystem. Organic phosphorus compounds are widely distributed in soil and water bodies. As many organic phosphorus compounds are pollutants, they have potential threat to the environment. Therefore, the study of the cycling of organic phosphorus compounds in the environment plays an imperative role in the prevention and control of phosphorus pollution. As a geochemical tracer, the oxygen isotope in phosphate has been widely used in recent years to study the cycling process of phosphorus in nature. This article summarizes the application principle of phosphate oxygen isotope and its application in the tracing phosphorus sources and reaction mechanisms identification of organic phosphorus compounds. This work provides a reference for the future researchers.
Punching Shear in Reinforced Concrete Flat Slabs in Multi-Storey Car Park Building Structure
Authors: Chiang J C L , Tan W Z
Published: May 2021

Punching shear failure had been the cause of some fatal accidents that had occurred in the past in flat slabs of car park structure. A number of such failure reports had identified the underlying reasons being in the use of outdated or obsolete standards which have been phased out. Therefore, the design and analysis of punching shear strength in reinforced concrete flat slab is a key procedure that requires precision and accuracy. Over the years, although researchers had done a lot of experimental studies on the behaviour of flat slab structures, but the punching shear failures still happened despite many precautions being taken when designing for the car park structure. In this paper, some data that had been presented by previous researchers are used to identify the few design criteria for multi storey car park structure, and these results will also be compared with Eurocode 2 and two other standards, namely the phased out BS8110 and ACI318. From there the analysis for punching shear in multi storey car park structure is carried out using the Eurocode 2 approach considering the varying design parameters such as the sizes of column, slab thickness, span between columns and shapes of column. These parameters played a major role in assessing the punching shear strength in multi storey car park structure. In the model simulation, it was found that among the four selected parameters for study, the thickness of slab and the column size adopted are key factors that can enhance the punching shear strength capacity. On the other hand, the use of square column was proven to have an average of 27% higher punching shear strength than circular column. Besides that, the span between columns in two plane directions are best to range around 6m and 7m but due to car park functional expectations, a flat slab bay area of 8m × 6m and 9m × 6m can be recommended for the purposes of accommodating more car park spaces.
Potential of activated carbon in lime mortar plastering in term of fire resistance and thermal performance
Authors: Rahman M A A , Yazid A S , Awang M , Musa M K , Mustafa M S S , Hamidon N , Hashim N , Ahmad F
Published: May 2021

The use of lime mortar plastering for wall construction in residential and light commercial buildings has increased significantly over the world. The unique characteristic of hydrated lime increases the strength of the tensile bond. The more considerable the amount of cement content in cement lime mortar, the low the air content; thus, the bond strength stronger. The performance of plastering under fire exposure is an item of significant importance in securing construction. Activated carbon is one known adsorbent which has a high capacity to adsorb gases and improved fire resistance ability of concrete. The purpose of conducting this study is to identify the optimum proportion of lime mortar plastering containing activated carbon with different percentages which is 0%, 10%, 30% and 50% as cement replacement. Therefore, a fire resistance test was conducted on cement plaster mixtures with variable ratio content of activated carbon to identify the optimum proportion according to the temperature reading by an infrared thermometer for 30 minutes. Based on the results obtained, the sample with 30% activated carbon as cement substitution was the most effective since it gave a relatively low initial temperature reading which was 28.2°C. The test showed only a slight increase in temperature after the first five minutes, which is 93.1% and reached 108.2°C at maximum even after 30 minutes of testing. There was no hair crack developed, and no visible of smoke observed from the sample compared to existing plaster which formed hair crack and visible of smoke at 280°C after 16 minutes of testing. Therefore, 30% of activated carbon is the optimum proportion in lime mortar plastering due to ability to resist fire and prevention from hair crack and visible smoke formation. This proportion can be applied to the interior and exterior wall of the building, especially at the compartment wall and along the escape route.
Effect of Water-Cement Ratio on Mechanical Properties of Rubberized Fly Ash Concrete
Authors: Najmi A M , Mariyana A K , Shek P N , Nurizaty Z , Ramli M Z , Alel M N A , Mujedu K A , Aluko O G , Tohami M
Published: May 2021

One of the efforts to reduce the dependency of concrete production on natural resources along with carbon reduction is by utilizing recoverable materials as concrete constituents such as crumb rubber from scrap tires and fly ash from industrial waste. This study aims to investigate the mechanical properties of rubberized fly ash concrete which utilized crumb rubber and fly ash as a replacement for a proportion of fine aggregate and cement, respectively. Crumb rubber was used to replace 5 and 10% fine aggregate while fly ash was used to replace 10% OPC by weight. Three different water-binder (w/b) ratio, 0.55, 0.50 and 0.45, were used. The concrete specimens were prepared and tested for their density, compressive strength, splitting tensile strength, and flexural strength. Result gathered from the experimental works show a reduction in properties of rubberized concrete when compared to conventional concrete. By using a lower w/b ratio, the reduction tends to decrease and rubberized concrete with 0.45 w/b ratio recorded comparable density and strength to that normal concrete. The use of a lower water-binder ratio in concrete mix improved the strength of rubberized fly ash concrete equivalent to the normal concrete, allowing for usage of green materials in real building construction.
Structural Performance Assessment of High Strength Concrete Containing Spent Garnet under Three Point Bending Test
Authors: Budiea A. M. A. , Sek W. Z. , Mokhatar S. N. , Muthusamy K. , Yusoff A. R. M.
Published: May 2021

The utilization of river sand for miscellaneous construction purposes had directly increased due to rapid growth of construction industry. This fact caused over exploitation of riverbeds and troubled the eco-system. This study aims to find out the optimum percentage of spent garnet in high strength concrete and to forecast the structural performance of high strength concrete containing spent garnet with the previous research results. This study focusing on comparing and forecasting the utilization of 0%, 10%, 20%, 30% and 40% spent garnet as a sand replacement in high strength concrete at the age of 28 days. The level of 20% replacement of sand seen to be the optimum percentage of spent garnet for this concrete mixture to enhance its structure performance. It is concluded that, utilization of spent garnet in high strength concrete production able to reduce the dependency on river sand and lesser the waste from landfill.
Evalution on Strength Concrete Containing Micro Steel Fiber: A Review
Authors: Ramasamy S , Shahidan S , Rosdi A N H , Manaf A F A , Zuki S S M , Azmi M A M , Shamsuddin Shamrul-Mar , Abdullah S R , Ali N
Published: May 2021

Concrete has been used for a very long period in construction sites all over the globe. Concrete is very crucial in producing structural members in any building structure. It has to be strong enough to bear the loads of building so that it will not be failed. This article focused on a critical review of concrete containing micro steel fibres (MSF) in order to improve its ductility. In this study, the research is to determine whether the usage of micro steel fibre can improve the compressive and splitting tensile strength of concrete or not. In general, the strength of the concrete improves as the amount of MSF in the matrix increases. All the assessments conducted in all the paper that has been reviewed are following the standard test of British Standard. In a nutshell, the addition of micro steel fibre to concrete does have a huge impact on the tensile and compressive strength. The properties of concrete are expected to enhanced compared to normal concrete; however, the tensile strength does not show any improvement.
Performance of Sodium Silicate as Self-Healing Agent on Concrete Properties: A Review
Authors: Mokhtar Norfaniza , Hassan Muhammad Fitri Mah
Published: May 2021

Important materials in construction industry are concrete. Even though concrete is strong and durable, but it is still exposed to the crack. The most severe phenomenon of cracking happens in concrete without adequate and prompt care, and the framework of the crack continues to grow, which ultimately involves substantial potential maintenance costs increase. This study aims to review the effect of sodium silicate as self-healing agent on engineering properties and to observe the influence of sodium silicate inclusion in concrete on the microstructural characteristics. To obtain relevant paper for this research, a systematic literature review was used. The self-healing mechanism in a concrete help in reducing the cracking problem as it could delay the deterioration time and reduce the interaction of humans in managing the crack. Sodium silicate used in the concrete reacts with calcium hydroxide that already contains in the concrete to produce a new kind of binding material, namely calcium silicate hydrate (C-S-H). The outcome of this study has developed green and new technology to the concrete production in achieving sustainability which is the use of sodium silicate capable indicate healing properties in the cracking of concrete.
Effects of durian sawdust as a partial replacement of fine aggregate in concrete
Authors: Deraman Siti Noratikah Che , Rashid Muhammad Afif Daniel Abdul , Saad Siti Asmahani , Husain Nadiah Md. , Masjuki Siti Aliyyah
Published: May 2021

Recently, many researches all over the world are focusing on ways of utilizing either industrial or agricultural wastes as a source of raw materials for the construction industry. The aim of this study is to determine the optimum proportion of durian saw dust as partial replacement for fine aggregate. These wastes utilization would not only be economical but may also help to create a sustainable and pollution free environment. Durian sawdust is one such fibrous waste-product from durian skin. In this paper, untreated durian sawdust has been partially replaced in the ratio of 0%, 5%, 10% and 15% by volume of fine aggregate in concrete. Fresh concrete tests like compacting factor test and slump test were undertaken along with hardened concrete tests like compressive strength test and UPV test. The result shows that durian sawdust of 5% partially replacement of fine aggregate can be used for structural and non-structural purposes.
Finite element analysis on flexural behavior of nonprismatic longitudinal section reinforced concrete deep beam
Authors: Cahyati Martyana Dwi , Prayuda Hakas , Monika Fanny , Pratama Muhammad Mirza Abdillah , Siswantoro Eri Putra , Pradana Panji
Published: May 2021

Increasing of building constructions demand affects the innovation for developing structural elements, especially in the beam element known as deep beams. The deep beam is a popular beam with an adequate ratio of a/d < 1.0. Therefore, Compared to the standard beam, The strength of the deep beam shows better. It also can be applied to various construction. Based on observations in the field, the length of the cross-section of the deep beam varies significantly, starting from the prismatic and non-prismatic shapes. Therefore, this research has conducted to determine the effect of non prismatic longitudinal section variations on the RC deep beam behavior using finite element method. The simulation model analyzed consists of one prismatic longitudinal section and two types of the non-prismatic longitudinal section. The result shows that the non-prismatic longitudinal of the deep beam gives effects on slightly decreasing flexural load, ductility and failure mode. The failure modes shown in models show the same characteristics, which are both experiencing shear failure.
The Effectiveness of Microbubble Technology in The Quality Improvement of Raw Water Sample
Authors: Ali F , Azmi K N , Firdaus M R
Published: May 2021

An experimental study to observe the performance of microbubble generator (MBG) and microbubble-generating nozzle on water is carried out under laboratory conditions. The MBG is used to treat wastewater from water bodies which was impacted by domestic and industrial wastewater. The study uses MBG with a spherical body and a drilled hole, along with a dispersing nozzle placed at the bottom of microbubble reactor tank. The MBG used is considered to be more applicable for water bodies rather than other types. Two types of pressure gauges are installed around the MBG and the nozzle in order to examine and configure the inlet water pressure and the inlet gas pressure based on the best microbubble size produced from a prior experiment. Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Total Suspended Solids (TSS), and Turbidity has been analyzed in the beginning and every 10 minutes of a 60 minute detention time to examine the effectiveness of MBG. The results of study shows the MBG have a high rate of removal percentage in a 60-minute retention time with 60 to 90% for TSS, up to 90% for Turbidity, 74 to 96% for BOD, and 41 to 59% for COD.
Identification of Indoor Air Quality (IAQ) Sources in Libraries through Principal Component Analysis (PCA)
Authors: Mansor A Abu , Shamsul S , Abdullah S , Dom N C , Napi N N L Mohd , Ahmed A N , Ismail M
Published: May 2021

Indoor air quality (IAQ) is an important role in affecting visitors and staffs’ health in library. However, good ventilation and suitable types of furniture materials in the indoor environment were important to preserve better indoor air quality for the occupants. In this study, the status of indoor air pollution using in-situ measurement for chemical and physical parameters had been examined. The chemical parameters measured were formaldehyde (CH2O, ppm), carbon monoxide (CO, ppm), carbon dioxide (CO2), fine particulate matter (PM2.5, mg/m3) and coarse particulate matter (PM10, mg/m3). The physical parameters such as relative humidity (RH, %), temperature (T, °C) and air movement (AM, m/s) were also measured. The dominant sources of IAQ had been determined by using Principal Component Analysis (PCA). Principle Component (PC-2, S1) and PC-1 (S2) (CO, CO2 and CH2O) have become the indicator for chemical contaminants and the number of occupants that present in the library. The main contributor of indoor air quality at both areas was thermal comfort, which contributed 56.146% (PC-3, S1) and 60.76% (PC-4, S2). In conclusion, air quality in the libraries was affected by surrounding activities, ventilation performance and physical parameters.
Preparation of Synthetic Calcium Carbonate by Continuous Method
Authors: Mahim Z , Salleh E M , Othman R , Sabri S N Mohd
Published: May 2021

The production of precipitated calcium carbonate (PCC) was performed by a continuous method with additional mechanical stirring and retardant agent after the carbonation process. The PCC was produced at four different conditions i.e. without stirring and retardant agent (XSR), PCC with stirring only (S0), PCC with stirring, and 4g of a retardant agent (S4), and PCC with stirring and 20g of a retardant agent (S20). The continuous method 1 L of PCC slurry was consistently achieved at 7 minutes of the carbonation time that was controlled for all samples. The PCC yield was generally consistent with a slight reduction with increasing the retardant agent weight. Laser Particle Size Analyzer (LPSA) showed the finest PCC, which is 5.093 μm was produced without any additional mechanism (XSR) after the carbonation process. FESEM micrographs showed there were two types of PCC structure particles; fine hollow shape and coarse irregular shape. The result of Zeta potential portrayed the negative Zeta values for all samples with the highest values of -2.9 mV for S0 sample. The high purity of high-grade calcium carbonate for all samples was determined using X-ray Fluorescence (XRF). In general, there was no significant change occurred in the morphology of the PCC but offered a larger effect on particle refinement. Meanwhile, mechanical stirring resulted in an increment of the PCC particle size, but the retardant agent provided a particle refinement effect.
Assessment of Community Noise Annoyance due to Transverse Rumble Strips Installation at Residential Areas
Authors: Darus N , Haron Z , Yahya K , Mashros N , Othman M H , Wan Hassan W N F , Padil K H
Published: May 2021

Transverse rumble strips (TRS) acts as a traffic calming device to alert inattentive drivers, however, inappropriate design may generate excessive noise level which cause annoyance among the nearby residents. This study attempts to assess community noise annoyance by investigating current TRS designs and characteristics, measuring roadside noise level and traffic characteristics and evaluating noise annoyance due to TRS installation. Middle overlapped (MO), middle layer overlapped (MLO) and raised rumbler (RR) TRS profile types were selected. Noise indices such as A-weighted equivalent continuous sound pressure level (LAeq), sound level exceeding 10% (L10) and 90% (L90) of specified time were measured using sound level meter (SLM) based on ISO 11819 - 1: 2001 Acoustics: Measurement of the influence of road surfaces on traffic noise - Part 1: statistical pass-by (SPB) method. Traffic characteristics such as volume and speed were also measured. Then, community noise annoyance was evaluated in terms of LAeq changes, noise limit comparison by the Department of Environment (DOE) and traffic noise index (TNI) calculation. It was found that there are various TRS profile types with the thickness of only 3mm. Regardless the types, TRS installation has increased the roadside noise level of about 7dBA and exceeded permissible noise limits.
Properties of Bitumen Modified with Latex Under Short-Term Ageing
Authors: Jamaris U , Hassan N A , Mahmud M Z H , Ismail C R , Yaacob H , Hassan S A
Published: May 2021

Short-term ageing is a common issue in bitumen mixing production, and it severely affects the physical, rheological and chemical properties of the bitumen. Polymer modified bitumen is regarded as a preferable paving material to improve the performance of asphalt pavement against binder ageing. One of the additive types used to innovate modified bitumen is natural rubber (latex). This study evaluated the physical properties of bitumen modified with latex under ageing condition. Different percentages of latex (i.e. 2.5%, 5.0%, 7.5% and 10.0%) were added to the control 60/70 penetration grade (PEN) bitumen, which was then tested for penetration, softening point, viscosity, loss on heating and storage stability. The bitumen samples were conditioned under short-term ageing (i.e. rolling thin-film oven) prior to performance tests. Results indicated that modifying bitumen with latex hardens the conventional bitumen 60/70 PEN and potentially improves the bitumen’s resistance against temperature susceptibility with a high value of softening point. The addition of latex up to 10% produces a homogenous blend even after short-term ageing condition.
The Effectiveness of Home Delivery for Grocery based on External Cost
Authors: Edvian M R , Nahry  , Priadi C R
Published: May 2021

e-Grocery is one of the e-commerce sectors whose growth has increased significantly. This condition indicates the transition from conventional to online shopping and impacts the rate of home delivery services. Consequently, it may cause home delivery trips to produce the same or even greater externalities compared to conventional shopping trips. This study is aimed to analyze the effectiveness of home delivery based on the external cost aspect. Home delivery trips are analyzed using travel diary data of a grocery delivery service provider, whereas the conventional shopping trips are analyzed using the data taken from the consumers of conventional shopping. Compared to conventional shopping trips which are dominated by cars, home delivery using motorcycles produce an external cost of 23%-57% lower. In order to increase the effectiveness of home delivery, consumers are required to choose more than onetime window. This will provide a greater opportunity to do more efficient delivery routing.