bluuebunny/crossref_metadata_2025 huggingface dataset:
A REVIEW OF PERFORMANCE ASPHALT MIXTURES USING BIO-BINDER AS ALTERNATIVE BINDER
Authors: Mamat Rosmawati , Hainin Mohd Rosli , Abdul Hassan Norhidayah , Abdul Rahman Noor Azah , M. Warid M. Naqiuddin , Idham Mohd Khairul
Published: October 2019

This paper provides an overview of the performance in asphalt mixture using bio-binder from biomass as alternative binder. The bio-binder considered from the previous research was produced by pyrolysis process. The aim of this study is to review the performance of asphalt mixture modified by bio-binder.  The Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV) and Bending Beam Rheometer (BBR) were conducted to evaluate the rheological properties of bio-binder in asphalt mixtures. Many previous studies focused on the chemical composition, physical properties and performance of bio-binder in asphalt mixtures. Several research studies have evaluated the viability of bio-binder in asphalt pavement mixtures. Therefore, in many of these case the bio-binder was evaluated in minimal proportions (<10 percent). This is necessary in order to identify a mixtures containing bio-binder at higher blending proportions (up to 50% replacement). Additionally, a review will be a positive step in the direction of achieving mixture modified with bio-binder has shown similar or improved performance when compared to conventional mixtures.
APPLICATION DIRECT METHOD CALCULUS OF VARIATION FOR KLEIN-GORDON FIELD
Authors: Saiman Saiman , Agustino Rinto , Hamdani Hamdani
Published: October 2019

Klein-Gordon field is often used to study the dynamics of elementary particles. The Klein–Gordon equation was first considered as a quantum wave equation by Schrödinger in his search for an equation describing de Broglie waves. The equation was found in his notebooks from late 1925, and he appears to have prepared a manuscript applying it to the hydrogen atom. Yet, because it fails to take into account the electron's spin, the equation failed to predict the fine structure of the hydrogen atom, and overestimated the overall magnitude of the splitting pattern energy. This paper will describe in detail using the Direct Method of Calculus Variation as an alternative to solve the Klien-Gordon field equations. The Direct Method simplified the calculation because the variables are calculated and expressed in functional form of energy. The result of the calculation of Klien-Gordon Feld provided the existence of the minimizer, i.e.  with  and . Explicit form of the minimizer was calculated by the Ritz method through rows of convergent density
AIR POLLUTANT EMISSIONS IN BATAM: AN OVERVIEW
Authors: Triwinarko Andy , Kartikasari Dwi , Istardi Didi , Ghozali Syafei , Mulyaningtyas Dian
Published: October 2019

This paper aims at providing high quality air pollutant emissions analysis, so that policy makers have reliable information in shaping environmental priorities. The study was conducted in Batam, a special economic zone that is packed by industries.Emissions of NOx, CO, SOx, PM10,  and HC were estimated using the 2013 EMEP/EEA methods and those of COx were estimated using the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines, both were tier 2 methods where applicable. We found that powerplants, large-scale heavy industrymetals and mobile sources were important emission sources, while area sources such ashotels, hospitals, restaurants, universities, banks, malls, vehicle repairs, housings, gas stations, facilities under constructions, landfills, and electronics manufacturing companiescontributed much less significant to the total emissions. By mapping all sources, we found that the air pollution sources densely populated along the main streets. Conclusively, this paper recommends some measures to improve the overall air quality in Batam.
A REVIEW OF RECENT METHODOLOGIES, TECHNOLOGIES AND USABILITY IN ENGLISH LANGUAGE CONTENT DELIVERY
Authors: Cheng Lim Kok , Selamat Ali , Puteh Fatimah , Mohamed Farhan
Published: October 2019

English Language Teaching (ELT) and content delivery have undergone vast shift in this era of modernization. With analogue content digitized as a common form of knowledge delivery, methodologies equipped with current technologies have produced new perspectives on English Language Learning. This paper reviews the status, context, teaching parameters, assessment parameters, teaching strategies and usability in the current research capacity of ELT, highlighting the current works with technologies in their content delivery methods. Emerging technologies in ELT has also inspires the other spectrum of study involving the usability of technological interfaces, which has evolved constantly with the progression of human and computer interactivity. The aim of this research is to rediscover usability evolution surrounding the technologies in ELT and to redefine the gap existed in between English learning and tools interactivity. Current technologies and usability measures used in ELT will be discussed, highlighting the current trends in gauging interface interaction. A summary of comparative results in the aforementioned works will also be highlighted in this review paper, together with the categorization of reviewed parameters, variables and metrics in ELT. The reviews conducted have shown that there are still many unexplored areas in ELT, ELT technologies and usability in ELT.
MULTI OBJECTIVE MACHINING ESTIMATION MODEL USING ORTHOGONAL AND NEURAL NETWORK
Authors: Yusoff Yusliza , Mohd Zain Azlan , Sharif Safian , Sallehuddin Roselina
Published: October 2019

Much hard work has been done to model the machining operations using the neural network (NN). However, the selection of suitable neural network model in machining optimization area especially in multi objective area is unsupervised and resulted in pointless trials. Thus, a combination of Taguchi orthogonal and NN modeling approach is tested on two types of electrical discharge machining (EDM) operations; Cobalt Bonded Tungsten Carbide (WC-Co) and Inconel 718 to observe the efficiency of proposed approach on different numbers of objectives. WC-Co EDM considered two objective functions and Inconel 718 EDM considered four objective functions. It is found that one hidden layer 4-8-2 layer recurrent neural network (LRNN) is the best estimation model for WC-Co machining and one hidden layer 5-14-4 cascade feed forward back propagation (CFBP) is the best estimation model for Inconel 718 EDM. The results are compared with trial-error approach and it is proven that the proposed modeling approach is able to improve the machining performances and works efficiently on two-objective problems.
PARAMETER ESTIMATION FOR A MECHANISTIC MODEL OF HIGH DOSE IRRADIATION DAMAGE USING NELDER-MEAD SIMPLEX METHOD AND GENETIC ALGORITHM
Authors: Mohd Siam Fuaada , Ahmad Kamal Mohamad Hidayad , Johar Farhana
Published: October 2019

Radiation therapy is one of the cancer cells treatments that use high-energy radiation to shrink tumors and kill cancer cells. Radiation therapy kills cancer cells by damaging their DNA directly or creates charged particles within the cells that can in turn damage the DNA. As a side effect of the treatment, the radiation therapy can also damage the normal cell that located at parts of our body. The main goals of radiation therapy are to maximize the damaging of tumors cell and minimize the damage of normal tissue cell. Hence, in this study, we adopt an existing model of high dose irradiation damage. The purpose of this study is to estimate the six parameters of the model which are involved. Two optimization algorithms are used in order to estimate the parameters: Nelder-Mead (NM) simplex method and Genetic Algorithm (GA). Both methods have to achieve the objective function which is to minimize the sum of square error (SSE) between the experimental data and the simulation data. The performances of both algorithms are compared based on the computational time, number of iteration and value of sum of square error. The optimization process is carried out using MATLAB programming built-in functions. The parameters estimation results shown that Nelder-Mead simplex method is more superior compare to Genetic Algorithm for this problem.
THE UNSTEADY FREE CONVECTION FLOW OF ROTATING SECOND GRADE FLUID OVER AN OSCILLATING VERTICAL PLATE
Authors: Mohamad Ahmad Qushairi , Khan Ilyas , Ismail Zulkhibri , Shafie Sharidan
Published: October 2019

In this paper, the exact solutions for unsteady free convection flow of rotating second grade fluid over an isothermal oscillating vertical plate are investigated. This phenomenon is modeled in the form of partial differential equations with initial and boundary conditions. Some suitable non dimensional variables are introduced. The corresponding non-dimensional equations with conditions are solved using Laplace transform technique. Exact solutions for velocity and energy profiles are obtained. They are expressed in simple forms in terms of exponential and complementary error functions of Gauss. It is found that they satisfy governing equations and conditions imposed. Computations are carried out and the results are analyzed for various emerging parameters.
ADSORPTIVE REMOVAL OF METHYLENE BLUE AND ACID ORANGE 7 BY HEXADECYLTRIMETHYLAMMONIUM BROMIDE MODIFIED RICE HUSK
Authors: Kamaru Auni Afiqah , Ahmad Jani Nurul Soraya , Nik Malek Nik Ahmad Nizam , Sani Nor Suriani
Published: October 2019

The feasibility of rice husk (RRH) and surfactant modified rice husk (SMRH) to adsorb cationic dye, methylene blue (MB) and acid orange 7 (AO7) from aqueous solution was studied. SMRH was prepared by reacting RRH with different initial concentrations (1.0, 2.5 and 4.0 mM) of cationic surfactant quaternary ammonium compound, hexadecyltrimethylammonium bromide (HDTMABr). RRH and SMRH were characterized using Fourier transform infrared (FTIR) spectroscopy to determine surface functional group and effect of surfactant modification on the structure of RRH. Adsorption studies were performed in a series of batch experiment and effect of initial dye and HDTMABr concentrations on the adsorption capacity of RRH and SMRH were evaluated. The results showed that the removal of MB was higher for RRH compared to SMRH meanwhile AO7 removal was higher for SMRH compared to RRH. Modification of rice husk by cationic surfactant was proven to decrease the adsorption site for MB. On the other hand, the presence of surfactant on SMRH increased the adsorption site and allows more adsorption to occur for AO7. The equilibrium data were better described by Langmuir isotherm with maximum adsorption capacity for MB was 100.0 mg/g and 200.0 mg/g for AO7. In conclusion, the modification of rice husk by HDTMABr decreased the adsorption towards cationic dye but increased the adsorption towards anionic dye
EXPERIMENTAL INVESTIGATION OF FLOW RATE’S EFFECT ON SURFACTANT-ALTERNATING-GAS FOAM PROCESS
Authors: Hematpur Hamed , Mahmood Syed Mohammad , Mohamad Amer Mongy
Published: October 2019

The gas injection is one of the most common methods to increase oil recovery. However, there are several drawbacks in the application of this method due to density and viscosity differences between displaced and displacing fluids. In order to tackle these drawbacks, gas can be utilized as different forms of foam which one of these methods is called Surfactant-Alternating-Gas (SAG). Although many studies have been conducted on foam flow through porous media, the behavior of foam still is moot to some extent. Since, the elaboration of SAG foam behavior in porous media is the aim of this study. However many parameters affect SAG foam behavior, the injection flow rate plays a significant role in foam behavior. In this study, we investigated the flow rate’s effect on SAG behavior. To achieve this target, several cores flooding, in the absence of oil, were conducted and results were interpreted. The experimental design for this work included core flooding apparatus, IOS as surfactant and nitrogen as injected gas. The experiments were interpreted in term of liquid recovery and pressure drop. The results show that the SAG efficiency highly depends on gas flow rate which high injection flow rate, low SAG foam efficiency.
THE PHOTOCHEMISTRY OF CR(CO)6 IN HIGH PRESSURE LOW TEMPERATURE POLYMER MATRIX MONITORED BY FOURIER TRANSFORM INFRARED AND UV-VIS SPECTROSCOPY
Authors: W. Harun Farah
Published: October 2019

The aim of this work is to develop a new type of polymer matrix which can be used to study the reactive intermediates produced from UV photolysis of metal carbonyl complexes measured with FTIR as well as UV-vis spectroscopy. The photochemistry of Cr(CO)6 impregnated in Teflon-AF polymer with the presence of N2, CH4 and even weak ligand i.e.Xe and He were conducted at extremely low temperature.  Photolysis of Cr(CO)6 under N2 environment produces up to four carbonyl groups being replaced with the N2. Meanwhile, the photochemistry of Cr(CO)6 under Xe and CH4 produce the reactive complexes of Cr(CO)5(Xe) and Cr(CO)5(CH4)respectively. Teflon-AF was found to be the suitable matrix material as the –C–F– bond binds very weakly to the metal center.
CFD MODELING OF BINARY MIXTURE HYDRODYNAMICS IN GAS-SOLID PARTICLE FLUIDIZED BED REACTOR SYSTEM
Authors: Tangpattanatana Thanatepon , Jiradilok Veeraya , Piumsomboon Pornpote , Chalermsinsuwan Benjapon
Published: October 2019

The objective of this research was to compare the effect of a binary mixture between coal, including 500, 700 and 1000-micron size, and sand, 180-micron size, on the mixing behavior in a fluidized bed system. In addition, suitable computational fluid dynamics drag models were explored, including an EMMS model, Gidaspow model and Wen & Yu model. The simulation results were compared for correctness with real plant information. The EMMS model matched well with the obtained data, This is because the employed model considers the particle cluster effect. The EMMS drag model was then used for further computational fluid dynamics simulation. The levels of mixing between sand and coal were predicted by turbulent dispersion coefficient. These coefficients of coal particle were exhibited in axial and radial direction. The highest turbulent dispersion coefficients were found in the mixture with 500 and 1000 micron coal size for radial and axial directions, respectively. The low axial turbulent dispersion coefficient and high radial turbulent dispersion coefficient were preferred for good hydrodynamics behavior.
PURIFICATION AND CHARACTERISATION OF FIBRINOLYTIC ENZYMES FROM ENDOPHYTIC FUNGI AND LIGNOSUS RHINOCERUS
Authors: Mohd Noor Zainon , Ahmad Mohd Sidek , Zainal Ariffin Zaidah
Published: October 2019

Three enzymes FH3, S13 and LR1 from three different sources showed fibrinolytic activities. Two were from endophytic fungal cultures and one from the sclerotium of Lignosus rhinocerus mushroom (LR1). FH3, S13 cultures and LR1, the crude extract of the sclerotium were concentrated and purified by ammonium sulphate precipitation, ion-exchange chromatography and gel-filtration. The molecular weights of the FH3, S13 and LR1 purified enzymes were estimated to be approximately 34kDa, 34kDa and 10kDa, respectively. Maximum fibrinolytic activities were observed for FH3 at pH 7 and 30°C, S13 at pH 8 and 40°C and LR1 at pH 6 and 40°C.  In our earlier paper we identified FH3 as Fusarium sp. and S13 as Penicilium citrinum.
A THEORETICAL MODEL FOR PORTFOLIO OPTIMIZATION DURING CRISIS
Authors: Cheong Kiat Gan Colin , Kaderi Wiryono Sudarso , Koesrindartoto Deddy Priatmodjo , Arta Surya Budhi
Published: October 2019

The premise of this paper is providing a theoretical model for a novel way to portfolio optimization using generalized hyperbolic distribution during crisis with risk measures, expected shortfall and standard deviation. Getting good expected returns from investing in portfolio assets like stocks, bonds and currencies during crisis period chosen is harder where the risks cannot be diverted because of disruptive financial jolts i.e. sudden and unprecedented events like subprime mortgage crises in 2008. Multivariate generalized hyperbolic distribution on joint distribution of risk factors from stocks, bonds and currencies is used because it can simplify the risk factors calculation by allowing them to be linearized. The results show the premise is true. The contributions are discovering both the appropriate probability distribution and risk measure will determine whether the portfolio is optimal or not. The practical application will be taking care of the risk to take care of the profit.
AN ALGEBRAIC PROBLEM ARISING IN BIOMATHEMATICS
Authors: Sylviani Sisilia , Carnia Ema , Supriatna A. K.
Published: October 2019

This paper discusses a matrix model that describes the dynamics of a population with m live stages and lives in n patch seen from algebra viewpoint. The matrix D describes population growth in a patch or location. The matrix D is defined as a matrix obtained from matrix multiplication of a permutation matrix with a block diagonal matrix that its diagonal blocks is matrices with non-negative entries and transpose of a permutation matrix [4]. It will be shown that the permutation matrix contained in D has a special form.
OPTIMIZATION OF CURCUMA LONGA L. RHIZOME SUPERCRITICAL CARBON DIOXIDE EXTRACTION (SC-CO2) BY RESPONSE SURFACE METHODOLOGY (RSM)
Authors: Mohd Shah Siti Hafsah , Abdul Haiyee Zaibunnisa , Ismail Khudzir , Hashim Nooraain , Wan Ismail Wan Iryani
Published: October 2019

Fast, selective and reliable extraction technique namely Supercritical Carbon Dioxide Extraction (SC-CO2) has been proposed in this study. Experiments were carried out to determine the optimum conditions for pressure and temperature of SC-CO2 extraction for Curcuma longa L. using response surface methodology (RSM) based on central composite design (CCD) with the aim to obtain the highest percentage of yield and curcuminoid concentration. At a pressure of 4807 psi and temperature of 90°C, extraction of turmeric rhizome using SC-CO2 extraction resulted in oil yield of 7.54% (dry weight basis) and curcuminoid concentration of 0.023 mg 100-1g of dry turmeric rhizome. From the study, it can be concluded that the percentage yield and curcuminoid concentration was significantly influenced by pressure and temperature.
BODY IMAGE PERCEPTION, BODY SHAPE CONCERN AND BODY SHAPE DISSATISFACTION AMONG UNDERGRADUATES STUDENTS
Authors: K. Kamaria, , M. Vikram, , R. Ayiesah,
Published: October 2019

There are significant surge on body image concern among young adults globally. The negative body image eventually leads to body shape dissatisfaction (BSD) and consequently would cause unfavorable outcomes such as anxiety, depression, low-self-esteem and poor quality of life. The self-reported body mass index (BMI), Self-rating Body Silhouette and Body Shape Questionnaire (BSQ-16A) were used to identify relationship of body image perception, body shape concern with body shape dissatisfaction (BSD) among undergraduates’ students at Health Science Faculty UiTM, Malaysia.  Majority  of males and females  were in normal category  on body image perception with 64.7  % and 61 % respectively. About 79.4 % of male and 82.7 % female perceived their body weight as ideal body weight. On body shape concern, 67.6 % of male and 45.7 % of female were not concerned of their shape. Approximately 48.1 % of females were dissatisfied with their body shape and desire to become thinner contrary 44.1 % of male desire to become heavier. In addition increase in body shape concern lead decrease BSD. In view of their ignorance to achieve the desired body image and body shape concern may raise fear of unhealthy eating practices especially among female’s students. Thus, health awareness programs, health promotion, and health screening are to be necessitated among female university students to alleviate the potential risk of unhealthy eating behaviors.
CHEMICAL CONSTITUENTS AND IN-VITRO ANTIMICROBIAL ACTIVITY OF POLYALTHIA STENOPETALA ESSENTIAL OIL
Authors: Kamaruddin Noor Izzatie Munira , Mohamad Ali Nor Azah , Safian Muhd Fauzi , Zainal Ariffin Zaidah
Published: October 2019

Polyalthia stenopetala essential oils were extracted by hydrodistillation from the leaves and were analyzed using gas chromatography-flame ionization detector (GC-FID) and gas chromatography/mass spectrometry (GC/MS) system. Thirty one compounds were identified from the analysis. The most abundant components in the leaves oil are curzerene (37.56%) followed by viridiflorol (11.59%), germacrene B (3.77%) and aromadendrene (4.01%). The antimicrobial activity of the oil essential oils was determined with disk diffusion method and minimum inhibitory concentration (MIC) assay. Four bacteria, Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 25922) Psedomonas aeruginosa (ATCC 10145) and two yeasts, Candida albicans (ATCC 10231) and Saccharomyces cerevisiae (ATCC 4098) were selected. The crude oil shows the most reactivity against B. subtilis (ATCC 6633) and C. albicans (ATCC 10231) with an inhibitory zone of 11mm. The minimum inhibitory concentration (MIC) of sample against Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 25922) Psedomonas aeruginosa (ATCC 10145) and Candida albicans (ATCC 10231) in range of 0.5 mg/ml – 1.0 mg/ml which can categorized as strong.
NEW ANTIRHEUMATIC SUBSTANCE BASED ON PHENOLIC GLYCOSIDE STRUCTURE METHYL (4-О-Β-GLUCOPYRANOSYLOXY)-BENZOIC ACID
Authors: Alexey Nemtsev , Ivan Smirnov , Tatyana Murashko , Alexey Ivanov , Alex Bondarev , Vladimir Udut
Published: October 2019

Rheumatoid arthritis (RA) is a chronic inflammatory multifactorial disorder affecting approximately 1% of population, with over 3000000 new cases annually. The principal pharmacological agents are nonsteroidal anti-inflammatory drugs (NSAID). Patients with rheumatoid arthritis are vulnerable to NSAID-associated gastrointestinal complications. Based on these findings we developed a new NSAID agent based on phenolic glycoside structure methyl (4-О-β-glucopyranosyloxy)-benzoic acid. In this study we evaluated the methyl (4-О-β-glucopyranosyloxy)-benzoic acid therapeutic effect in adjuvant-induced rat arthritis compared to etoricoxib effect. According to the results, methyl (4-О-β-glucopyranosyloxy)-benzoic acid activity was superior to etoricoxib, paw volume returned to the initial value 2 days early, than it did in etoricoxib group. Therefore, methyl (4-О-β-glucopyranosyloxy)-benzoic acid might contest to the modern antirheumatic drug etoricoxib.
PROTEOLYTIC FUNGI FROM VIRGIN FOREST
Authors: Zainal Ariffin Zaidah , Ahmad Mohd Sidek , Pepi Rosalia , Mohd Noor Zainon
Published: October 2019

Microbial enzymes have continued to assist diverse reactions as biocatalysts. Soil derived microbes offer a prospective resource for such enzymes. Screening and isolation of proteolytic fungi were carried out from soil sample of a Malaysian virgin forest. Four isolates showed clear zone of protein hydrolysis on skim milk agar representing proteolytic activity. Aspergillus flavus UOA/HCPF 5774 exhibited the highest proteolytic activity with a clear zone diameter of 21 mm followed by Aspergillus niger and Trichoderma harzianum both with a clear zone of 16 mm, and Penicillium simplicissimum strain LP42 with a13 mm clear zone. Crude protease activity of 0.230 – 0.277 Units / ml for each fungus was seen after 24 hours incubation. A decline of protease production was observed after 48 hours incubation except for Aspergillus flavus UOA/HCPF 5774 which showed a drop only after 72 hours incubation. The protease producing fungi were partially identified based on their morphological characteristics, macroscopic and microscopic identification. The identification was confirmed by 18S rRNA Sequence Analysis. The four fungi protease producers were Aspergillus niger, Penicillium simplicissimum strain LP42, Aspergillus flavus UOA/HCPF 5774 and Trichoderma harzianum.
EFFECT OF BALL MILLING OF FLY ASH PARTICLE SIZE ON FOAM STABILIZATION FOR EOR APPLICATIONS
Authors: Ahmad Ishaq , Awang Mariyamni , Sufian Suriati , Khan M Irfan , Mumtaz Mudassar
Published: October 2019

In enhanced oil recovery (EOR), nanoparticles have gained the potential to improve foam stability. In this study, the potential of fly ash to produce stable foam by using shaker was studied. Fly ash nanoparticles were developed by the mechanical treatment using ball mill. Sample to ball ratio of 1 to 10 was applied to investigate the effect of ball milling on particle size distribution of fly ash. The mechanically activated fly ash was mixed at various concentrations (ppm) with the anionic foaming surfactants AOS14-16. Foam stability tests were performed at ambient conditions by making solution through shaker. Stable foams were generated using varies types of fly ash particles. It was observed that the small sized fly ash has more potential towards foam forming ability and foam stability. Therefore, the mechanically activated fly ash resulted in a considerably increased EOR.
TENSILE PROPERTIES OF UNIDIRECTIONAL KENAF FIBER POLYPROPYLENE COMPOSITE
Authors: Tholibon Dulina , Sulong Abu Bakar , Muhammad Norhamidi , Ismail Nur Farhani , Tharazi Izdihar , Md Radzi Mohd Khairul Fadzly
Published: October 2019

Over the last decade, awareness of environmental issues and the shortage of petroleum resources contribute to the important factors that encourage researchers to explore the potential use of natural fibers such as kenaf as reinforcement in ﬁber reinforced composites. The objective of this study was to investigate the effect of different processing condition (temperature, pressure and pressing time) on the tensile properties of unidirectional kenaf fiber polypropylene composite. Samples of composites were prepared by a hot pressing method. In this work, kenaf continuous long fibers from water retting process at 40%wt were aligned in parallel. Polypropylene (PP) in the form of pellets and powder had been used as a matrix. The results showed that, samples produced at temperature 2100C and pressure 5 MPa for 6 minutes hot pressing gives excellent tensile properties which 262% of improvement as compared to pure PP. This indicates that, kenaf fiber is suitable as reinforcement in polymer composite.
LOAD CAPACITY COEFFICIENT EVALUATION OF THREE-LAYERED JOURNAL BEARING WITH SLIP
Authors: Rao T. V. V. L. N. , Rani A. M. A. , Awang M. , Hashim F. M.
Published: October 2019

Analysis of three-layered journal bearing with slip on bearing surface is presented. A modified classical Reynolds equation is derived for slip on bearing surface taking into consideration of bearing surface, core and journal surface layers. The modified Reynolds equation is derived taking into consideration of lubricant layer’s film thickness, viscosities and slip on the bearing surface. Navier slip boundary conditions are used to analyze slip. Results of load capacity coefficient are presented for three-layered and two-layered journal bearing with slip. The load capacity coefficient decreases with bearing surface with slip. For a three-layered journal bearing with slip, high viscosity bearing surface layer results in higher load capacity coefficient.
ABERRANT DRIVING AMONG YOUNG MALAYSIAN DRIVERS
Authors: Ismail Rozmi , Voon Ng Lei , Md Saad Mohamad Hanif , Saleem Muhammad , Ibrahim Norhayati
Published: October 2019

This paper discusses the result of a quasi experimental study aimed to investigate the relationship between personality traits and aggressive (aberrant) driving among young Malaysian drivers. 127 students with mean age of 22 (68 males and 59 females) and valid class B2 driving license were recruited for the study. Before exposure to experimental intervention, the participants completed Eysenck's Impulsivity Inventory (aka IVE Questionnaire) which assessed personality traits (impulsiveness, venturesome and empathy), and AVIS Questionnaire, developed by Vienna Test System (VTS) which assessed aggressiveness while driving. In the experiment the participants were shown video scenarios of aggressive driving as a stimulus for aggressive driving evaluation. They were then asked to respond to questions related to provocations and aggressive behaviour from other drivers on to themselves and of other drivers being provoked by the same situation. The results revealed significant relationship between empathy and personality types (p<0.05) where subjects who score low on empathy and high on venturesome-ness tended to be more aggressive. Even though nearly all participants admitted that Malaysian drivers were aggressive on the road, only 15% of the participants agreed that they are aggressive drivers themselves. Based on this study's results, it is suggested that personality screening tests should be implemented by the relevant agencies as a preliminary measure to reduce the road rage phenomena and aggressive driving.
JOHNSON COOK CONSTITUTIVE MODELING FOR AUSTENITE METAL IN HOT FORMING PROCESS
Authors: Senin Azman , Mohd Nopiah Zulkifli , Mohd. Ihsan Ahmad Kamal Ariffin , Abdullah Shahrum , Abd Wahab Dzuraidah , Jamaludin Muhammad Jamhuri , Zakaria Ahmad
Published: October 2019

Numerical computations have helped process engineers in designing the stamping process with minimal process defects. The constitutive modelling for hot stamping represents a complex relationship between stress, strain, strain rate and process temperature. The sheet thickness is 1.5 mm were prepared according to the ASTM standard. The flow curve properties of NPH-1500 sheet were investigated by conducting uniaxial tension tests with temperature from 600oC to 800oC and subjected to strain rate of 0.1/s,1/s and 10/s. The flow curves for the respective experiment runs were investigated and modelled with Johnson Cook constitutive modelling where the important metal parameters were derived. Based on the results, the error of the metal parameters values from experimental works and commercial database was found to be less than 5%.
GAMING EXPERIENCE ON THE MOBITOP SYSTEM: A COLLOCATED AD-HOC COLLABORATION SYSTEM
Authors: Rhun Ming Teo , Beng Liang Ong , Mohd Norowi Noris , Mansor Evi Indriasari , Dey Prasenjit , Jamil Izdihar
Published: October 2019

This paper presents the study on the mobiTop system- a collocated multi-mobile system. The mobiTop system allows users to come together with their mobile devices in an ad-hoc manner to create one seamless and extended interactive display surface. The collocated multi-mobile system allows a group of people to play digital games together in an impromptu manner without having to buy an interactive tabletop equipment. This study investigates the user experience and system design of a collocated multi-mobile system when users play a collaborative game-based application using the mobiTop system. The findings show that the extended screen size of the mobiTop system enhanced the collaborative experience of the users. This study also highlights several design considerations to further improve such systems such as employing a faster network configuration, reducing the bezel effect, catering for dynamic device movements and making the object of interest more prominent and visible. With this understanding, this study present design guidelines to help designers create digital game-based multi-mobile systems for ad-hoc collaboration.
Numerical Investigations of Pollutant Emissions From Novel Heavy-Duty Gas Turbine Burners Operated With Natural Gas
Authors: Pampaloni Daniele , Nassini Pier Carlo , Andreini Antonio , Facchini Bruno , Cerutti Matteo
Published: October 2019

A numerical investigation of pollutant emissions of a novel dry low-emissions burner for heavy-duty gas turbine applications is presented. The objective of this work is to develop and assess a robust and cost-efficient numerical setup for the prediction of NOx and CO emissions in industrial gas turbines and to investigate the pollutant formation mechanisms, thus supporting the design process of a novel low-emission burner. To this end, a comparison against experimental data, from a recent experimental campaign performed by BHGE in cooperation with University of Florence, has been exploited. In the first part of this work, a Reynolds-averaged Navier–Stokes (RANS) approach on both a simplified geometry and the complete domain is adopted to characterize the global flame behavior and validate the numerical setup. Then, unsteady simulations exploiting the scale adaptive simulation (SAS) approach have been performed to assess the prediction improvements that can be obtained with the unsteady modeling of the flame. For all simulations, the flamelet generated manifold (FGM) model has been used, allowing the reliable and cost-efficient application of detailed chemistry mechanisms in computational fluid dynamics (CFD) simulation. However, FGM typically faces issues predicting flame emissions, such as NOx and CO, due to the wide range of time scales involved, from turbulent mixing to pollutant species oxidation. Specific models are typically used to predict NOx emissions, starting from the converged flow-field and introducing additional transport equations. Also CO prediction, especially at part-load operating conditions could be an issue for flamelet-based model: in fact, as the load decreases and the extinction limit approaches, a superequilibrium CO concentration, which cannot be accurately predicted by FGM, appears in the exhaust gases. To overcome this issue, a specific CO-burn-out model, following the original idea proposed by Klarmann, has been implemented in ANSYS fluent. The model allows to decouple the effective CO oxidation term from the one computed by FGM, defining a postflame zone where the source term of CO is treated following the Arrhenius formulation. In order to support the design process, an indepth CFD investigation has been carried out, evaluating the impact of an alternative burner geometrical configuration on stability and emissions and providing detailed information about the main regions and mechanisms of pollutants production. The outcomes support the analysis of experimental results, allowing an indepth investigation of the complex flow-field and the flame-related quantities, which have not been measured during the tests.
Simple Contact Stiffness Model Validation for Tie Bolt Rotor Design With Butt Joints and Pilot Fits
Authors: Rimpel Aaron M. , Leopard Matthew
Published: October 2019

Tie bolt rotors for centrifugal compressors comprise multiple shaft components that are held together by a single tie bolt. The axial connections of these rotors—including butt joints, Hirth couplings, and Curvic couplings—exhibit a contact stiffness effect, which tends to lower the shaft bending frequencies compared to geometrically identical monolithic shafts. If not accounted for in the design stage, shaft bending critical speed margins can be compromised after a rotor is built. A previous paper had investigated the effect of tie bolt force on the bending stiffness of stacked rotor assemblies with butt joint interfaces, both with and without pilot fits. This previous work derived an empirical contact stiffness model and developed a practical finite element modeling approach for simulating the axial contact surfaces, which was validated by predicting natural frequencies for several test rotor configurations. The present work built on these previous results by implementing the same contact stiffness modeling approach on a real tie bolt rotor system designed for a high pressure centrifugal compressor application. Each joint location included two axial contact faces, with contact pressures up to five times higher than previously modeled, and a locating pilot fit. The free-free natural frequencies for different amounts of tie bolt preload force were measured, and the frequencies exhibited the expected stiffening behavior with increasing preload. However, a discontinuity in the data trend indicated a step-change increase in the contact stiffness. It was shown that this was likely due to one or more of the contact faces becoming fully engaged only after sufficient tie bolt force was applied. Finally, a design calculation was presented that can be used to estimate whether contact stiffness effects may be ignored, which could simplify rotor analyses if adequate contact pressure is used.
Double replication for characterizing cracks in surface-hardened polydimethylsiloxane
Authors: Leifels Miriam , Mayer Andre , Scheer Hella-Christin
Published: October 2019

Surface-hardened polydimethylsiloxane (PDMS) with random cracks is studied by means of double replication. The PDMS samples are prepared under different curing conditions, resulting in a different Young's modulus of the bulk. To modify the surface, an excimer lamp at 172 nm is used. The samples are stretched uniaxially until the first cracks appear. As an evaluation under strain is hard or rather impossible, the idea is to replicate the cracked sample in a curable material and to characterize the cracks by inspection of the replica. To protect the sample from mechanical loading, this replication is done by molding in OrmoStamp on glass; these replicas are used for optical inspection to determine the crack spacing. As a characterization of the depth and width of the cracks is highly facilitated when cleaving is enabled, a second replication is performed into a thin layer of SU-8 on Si; these second replica are analyzed by secondary electron microscopy of cross sections. They provide a realistic picture of the crack shape. It is found that the curing conditions affect the crack shape; a U-shape occurs with a low bulk modulus, whereas a V-shape occurs with a high bulk modulus. The parameters width, depth, and spacing are largely unaffected by the curing conditions. This work provides a background to understand the behavior of random cracks, which is, e.g., useful to design a system with controlled cracks that remain stable. An important finding is that as soon as cracking occurs at a certain strain, already a number of cracks develop, yet without any further stretching. The cracks behave independently from neighboring cracks. Upon further stretching, new cracks develop, and the crack width and depth remain similar. Therefore, these random cracks are stable, and sample failure does not occur up to a strain of at least 40%.
Longitudinal Trajectories of Children’s Physical Activity and Sedentary Behaviors on Weekdays and Weekends
Authors: Zhang Peng , Lee Jung Eun , Stodden David F. , Gao Zan
Published: October 2019

Background: The objective was to examine changes of children’s time spent in sedentary, light physical activity, moderate to vigorous physical activity (MVPA), and estimated energy expenditure (EE) rates during weekdays and weekends across 3 years.Methods: An initial sample of 261 children’s (mean age = 7.81 y) 5-day physical activity and EE were assessed annually via accelerometry across 3 years using repeated-measures multivariate analysis of variance. The outcome variables were time spent in sedentary, light physical activity, MVPA, and kilocalories per day for weekdays and weekends.Results: A significant decrease in MVPA and EE occurred during weekdays across the 3 years (P = .01). Only the second-year data demonstrated an increase (+2.49 min) in weekend MVPA (P = .04). Children’s sedentary time during weekdays increased significantly in years 1 and 2 (P = .01), yet significantly decreased in the third year (−44.31 min). Children’s sedentary time during weekends significantly decreased in the first year (−27.31 min), but increased in the following 2 years (P = .01). Children’s light physical activity demonstrated a statistically significant increase in year 2 (+3.75 min) during weekdays (P = .05).Conclusions: Children’s MVPA and EE generally declined during weekdays but were maintained during weekends across a 3-year time span. Children may benefit most from weekday intervention strategies.
Ultrasonographic and Myotonometric Evaluation of the Shoulder Girdle After an Isokinetic Muscle Fatigue Protocol
Authors: Klich Sebastian , Pietraszewski Bogdan , Zago Matteo , Galli Manuela , Lovecchio Nicola , Kawczyński Adam
Published: October 2019

Objectives: The aim of the study was to investigate supraspinatus tendon thickness, acromiohumeral distance (AHD), and stiffness/creep measures of the shoulder girdle in overhead asymptomatic athletes in muscle fatigue conditions. Design: Observational, case series study. Setting: Biomechanics and motion analysis lab. Participants: Twenty-four male overhead volleyball (n = 8), handball (n = 8), and tennis (n = 8) athletes. All subjects were without shoulder injury history. Main Outcome Measure: The subjects were tested for supraspinatus tendon thickness (in short and long axis), AHD using ultrasound scans and stiffness/creep of upper trapezius, infraspinatus, anterior and posterior deltoid, and pectoralis major using the myotonometer device before and immediately after a fatigue protocol. Intervention: The fatigue protocol consisted of 3 sets of 32 maximum isokinetic concentric contractions performing shoulder internal and external rotation at isokinetic speed of 120°/s. Results: A significant increase in supraspinatus tendon thickness (both in short and long axis) (P = .045 and P = .01, respectively) and a reduction in AHD (P = .01) were found after an isokinetic protocol. The stiffness increased significantly in upper trapezius (P ≤ .01), infraspinatus (P = .003), posterior deltoid (P = .047), and pectoralis major (P = .01), whereas the creep showed a significant decrement for upper trapezius (P = .001) and infraspinatus (P = .003). Conclusion: The present study has demonstrated the postexercise fatigue in overhead athletes. The increase of stiffness (reduction of muscle creep) and tendon thickness (simultaneous to the reduction of AHD) may indicate rotator cuff overloading as a primary intrinsic tendon pathology process.
The Importance of Functional Hamstring/Quadriceps Ratios in Knee Osteoarthritis
Authors: Aslan Özlem , Batur Elif Balevi , Meray Jale
Published: October 2019

Context:Osteoarthritis (OA) is the most common chronic joint condition. Muscle dysfunction plays a critical role in the pathogenesis of knee OA.Objective:It has been suggested that the agonist–antagonist strength relationship for the knee may be better described by a functional hamstring/quadriceps (H/Q) ratio (Hconcentric/Qeccentric: the representative of knee flexion and Qeccentric/Hconcentric: the representative of knee extension). Therefore, in this study, the authors aimed to investigate this ratio and its importance for knee OA.Design:Cross-sectional study.Setting:Research clinic.Patients or Other Participant(s):Twenty healthy women and 20 women with grade 2 or grade 3 primer knee OA between the age of 50 and 80 years were included in this study.Intervention(s):Concentric and eccentric peak torque of quadriceps and hamstring muscles were evaluated for all individuals in patient and control groups with a Cybex isokinetic device. Functional H/Q ratio is calculated manually.Main Outcome Measure(s):Functional H/Q torque ratios were analyzed between the patients with OA and healthy individuals by using the isokinetic system.Results:The values of peak torque of hamstring concentric and eccentric and quadriceps concentric for the patient group were significantly lower than the control group (P < .05). No statistically important difference was found for quadriceps eccentric peak torque between 2 groups (P > .05). H/Q ratio for extension in the patient group was significantly higher than the control group (P < .05), whereas the H/Q ratio for flexion in the patient group was significantly lower than the control group (P < .05).Conclusion:This study showed the weakness of both quadriceps and hamstring muscles in patients with knee OA. The combination of functional H/Q ratio with hamstring and quadriceps muscles concentric and eccentric strength values can help to analyze the knee functions and develop preventive-therapeutic approaches for knee OA.
Sensitivity of a western Great Basin terminal lake to winter northeast Pacific storm track activity and moisture transport
Authors: Hatchett Benjamin J. , Boyle Douglas P. , Garner Chris B. , Kaplan Michael L. , Bassett Scott D. , Putnam Aaron E.
Published: October 2019

Shorelines formed by terminal lakes record past changes in regional moisture budgets. In the western Great Basin of North America, winter precipitation accounts for nearly half of the annual total and is well correlated with northeast Pacific storm track activity and moisture transport. We evaluated these relationships and found that historical precipitation between 1910 and 2012 was better correlated to moisture transport (0.78, p < 0.01) than to storm track activity (0.54, p < 0.01) because moisture transport better captures dynamics associated with the Sierra Nevada rain shadow. We derived modern analogs of enhanced and reduced storm track activity and moisture transport from reanalysis products and used associated winter precipitation anomalies with these analogs as inputs to a coupled water balance and lake evaporation model of the Walker Lake basin. Simulated lake-level responses were compared with a radiocarbon-dated lakeshore chronology spanning the past 3700 yr. Wet analogs developed from winters in the 90th and 75th percentiles for storminess and moisture transport produced lake levels that exceeded estimated late Holocene highstands by 50 m. Dry analogs (10th and 25th percentiles) produced lake levels corresponding to Medieval megadrought lowstands. The twentieth century is shown to be as wet as any century in the past 3700 yr. Our results demonstrate the sensitivity of terminal lakes to winter season circulations and highlight the value of using moisture transport as a predictor of cool season precipitation and to evaluate how past or future changes in regional circulations will influence the water balance of dryland regions.
Perspectives on the paleolimnology of the late Eocene Florissant lake from diatom and sedimentary evidence at Clare’s Quarry, Teller County, Colorado, USA
Authors: Benson* Mary Ellen , Smith Dena M. , Spaulding Sarah A.
Published: October 2019

The late Eocene Florissant Formation in central Colorado is a rich and diverse continental Lagerstätte yielding well-preserved fossil assemblages from lacustrine and fluvial facies. This investigation focused on the lacustrine facies at Clare’s Quarry and used biotic and abiotic evidence to characterize aspects of the lake and processes that resulted in the accumulation and preservation of the host rock and its fossils. Autecology of modern analogs representing the fossil diatom taxa was used to augment sedimentary data in characterizing the lake, propose peripheral habitats within the catchment area, and suggest a terrestrial source for mudstone units.

The sedimentary and stratigraphic record at the study site reveals a lake with sufficient depth to allow bottom waters to remain isolated and anoxic for long periods. Sediments that accumulated in the lake produced distinct lacustrine lithofacies that are interpreted as representing at least three modes of origin: stable lake, pyroclastic, and mud turbidite sedimentation. Slow, suspension settling of fine clays and volcanic ash into a moderately deep, stable lake resulted in laminated shales. These laminated shales contain frustules of diatoms from planktic and benthic lake habitats; diatoms transported into the lake from streams and wetlands; fish, mollusks, ostracods, and insects; and plants from marginal and upslope environments. Intermittent volcanic eruptions produced air-fall ash and granular tuff that accumulated as interbeds within the lake shales. Periods of stable lake sedimentation were frequently interrupted by rapid influxes of suspended fine clays, perhaps as mud-dominated turbidites that prograded into the lake at intervals of high runoff triggered by climatic, volcanic, or tectonic events.