bluuebunny/crossref_metadata_2025 huggingface dataset:
A SIMPLIFIED SUSTAINABLE MANUFACTURING PARADIGM FOR SMALL SCALE GOLD PRODUCTION SYSTEMS
Authors: Soriano Virginia Jose
Published: June 2024

The Philippine gold industry has contributed largely to the country’s economy by generating and supporting thousands of small scale industries in mining, processing and jewelry manufacturing. However, small-scale gold production in the country is described as an informal industry with minimal standards, thus affecting their competitiveness and sustainability. This study aims at using a simplified paradigm that integrates the economic, environment, technology, legal and social aspects for sustainability in gold manufacturing. The study used life cycle thinking and systems approach to assess the impact of current practices on the said aspects of the small scale gold production activities. The assessment results showed the important sources of environmental burden, inefficiency, technological and social impacts. Further, through literature review and interviews of industry stakeholders, the identified issues and concerns include the availability of channels to access miner’s information, trainings, technology and programs for cleaner and more efficient production, as well as clear and specific environmental legislation and regulations. Finally, the study identified opportunities that could potentially improve and balance sustainability goals of the small scale gold manufacturing industries.
BIODIESEL FUELS CONVERSION TO HYDROGEN-RICH GAS AND ELECTRICITY WITH SOLID OXIDE FUEL CELL TECHNOLOGY
Authors: Tran Quang-Tuyen , Shiratori Yusuke , Sasaki Kazunari , Nguyen Ngoc Dung , Reksowardojo Iman Kartolaksono , Brodjonegoro Tirto Prakoso
Published: June 2024

Direct feeding of hydrocarbon fuels to Solid Oxide Fuel Cells (SOFCs) has attracted much attention in recent years. The aim of this paper is to investigate the viability of anode-supported type cells (NiScSZ/ScSZ/LSM-ScSZ) operating with biodiesel fuels (BDFs) derived from Palm, Jatropha and Soybean oils, for realizing carbon-neutral power generation using fuel cells in the temperature range of 700 - 800oC. The results demonstrated that in principle direct internal reforming (DIR) of BDFs in the SOFC anode is viable, but the content of unsaturated components in BDFs should be as lower as possible to suppress performance degradation. Palm-biodiesel, containing highest amount of saturated fatty acid methyl ester (FAME) among tested BDFs, had led to most stable SOFC operation, and the amount of deposited carbon was considerably small compared to the other fuels with higher degree of unsaturation.
REGRESSION-BASED OPTIMIZATION OF THE PARTIAL OXIDATION OF METHANE ON NIMGO/Α-ALUMINA MONOLITH CATALYST IN A REVERSE-FLOW REACTOR
Authors: Nguyen Trung Kim , Razon Luis , Tan Raymond , Tran Hai-Ung , Hinode Hirofumi , Aida Takashi
Published: June 2024

This study describes the use of statistical optimization techniques on a laboratory scale reverse flow reactor for the catalytic partial oxidation of methane on Ni-MgO/α-alumina monolith catalyst. The effects of initial temperature (Tini), switching time (τ), total flow rate (F), mole fraction of methane (M), and catalyst length on hydrogen yield and methane conversion are investigated using systematic experimental design. In the first experimental phase, the steepest ascent path was established by ridge analysis to determine the stationary point. The optimum operating conditions were determined in the second experimental phase. The following interactions were found to be significant for methane conversion: M*τ, F*τ and M*F. The interaction of F*τ also affected the hydrogen yield. The third-order interaction of F*τ*M was also found to be statistically significant. The optimum methane conversion value of 57.36% could be obtained by setting switching time, total flow rate and a mole fraction of methane of 4.24 minutes, 543ml/min and 0.6043, respectively. The optimum value of hydrogen yield of 36.73% was reached by setting total flow rate, mole fraction of methane and switching time of 540ml/min, 0.5845 and 4.15 minutes, respectively. The analysis of reactor operation showed that optimization of the system required changing more than one factor and that there is a complex interplay of the different experimental factors. The influence of the factors may all be interpreted in terms of heat release and heat loss in the system.
EFFECT OF DIFFERENT ORIGINS OF NATURAL RUBBER ON THE PROPERTIES OF CARBON BLACK FILLED NATURAL RUBBER COMPOSITES
Authors: Phanny Yos , Azura Rashid , Ismail Hanafi
Published: June 2024

Two different origins of natural rubber (NR) from Malaysia; SMR CV60 and Vietnam; SVR 3L filled with 0 and 30phr carbon black (CB) were investigated. Compounds were prepared by a two-roll mill with conventional (CV) and efficient (EV) cure systems. Results obtained show that SVR 3L has higher Mooney viscosity compared to SMR CV60. A different origin of NR has influenced the cure characteristics of rubber compounds. In EV system, SVR 3L compounds showed faster cure rate index (CRI) while in CV system showed contrary results. However, CRI of NR compounds with EV system increased with addition of CB due to high amount of accelerator while CRI in CV system decreased with addition of CB. Torque difference for both NR compounds with each cured system showed similar value. However, mechanical and physical properties were dependent on addition of CB. SVR 3L composites exhibited better tensile strength and recovery from loading force compared to SMR CV60.
INTEGRATION OF OCEAN COLOR DATA, THERMAL SENSOR DATA AND ENVIRONMENTAL PARAMETERS FORASSESSMENT OF PRODUCTIVITY OF THE COASTAL WATER
Authors: Khaing Myint Myint , Mishra Akhil Kumar
Published: June 2024

Oceans occupy almost 70% of the Earth’s surface, which play an important role in the climatic conditions of the adjacent land regions. In the ocean, the physical, chemical, and biological processes are linked in an intimate manner. Oceanic features such as chlorophyll concentration, current boundaries, sea surface temperature, ocean fronts and eddies, suspended particulate matter, and dissolved organic matter influence the ocean environment in a complex manner. Satellites are used as an important tool for better understanding of the marine processes, ecology, and the coastal environment. In the present study the in situ data collected off Goa, west coast of India, the World Ocean Atlas data and the satellite data have been taken for analysis. The main data base consists of phytoplankton, Nitrate, Phosphate, Silicate, Temperature, Oxygen and pH which collected by the month of November, 1999. The surface and bottom data have been averaged to represent the mean concentration of the mixed layer depth of the region. Appropriate weightage have been assigned to the chemical, biological and physical parameters to find out the productive regions. The in-situ data and the World Ocean Atlas data have been integrated and analyzed to produce the final Productivity Map off Goa, west coast of India. The NOAA-AVHRR data of the month of April 2003 has been used for retrieval of sea surface temperature. The phytoplankton concentration map of same day from IRS-P4(OCM) data has also been used for analysis. The OCM data and AVHRR data have been analyzed for identification of Productive Zones of the coastal regions which will be a helpful methodology for Potential Fishing Zone (PFZ) prediction.
COD AND NITROGEN REMOVAL OF AEROBIC GRANULAR SLUDGE IN SEAFOOD PROCESSING WASTEWATER TREATMENT
Authors: Nguyen Phuoc-Dan , Bui Xuan-Thanh , Nguyen Trong-Luc
Published: June 2024

Aerobic granule was formed and stably in the sequencing batch airlift reactor with the seafoodprocessing wastewater at different organic loading rates (OLR) and nitrogen loading rates (NLR). At the N/COD ratio of 0.1, the COD removal efficiency was ranging from 94 to 96 % for OLR of 2.6 – 7.2 kg COD/m3 .d. The TKN removal efficiency was 93, 94 and 79 %, respectively. At the varied N/COD ratios, the TKN removal efficiency was approximately 95 % for the NLR of 0.3 and 0.6 kg N/m3 .d (N/COD of 0.1-0.2). The TKN removal efficiency reduced to 66% at the NLR of 0.9 kg N/m3 .d. In general, nitrification process occurred completely at the OLR less than 4.8 kg COD/m3 .d and the NLR less than 0.6 kg N/m3 .d. The simultaneous organic and nitrogen removal was effective at the OLR of 2.6-4.8 kg COD/m3 .d and the NLRs of 0.3 - 0.6 kg N/m3 .d.
MAGNETIC SUSCEPTIBILITY AND GEOCHEMISTRY OF GRANITIC ROCKS IN CAMBODIA
Authors: Kong Sitha , Watanabe Koichiro , Imai Akira
Published: June 2024

Granitic rocks in Cambodia are divided into two groups, i.e. ilmenite-series in southern Cambodia and magnetite-series in northern Cambodia. Both groups belong to high-K calc-alkaline series, metaluminous to slightly peraluminous and display typical features of I-type granitic rocks. The ilmenite-series granitic rocks are characterized by high SiO2 contents (70-75 wt. %) with abundance of quartz and K-feldspar, enrichment of LILEs, and strong negative anomalies of Ba, Sr, Eu (Eu/Eu*=0.1-0.5), Nb, and Ti. Chondrite-normalized REE patterns exhibit enrichment of LREE ([La/Yb]N=1.4-17.6) with flat HREE patterns and flat to concave-upward MREE patterns. These granitic rocks have high CaO+FeO+MgO+TiO2 and intermediate Al2O3/(FeO+ MgO+TiO2) with intermediate magnesium number (Mg# = 22-38) (Mg# = 100 x MgO/[MgO+Total FeO]). Geochemical features of the granitic rocks suggest partial melting of crustal igneous rocks of intermediate composition where plagioclase was a major fractionating and/or residual phase. On the other hand, the magnetite-series granitic rocks show wide range of SiO2 contents (59-70 wt. %), higher TiO2, Al2O3, CaO, and MgO contents than ilmenite-series granitic rocks, and smallnegligible negative anomalies of Sr and Eu. The high CaO+FeO+MgO+TiO2 and low Al2O3/(FeO+ MgO+TiO2) coupled with high Mg# (32-48) suggest partial melting of amphibolite-type source with presence of plagioclase. The granites of Cambodia were formed in subduction-related tectonic setting. The ilmenite-series granites range from volcanic-arc granites to syn- and postcollision granites while the magnetite-series granitic rocks belong to volcanic arc granites.
SYNTHESIS AND CHARACTERIZATION OF PIGMENT CoxNi1-xAl2O4
Authors: Ha Huynh Ky Phuong , Salim Chris , Hinode Hirofumi , Anh Nguyen Tuan , Vien Le Minh
Published: June 2024

Pigment CoхNi1−хAl2O4 have advanced properties for application in industrial scale such as the reduction in production cost and environmental damage, the stability in physicochemical characteristics. In this study, pigment CoхNi1−хAl2O4 (where x= 0.2, 0.5 and 0.8) was synthesized using the organic precursor method at low calcination temperature. The pigment was analyzed using XRD to determine its spinel structure as well its thermo-stability. The physicochemical properties of the pigment were determined including pH (7.11-7.63), density (3.43 – 4.19), coverage rate (47.67 – 48.9 g/m2 ), and oil adsorption (42-45 g of oil / 100 g pigment). SEM result shows that the crystalline structure of the synthesized pigment is almost homogeneous and lies within the nanosize range. The characterization shows that the pigment was successfully synthesized at nanosize and has potential for applications in the industry.
STUDY ON RHEOLOGICAL AND THERMAL PROPERTIES OF TREATED WASTE NATURAL RUBBER LATEX/POLYSTYRENE BLEND AS REDUCTANT
Authors: Boondamnoen Orathai , Azura Rashid , Ohshima Masahiro , Chuayjuljit Saowaroj , Ariffin Azlan
Published: June 2024

The waste natural rubber latex (WNRL) was treated by natural rubber latex (NRL) to improve the properties. The treatment was done prior to blending with polystyrene (PS). The preparation of treated waste natural rubber latex (TWNRL)/PS was conducted with ratio of 70/30 using internal Haake mixer at 140ºC with speed of 60 rpm. The WNRL/PS blend was prepared in a similar way for comparison purpose. The mixing torque was recorded during blending, while storage modulus and tan_delta were investigated using Rheometer. The thermal gravimetry (TG) and difference scanning calorimeter (DSC) were also studied. The results showed that TWNRL/PS blend gave lower mixing torque compared to WNRL/PS blend. Thus, it reveals that the treatment of WNRNL by NRL could improve the processibility. The storage modulus of TWNRL/PS blend showed lower value compared to WNRL/PS blend. This could be due to that the TWNRL/PS blend contains lower cross-linked molecules which have lower resistance to chains mobility. A study using DSC implied that TWNRL and PS are immiscible (two-phase system). This can be proven by the presence of two glass transition. In comparison, the Tg from DSC and tan_delta observed for TWNRL/PS and WNRL/PS blends showed no significant difference. However, the degradation temperature of TWNL/PS blend was slightly lower than that of WNRL/PS blend due to the requirement of energy for breaking the network molecule was lower.
ASSESSMENT OF WATER QUALITY VARIATIONS IN SAN JUAN RIVER USING GIS AND MULTIVARIATE STATISTICAL TECHNIQUES
Authors: Blanco Ariel , Alarilla Amado , Dimalibot Ricajay , Bonga Merliza , Paringit Enrico
Published: June 2024

Investigations of water quality variations need to consider the temporal aspect as well as the spatial aspect to better understand processes and identify control factors and facilitate the formulation of potentially effective measures to improve water quality. The water quality of San Juan River and its tributaries was assessed over a one-year period through monthly water sampling and 24-hour in situ measurements at 13 primary stations, bi-weekly in situ measurements at 30 stations and synoptic spatial water quality surveys along the rivers and creeks. Parameters monitored include turbidity, suspended solids, dissolved oxygen, various nutrient species, ORP, COD, BOD, coliforms and heavy metals. TSS, BOD, and COD variations showed seasonality effects: relatively high in January and February, gradually decreasing through the summer months, continually decreasing further during the rainy months of June to September, and increasing in October to December. The same was observed for Total Nitrogen, Nitrate-N and Ammonia-N. Based on COD and ORP, the Balingasa/Talayan Creek and Maytunas Creek are the most degraded in water quality. Coliforms at the 13 primary stations were all above 10,000,000 MPN. ORP values were largely negative at all stations. However, at most stations, except Balingasa/ Talayan and Maytunas creeks, ORP can become zero or positively valued due to dilution by rain and runoff. Agglomerative hierarchical clustering was used to groups the primary stations into classes of varying pollution severity. The delineated subwatersheds were characterized in terms land use, population and road density evaluated using GIS zonal analysis. Based on the factor analysis, the dominance high residential areas, industries, and informal settlements aggravate water quality with increased BOD, COD, nutrients and coliforms. Results from multiple linear regression indicate that COD levels are largely due to industries and informal settlements. The use of multivariate statistical analysis enabled a better assessment of water quality variations as well as the spatial variability of factors influencing water quality.
FINITE ELEMENT SIMULATION OF MIXED-MODE CRACK PROPAGATION BASED ON STRAIN ENERGY DENSITY CRITERION
Authors: Dinh Hung The , Lenwari Akhrawat , Senjuntichai Teerapong , Hayashikawa Toshiro
Published: June 2024

Prediction of crack growth path is pre-requisite for estimating the fatigue life of structures. A combination of loading, structural geometries and material properties can significantly influence the crack propagation. This paper presents finite element modeling of mixedmode crack propagation in two-dimensional linear elastic problems by adopting the strain energy density (SED) criterion. The main objective is to predict the path of crack growth under mixedmode conditions. According to the SED criterion, the crack path will follow the direction of minimum strain energy density factor. In finite element models, the ring elements are constructed around the crack tip at each crack propagation stage. Strain energy density values in the ring elements are then used to determine the direction of minimum strain energy density factor. Once the direction is known, an increment of crack propagation is assumed, and a new mesh with ring elements is generated for the next crack propagation stage. Examples are illustrated for comparisons with experimental results of two crack configurations, which are a plate with an inclined central crack and the modified compact tension specimen.
STUDY ON DECENTRALIZED DOMESTIC WASTEWATER TREATMENT BY CONSTRUCTED WETLAND VERTICAL - SUBSURFACE FLOW SYSTEM FOR SMALL COMMUNITIES
Authors: Tan Phong Nguyen , Vu Phuong Tieu
Published: June 2024

This research investigated the feasibility of using constructed wetland system with vertical - subsurface flow (VF-SFS) for treating the decentralized domestic wastewater for household and small community. The pilot studied on three beds included three macrophytes tested parallel reed, vetiver and bulrush with four different hydraulic application rates (176, 132, 88 and 44 mm/ day).This study was tested with six different parameters such as biochemical oxygen demand (BOD), total suspended solids (TSS), orthophosphate (PO43-), ionized ammonia (NH4+) and nitrate (NO3-) nitrogen and total coliform loadings. The removal rate of characteristic parameters was obtained: BOD5 96%, TSS 96.9%, N-NH4+ 60.5%, PO43- 47.6%, total coliform 97.7%, respectively. In particular, the highest removal efficiency was obtained in the bed with the longer hydraulic retention time. Simultaneously, there was no removal difference among 03 beds constructed wetland with 03 different plant species, significantly. Through the results of research, VF-SFS can be considered an appropriate treatment method for domestic wastewater; however the additional pre-treatments were necessary to remove grit, heavy solids and floating scum.
MINERALOGY AND ORIGIN OF COPPERGOLD BEARING SKARN WITHIN THE BATU HIJAU PORPHYRY DEPOSIT, SUMBAWA ISLAND, INDONESIA
Authors: Aye May Thwe , Pramumijoyo Subagyo , Idrus Arifudin , Setijadji Lucas Donny , Imai Akira , Arif Johan , Kepli Symsul
Published: June 2024

The aim of this study ist o emphasize on the origin of copper-gold bearing skarn mineralization at the Batu Hijau deposit which is located at the southwestern corner of Sumbawa Island, Indonesia. Although most skarn are derived from limestones, nolimestone is known in the Batu Hijau deposit. Ca-rich andesitic volcaniclastic host rocks favor skarn alteration within the Batu Hijau deposit. The t ype of skarn can be classified as calcic-exoskarn, and locally controlled by faults and fractures. Two major stages consisting of four sub-stages of skarn forming processes can be divided by the mineral assemblages of skarn as prograde and retrograde stages. The prograde skarn consists of clinopyroxene and garnet ± magnetite formed at the trapping temperature of 440°-480 °C with 34-38 wt% NaCl eq. while retrograde skarn alteration is dominated by Fe-rich minerals such as amphibole and epidote formed at the trapping temperature down to 340°-360°C with 4-8 wt% NaCl eq. Opaque minerals include chalcopyrite, pyrite, sphalertite, and minor galena and bismuth- telluride. Gold was precipitated in the retrograde stage associated with bismuthtelluride minerals. The sulfur isotope data of skarn ranges from +0.1 to +1.7‰ (sulfide), and porphyry systems range from 0.04 to1.4‰ and 10‰ to 15‰ (sulfide and sulfate respectively). According to the fluid inclusion and sulfur isotope data, the origin of skarn and porphyry system can be suggested to be that the magmatic origin. Furthermore, the sulfur isotope data of the deposit evidently shows that a porphyry- related skarn mineralization exhibiting transition from one style to the next can be relatively rapid. The result of this research has indicated that the range of porphyry-related deposits, skarn and porphyry systems can form during a single prolonged hydrothermal event.
IDENTIFATION OF LANSLIDE DIMENSION BASED ON SEISMIC REFRACTION SURVEY IN TENGKILK VILLAGE, KARANGANYAR, CENTRAL JAVA
Authors: Wilopo Wahyu , Karnawati Dwikorita
Published: June 2024

A seismic refraction survey was conducted at a landslide site, which had destroyed a road and several houses in Tengklik Village, Karanganyar, Central Java, Indonesia. The survey provided insight into the slope stratigraphy, as well as the dimensions of sliding area and depths of the slope failure planes. Field observations and drill-hole data were used to verify the accuracy of seismic refraction data. The seismic velocity measured in the top - sliding layer of sandy silt was less than 900 m/sec, while that in the underlying layer of silty sandstone ranged from 2400 to 900 m/sec. The stable bedrock of andesite breccia underneath the sliding soil layers was about 2500 m/sec. It was apparent that the failure surface was irregular, varies in depth. This failure plane exists at the contact of the andesitic breccia (bedrock) and the sliding layer of silty sandstone. The thickness of the sandy silt ranged from 3 to 5 m at lower part of sliding mass, while at the upper part ranged from 4 to 8 m. The estimated depth of the failure surface ranged from 12 to 24 m. The volume of mass movement is estimated about 111.386 m3 . It was also found that the presence of mountain block at the bedrock of andesitic breccia may resist the movement.
NITIAL APPROXIMATION FOR NEWTON-RAPHSON ITERATION TO CALCULATE 4 THE NEUTRAL AXIS POSITION OF GLULAM BAMBOO
Authors: Irawati Inggar Septhia , Suhendro Bambang , Saputra Ashar , Prayitno Tibertius Agus
Published: June 2024

Glued laminated (glulam) bamboo has possibility to be used as construction material. For structural purpose, an analytical calculation is needed to estimate the structure capacity. As bamboo typically has non linear material behavior under compression parallel to grain, it is essential to figure out the non linear behavior of glulam bamboo for structural component. The research purpose is to figure out non linear behavior of glulam bamboo by determining maximum capacity under axial and lateral loadings according to actual properties of tension and compression parallel to grain. The failure load is numerically computed based on finite different method. A Newton-Raphson iterative procedure is employed to determine the deflection curve and neutral axis position that meet the equilibrium condition. Assumption used is that tensile or compressive stress is equal to zero when it is greater than its ultimate stress. This paper is focused to describe iterative procedure to obtain neutral axis position. The novelty of this study is the proposed initial approximation for iteration of neutral axis position which has never strongly been considered by previous study. Its application and detail discussion are presented. There are two reasons why initial approximation for obtaining neutral axis position is important to be understood. First, it influences the speed of convergence, and secondly, when the internal stress is close to the maximum strength, it might influence the convergence of calculation.
REMOVAL OF MANGANESE IN CONTAMINATED GROUNDWATER BY PERMEABLE REACTIVE BARRIERS USING COMPOST AND ZERO VALENT IRON
Authors: Wilopo Wahyu , Putra Doni Prakasa Eka , Hirajima Tsuyoshi
Published: June 2024

Sorption and precipitation of manganese in groundwater remediation using compost and zerovalent iron (ZVI) were investigated by batch and column experiments. In batch tests, compost is more effective than ZVI to immobilize manganese, with the maximum removal of 238.09 mmol Mn. kg-1 of compost according to Langmuir equation. High efficiency of Mn removal onto compost is probably not only by physical sorption but also by surface complexation with carboxylic groups in the compost. This result was confirmed with FTIR data that shown new peaks at 675 cm-1 after contacted with manganese solution. Manganese was also immobilized through sorption onto ZVI due to high surface area, and partly by precipitation as manganese oxide because of intense alkalization. In column materials, after introducing manganese solution for 36 pore volumes (pv), manganese was predominantly immobilized in upper part of the column. It is considered that compost was degraded and the surface of ZVI granules was already uniformed and corrosion products are the most accumulated on ZVI granules near the inlet because ZVI has been contacted with high concentrations of manganese for the longest time in the most bottom parts. This was also supported by XRF data from ZVI grains that manganese was the largest in the most bottom segment. The results of geochemical calculations along with the SEM image suggest that partly of manganese were also precipitated with carbonates. The result demonstrates that combination of compost and ZVI is more effective to remove manganese than using single material due to the different mechanism of removal from each material.
REMEDIAL STRUCTURES TO STABILIZE LONG XUYEN RIVERBANK TO PREVENT SLIDING IN AN GIANG PROVINCE,VIETNAM
Authors: Tran-Nguyen Hoang-Hung , Nguyen Du Ngoc
Published: June 2024

Sliding of structures along riverbanks in An Giang province has caused serious losses for local people and the current stabilized methods have been ineffective to treat sliding issues sustainably. This study attempts to propose some remedial methods to prevent sliding of structures along the Long Xuyen riverbank in An Giang. These structures were designed, constructed at the selected sites, and monitored their field performance for a flood cycle which is a year. The two stabilized structures were proposed, analyzed, and successfully constructed at the two selected sites. The field monitoring instruments such inclinometer casing and groundwater observation wells also were fully installed to obtain the field data to evaluate field performance of the proposed structures.
EROSION MECHANISM OF NGA BAY RIVERBANKS, HO CHI MINH CITY, VIETNAM
Authors: Vinh Bui Trong , Truong Nguyen Hai
Published: June 2024

Nga Bay river is a main river navigation channel from East Sea to Sai Gon port. Although Nga Bay riverbanks are covered by dense mangrove trees, those have been eroded severely. Field investigation, GIS and numerical model (MIKE 21) were carried out to determine and analyze the erosion mechanism in this river mouth. The actual erosion rate was determined by erosion investigation stakes was about 10 m/y. These results corresponded with GIS analyses. The main destroyed factors were currents, waves and ship-generated waves. However, mangrove trees were the main protected factors destroyed by local population for economic activities. The numeral results showed that current speed around river mouth area is stronger than critical resistance of riverbank materials and caused severe erosion.
APPLICATION OF GENETIC ALGORITHM OPTIMIZATION FOR ORGANIC RANKINE CYCLE WASTE HEAT RECOVERY POWER GENERATION
Authors: Riyanto Hendi , Martowibowo Sigit Yoewono , Maksum Habibie
Published: June 2024

Waste heat recovery for power generation has lately been widely practiced in process industries. A cement plant of 8,300 ton per day capacity releases 17.5 MWth of flue gas at 360oC to 225oC from its suspension preheater (SP) and 28.0 MWth of hot air at 310oC to 122oC from its air quenching cooler (AQC). The temperature of waste heat from a cement plant is in the lower bound of performace criteria to employing Claussius Rankine cycle (steam power cycle), therefore, organic Rankine cycle (ORC) can alternatively be applied for power generation. Finding the optimum solution of the design pressure and temperature of the ORC for waste heat recovery for power generation (WHRPG) corresponding to the most suitable working fluid is the aim of this study. Genetic algorithm (GA) is being considered for the method to determine the optimum solution. In addition, the technique for order of preference by similarity to ideal solution (TOPSIS) is applied to select the best matched working fluid for the ORC. According to TOPSIS evaluation, amongst four working fluid considered, i.e., isobutane, isopentane, benzene, and toluene, isopentane is ranked at the top in terms of health, safety, environment, power output, and cost critera. The optimum ORC WHRPG design is capable of producing 6,094 kW of electric power with AQC boiler pressure of 11.09 bar-a, SP reheater pressure and temperature of 3.68 bar-a and 184oC, and recuperator and condenser pressure of 1.27 bar-a. The highest pressure of 11.09 bar-a at HP turbine and the highest temperature of 184oC at the LP turbine are relatively low compared to that of steam Rankine cycle power plant, thereby dictate less stringent mechanical and thermal strength of materials requirement.
MEASUREMENT OF STRUCTURE-BORNE NOISE FROM ROAD INPUT IN A MOTOR VEHICLE CABIN
Authors: Putra Azma , Wong Hee Kiong , Jalil Nawal Aswan Abdul
Published: June 2024

Vehicle interior noise has been an important aspect to determine quality of a vehicle since it affects the level of acoustic comfort of the passengers. This paper proposes a simple noise measurement technique to quantify the contribution of the structure-borne noise due to tire-road interactions. A subcompact sedan was used as the test vehicle in this study. The Sound Pressure Level (SPL) inside the cabin was measured in two conditions – i) laboratory test when the test vehicle was running on a dynamometer and ii) field measurement. In the laboratory measurement, the SPL was measured at the engine speed of 1000, 2000, 3000 and 4000 revolutions per minutes (RPM). In the field measurement, the SPL was measured when the test vehicle was running at a steady RPM and the vehicle speed in the range of 60 to120 km/hr. The results showed that there was a profound contribution of structure-borne noise from the tireroad interaction and aerodynamic excitation at frequency below 400 Hz. It can be concluded that the structure noise-born in a vehicle is possibly contributed from road input interaction, vehicle suspension system and aerodynamic excitation on the vehicle.
DEVELOPMENT OF FLOOD ROUTING MODELS FOR WANG RIVER BASIN
Authors: Komsai Atchara , Liengcharernsit Winai , Kinouchi Tsuyoshi
Published: June 2024

Nowadays, severe flooding frequently occurs in various parts of Thailand resulted from changes in climatic condition and land use patterns. The flooding has caused great damages to properties and lives and affects country economy. Experience from the most severe flooding in the northern and central regions of Thailand in the year 2011 reveals that reliable flood warning system is still lagging. For flood warning purpose, it is necessary to have an accurate flood routing system. This study is aimed at developing mathematical models for flood routing so as to provide data for flood warning. Two different models are developed, i.e., kinematic overland flow model and kinematic stream flow model. The finite element method with Galerkin’s weighted residual technique is used in model development. The second-order Runge-Kutta method is applied to solve the set of differential equations obtained from finite element formulation. The developed models are applied to simulate flows in the Wang river basin in the northern region of Thailand during July 1 – October 31, 2011 when severe flooding occurred in this region. Model calibration is made by adjusting some parameters in the models and comparing the obtained results with measured data recorded by RID at 5 stream flow gauge stations along the Wang river. For correlation analysis, three statistical indices are determined, these include coefficient of determination, R2 , Nash–Sutcliffe model efficiency coefficient, NSE, and coefficient of variation of the root mean square error, CV(RMSE). It is found that the model results at the upstream portion of the river satisfactorily agree with the observed data, with the values of R2 greater than 0.55 and CV(RMSE) less than 0.57. For the downstream portion of the river, there are remarkable differences between the model results and the observed data. The values of R2 are less than 0.35, CV(RMSE) greater than 0.76, and the NSE values are less than 0.16. This might be due to some errors in the input data, including rainfall pattern, topography, land use, river cross-sectional area, and water seepage along the river. More detailed field investigation and model calibration are still needed.
MODELING DISTRIBUTED HYDROLOGICAL AND SEDIMENT PROCESSES TO ASSESS LAND USE EFFECTS IN CHAO PHRAYA RIVER BASIN
Authors: Tanuma Kazuki , Suif Zuliziana , Komsai Atchara , Liengcharernsit Winai , Valeriano Oliver Cristian Saavedra
Published: June 2024

Soil loss and its transport processes were coupled with an existing distributed hydrological model to assess the effects of land use change on stream flow and suspended sediment load in the Chao Phraya River basin, Thailand. The simulation period spanned from 2001 to 2010. The results indicate that the Nash–Sutcliffe efficiency of upper sub-basins fluctuated in the range 0.51–0.72, indicating the applicability of the model for long-term simulation at the monthly scale. Land use change during 2001–2010 caused a 1.6% increase in suspended sediment load based on the present trend. The changes were particularly pronounced in the Wang River basin, where the delivery ratio was highest. Moreover, the urbanization and conversion of farm land from paddy fields exerted negative effects on sediment runoff in Chao Phraya River basin. The proposed model has the ability to quantitatively evaluate the heterogeneity of sediment runoff in the basin, demonstrating the benefits and trade-offs of each land use change class. The results of this study can support basin and local land development policy to control sediment losses during development.
DISTRIBUTION AND ECOLOGICAL RISK ASSESSMENT OF PLASTICIZERS IN THE CHAO PHRAYA DELTA, GULF OF THAILAND
Authors: Sirivithayapakorn Sanya , Thuyviang Kanjana , Jansak Prachaya
Published: June 2024

Preceding monitoring reports indicated that di (2-ethylhexyl) phthalate (DEHP), a common plasticizer, was found in the samples of suspended sediment and water collected from the lower part of Chao Phraya River. In this continuing study, the suspended sediment and water samples from the Chao Phraya Delta were collected twice a year in January and July during January 2011 – July 2013. The analyses were performed for both DEHP and Diethyl Phthalate (DEP). Overall results showed that concentrations of both DEHP and DEP in the water samples were relatively higher than those in the suspended sediment samples. The concentrations of DEHP and DEP from all sampling periods in the water samples ranged from 1.58 – 27.55 µg/L and from 0.64 – 2.59 µg/L, respectively, whereas the concentrations of DEHP and DEP from all sampling periods in the suspended sediment samples ranged from 0.01 – 26.82 mg/g and from 0.01 – 1.93 mg/g, respectively. The concentrations of both DEHP and DEP in both suspended sediment and water samples were relatively higher in the samples collected during lower discharge period of the Chao Phraya River in July. The results indicated that sediment transport system could play an important role in the dispersion of both DEHP and DEP. The ecological risk assessment indicated that for the current level of contaminations the risk did not exceed the acceptable level.
EVALUATION OF FIELD PERFORMANCE OF PREFABRICATED VERTICAL DRAINS (PVD) FOR SOIL GROUND IMPROVEMENT IN THE SOUTHERN VIETNAM
Authors: Tran-Nguyen Hoang-Hung , Ho Huong , Ha Hy Hoan
Published: June 2024

A 40,000-km2 soft ground area in the southern Vietnam is big obstruction for infrastructure development in Vietnam. PVD is the most popular technique applied to improve soft ground in the southern Vietnam. However, field performance of PVD based on field monitoring is quite discrepant from prediction. This study aims at better understanding of PVD field performance via case studies. The two complete projects using PVD for soft ground improvement were utilized for back analysis. Field monitored settlements agree well with predicted settlements when the field settlement has experienced a settlement of 0.3 m or less. The predicted settlement exceeds the field monitored settlement about 50% when the field settlement reaches 0.5 m or larger. The result indicates that degree of filed consolidation was less than 90%, and large field settlement keeps occurring during the service stage of highway embankments and may cause field settlement over the allowable settlement according to the Vietnam Code for soft ground improvement.
EXPERIENCES IN NUMERICAL ANALYSES OF SURFACE CHARGE ON INSULATORS EXPOSED TO HIGH VOLTAGE IN VACUUM
Authors: Yamamoto Osamu
Published: June 2024

This paper deals with the electrical insulation of a gap bridged by a solid dielectric between a pair of electrodes in a vacuum, where the dielectric is a model of an insulating spacer holding electrodes in various vacuum devices. Such gap configuration is typical as a model for studying physical mechanisms of an electrical breakdown or a flashover in a vacuum, in which the insulation ability is considerably lower than a gap without any insulating spacers. Many researchers have long investigated the mechanisms of flashover, and it is believed that the charging of the insulator surface is the primary drive of such weakness. One of the effective approaches for studying mechanisms is to analyze the characteristic of charge accumulated on the insulator surface both by experiments and by numerical analyses. This paper reviews previous works conducted by the author’s research group and demonstrates the difficulties we have encountered upon conducting the numerical analyses.
IMPLEMENTATION OF LOW COST FPGA REMOTE LABORATORY
Authors: Hoang Thang Manh , Quang Huy Nguyen , Hung Tran Quang , De Souza-Daw Tony , Ngoc Le Hoang , Dzung Nguyen Tien , Bien Pham Huu
Published: June 2024

Traditional laboratories are being complemented by virtual and remote laboratories. Students attend traditional laboratories in class and after hours perform experiments remotely, often from their home. There have been several remote laboratories that have been developed for a range of disciplines. This paper proposes a remote laboratory for teaching FPGA and HDL at low cost. The remote laboratory is made of one server and multiple remote hardware sets. Each remote hardware set consists of one control board and at least one FPGA board. The Altera Development and Education (DE) Board is based on the Cyclone II 2C20 FPGA and is physically connected to the control broad. Both boards communicate with a computer server. The control board relays the FPGA inputs/outputs to the server, which in turns sends the status of the outputs to the client over the Internet to visually display the results. Students use a computer client to perform experiments remotely on the FPGA. This architecture is designed to have high scalability and low data bit rate communication link with the average client requiring only a data rate of 450B/s. A FPGA board is planned to be used as a traditional laboratory during day and reassemble with a control board and a server to become a remote laboratory at night.
MICROSTRUCTURE AND MICROHARDNESS OF NANO/ULTRAFINE (n/UFG) GRAINED COLDROLLED 0.06C STEEL
Authors: Nordala Phoumiphon , Yusop Nurul Khalidah , Othman Radzali , Ismail Ahmad Badri
Published: June 2024

This present study is aimed to examine the microstructure and microhardness of nano/ultrafine grained (n/UFG) of 0.06C steel which had been cold-rolled, quenched and annealed. The process started with three different initial microstructures with the condition of 1) austenization at 1000°C for 30 min soaking and air cool (AC), 2) austenization at 1000°C for 30 min soaking and ice-water quench (IQ) and, 3) same treated as IQ but the quench specimen was tempered at 750°C for 30 min soaking and icewater quench once again (IQT). All quenched specimen, then cold-rolled by 75% and annealed at different temperatures ranging from 500°C to 600°C for 30 min soaking. From the analysis, it was found that the specimens annealed at 550ºC exhibit nano/ultrafine ferrite grained size with similar microhardness value for AC, IQ, and IQT. It has also found that acceptable UFG microstructure formed with of IQT specimen performs faster that IQ and AC specimens in terms of microstructure recovery, re-crystallization and grain growth during annealing after cold rolling.
IMPACTS OF RISK FACTORS ON THE PERFORMANCE OF PUBLIC-PRIVATE PARTNERSHIP TRANSPORTATION PROJECTS IN VIETNAM
Authors: Sy Do Tien , Likhitruangsilp Veerasak , Onishi Masamitsu , Nguyen Phong Thanh
Published: June 2024

The rapidly increasing demand and the inefficacy of financing transportation infrastructure project investments have contributed to various challenges for Vietnam in recent decades. Since the country’s budget is inadequate for investing in all necessary infrastructure projects, the Vietnam government has been inviting other economic sectors, especially the private sector, to participate in infrastructure development. The cooperation between the government agencies and the private entities, called Public-Private Partnership (PPP), must encounter various challenges leading to difficulties in attracting private investors. A main reason is that private investors must deal with critical risks concerning PPP investment environment. It is a challenging task for the government to optimally manage such risks to enhance the attractiveness of PPP projects for private investors. This paper examines the critical risk factors that influence the private sector’s investment decisions on PPP transportation projects in Vietnam. Risk factors inherent in typical PPP projects were compiled by comprehensive literature review. To reflect unique characteristics of PPP projects in Vietnam, the compiled risk factors were reviewed by a group of PPP experts from both the public and private sectors in Vietnam through in-depth interviews and questionnaire surveys. In addition, ten PPP project case studies in Vietnam were analyzed to derive the risk profile of PPP transportation projects of the nation. These risk factors were quantitatively assessed based on their probabilities and impact levels. We found that the critical risk factors of PPP infrastructure projects in Vietnam are acquisition/compensation problems, approvals and permits, inadequate feasibility studies, finance market issues, subjective evaluation methods, and change in laws and regulations. By performing factor analysis, these critical risk factors were grouped into four categories: (1) bidding process, (2) finance issues, (3) laws and regulations, and (4) project evaluation issues. These critical risk factors represent the obstacles that repel private investors from PPP transportation projects in Vietnam. Thus, the Vietnam government agencies should meticulously address these issues to attract both domestic and foreign private investors in PPP projects.
TUNEABLE FIBER LASER USING SINGLE WALLED CARBON NANOTUBES BASED SATURABLE ABSORBER AND AWG AS SELECTIVE ELEMENT
Authors: Ahmad Fauzan , Nor Roslan Md , Harun Sulaiman Wadi , Ibrahim Mohd Haniff , Zalehan Mohamed , Ahmad Harith
Published: June 2024

We report a tunable wavelength fiber laser in Q switched regime using a droplet of single walled carbon nanotubes polymer composite as passive saturable absorber and array waveguide grating as wavelength selective element. The tuneable wavelength is around 18 nm and the repetition rate is fluctuated from 5.4 kHz to 15 kHz. The highest average output power is around 0.007 mW, the maximum pulse energy is 0.7 nJ and the minimum pulse width generated in this proposed set up is around 8 µs.
The Impact of Employee Commitment, Satisfaction, Recognition and Reward, Organizational Justice, and Employee Engagement in the Manufacturing Industry
Authors: Ahmad Zawawi Azlyn , Noorshuhaimi Muhammad Syamil , Harun Norfazwani Idayu
Published: June 2024

Employee engagement holds significant power in boosting productivity and propelling organizational success. This study examines the Malaysian manufacturing industry by investigating the key drivers of employee engagement. We analyze the interconnectedness of five crucial organizational factors – commitment, satisfaction, recognition, reward, and organizational justice – with employee engagement levels. Our findings reveal a strong positive correlation between elevated engagement and enhanced employee experiences: deeper involvement, heightened motivation, and greater job and company satisfaction. Moreover, the study demonstrates that increased engagement translates into tangible benefits for organizations, leading to significantly improved productivity, superior work quality, reduced employee turnover, and ultimately, enhanced organizational performance. This research underscores the critical role of reciprocal engagement in the manufacturing landscape. Employers who prioritize fostering positive relationships with their employees, invest in their growth and development, and uphold fair practices stand to significantly enhance workforce engagement and reap the associated rewards of a thriving organization.
Competition-Based Learning in Science Camp to Stimulate Upper Secondary School Students’ Motivation in Learning STEM
Authors: Kairi Nurul Izni , Jamaludin Noraini , Mohd Ridzuan Nur Diyan
Published: June 2024

This paper introduces a study on the implementation of science, technology, engineering, and mathematics (STEM)-related modules in a science camp to stimulate the interest and motivation of students in learning STEM. The study shows the decision taken by a student to pursue STEM in Tertiary education can be influenced by the people around them and the exposure provided during the high school years. The implementation of robust STEM education would help to combat the change at the age where students will seek their future direction. The incorporation of competition-based learning and experiential learning, combined with the other classical and active learning techniques, have motivated the students and indirectly sparked their interest in STEM. Five unique STEM-related modules have been incorporated into this 3-day and 2-night science camp, which consists of 72 upper-secondary school students from seven selected boarding schools around Malaysia. The purpose of the science camp is to provide exposure for the students to understand the significance of STEM, cultivate a culture of innovation, and indirectly boost motivation among the students. The experience gained is summarized from the analysis of the survey via qualitative and quantitative means. Positive survey results, where 96% are now pursuing their tertiary education in the field of STEM, suggest that students are directly influenced and motivated by the use of competition in the STEM modules to collaboratively appreciate the beauty of STEM education while learning it together with a mission to win the competition.