Effect of Proportion of Missing Data on Application of Data Imputation in Pavement Management Systems

Missing data are commonly found in pavement condition/performance databases. A common practice today is to apply statistical imputation methods to replace the missing data with imputed values. It is thus important for pavement management decision makers to know the uncertainty and errors involved in the use of datasets with imputed values in their analysis. An equally important information of practical significance is the maximum allowable proportion of missing data (i.e. level of data missingness in the pavement condition/performance records) that will still produce results with acceptable magnitude of error or risk when using imputed data. This paper proposes a procedure for determining such useful information. A numerical example analyzing pavement roughness data is presented to demonstrate the procedure through evaluating the error and reliability characteristics of imputed data. The roughness data of three road sections were obtained from the LTPP database. From these data records, datasets with different proportions of missing data were randomly generated to study the effect of level of data missingness. The analysis shows that the errors of imputed data increased with the level of data missingness, and their magnitudes are significantly affected by the effect of pavement rehabilitation. On the application of data imputation in PMS, the study suggests that at 95% confidence level, 25% of missing data appears to be a reasonable allowable maximum limit for analyzing pavement roughness time series data not involving rehabilitation within the analysis period. When pavement rehabilitation occurs within the analysis period, the maximum proportion of imputed data should be limited to 15%

Isoprene oxidation by the gram-negative model bacterium variovorax sp. WS11

Plant-produced isoprene (2-methyl-1,3-butadiene) represents a significant portion of global volatile organic compound production, equaled only by methane. A metabolic pathway for the degradation of isoprene was first described for the Gram-positive bacterium Rhodococcus sp. AD45, and an alternative model organism has yet to be characterised. Here, we report the characterisation of a novel Gram-negative isoprene-degrading bacterium, Variovorax sp. WS11. Isoprene metabolism in this bacterium involves a plasmid-encoded iso metabolic gene cluster which differs from that found in Rhodococcus sp. AD45 in terms of organisation and regulation. Expression of iso metabolic genes is significantly upregulated by both isoprene and epoxyisoprene. The enzyme responsible for the initial oxidation of isoprene, isoprene monooxygenase, oxidises a wide range of alkene substrates in a manner which is strongly influenced by the presence of alkyl side-chains and differs from other well-characterised soluble diiron monooxygenases according to its response to alkyne inhibitors. This study presents Variovorax sp. WS11 as both a comparative and contrasting model organism for the study of isoprene metabolism in bacteria, aiding our understanding of the conservation of this biochemical pathway across diverse ecological niches

ANALISA KINERJA TURBOCHARGER NA358 PADA MESIN GAS WARTSILA DI UNIT PEMBANGKITAN ARUN DENGAN KAPASITAS 184 MW

Pembangkit Listrik Tenaga Mesin Gas (PLTMG) merupakan representatif teknologi yangsedang berkembang pesat untuk memenuhi kebutuhan listrik. Dalam PLTMG, terdapatturbocharger yang berperan dalam meningkatkan proses pembakaran dan daya mesin dengankapasitas silinder yang sama. Tujuan penelitian ini untuk menganalisa kinerja turbochagerbank A dan bank B pada saat beban maksimum. Metode analisa yang digunakan denganaplikasi Wartsila Operator Interface System (WOIS). Analisa ini dilakukan untuk memitigasidampak kondisi abnormal pada efisiensi mesin. Oleh karena itu, analisa dan penangananpermasalahan turbocharger sangat penting untuk memastikan kinerja mesin yang optimal danmencegah kerusakan yang lebih besar pada sistem pembangkit daya. Hasil analisa kinerjamenunjukkan distribusi hubungan daya aktual dan ideal terhadap efisiensi isentropicturbocharger pada bank A. Daya aktual tertinggi adalah 3682,59 kJ/kg dengan efisiensi 89%,sementara daya ideal tertinggi adalah 3356,84 kJ/kg dengan efisiensi 90%. Pada bank B, dayaaktual tertinggi adalah 3695,50 kJ/kg dengan efisiensi 89%, sedangkan daya ideal tertinggiadalah 3356,84 kJ/kg dengan efisiensi 91%. Generator menghasilkan output daya aktif sebesar8824 kW dan hasil keluaran daya reaktif mencapai 12163 kVA. Generator beroperasi padafrekuensi 50 Hz dan faktor daya sebesar 0,8, dengan tingkat efisiensi sekitar 90%

Experimental investigation on hardness, tensile strength, and microstructure of Al-3,1Cu cast-alloy after T6-tempered

This research aims to investigate Brinell hardness and tensile strength properties of Al-3,1Cu cast-alloy after T6- tempered treatment and evaluate its microstructural changes. This experiment was first performed by using an electric furnace to melt the metal alloy. The liquid metal was then poured into a rectangular metal mold, and the properties of the cast sample material were improved by using T6 heat treatment. Furthermore, the cast product was processed following acceptable tensile and impact tests standards. The results showed an increase in Brinell hardness and tensile strength after T6-Tempered treatment on the cast product. The observation of the microstructure also showed that the precipitate that grows evenly in α was finely dotted

Impact toughness of ASTM A36 low carbon steel by metal active gas (MAG) welding process using different cooling media

This study was conducted to examine the immersion effect of cooling media used after the MAG welding process on impact toughness behavior of A36 steel plate. The media used in the experiment include air, water, and ice while CO2 shielding gas and ER70S-6 filler metal were used in the MAG process. It is also important to note that the speed of the weld material cooling process has the ability to affect the hardness and toughness of the post-welding product. The experimental results showed that the use of cooling media affected the impact properties of the welding joint. The highest toughness value was recorded in the ice cooling media with 4,38 J/mm2

Impact toughness of ASTM A36 low carbon steel by metal active gas (MAG) welding process using different cooling media

This study was conducted to examine the immersion effect of cooling media used after the MAG welding process on impact toughness behavior of A36 steel plate. The media used in the experiment include air, water, and ice while CO2 shielding gas and ER70S-6 filler metal were used in the MAG process. It is also important to note that the speed of the weld material cooling process has the ability to affect the hardness and toughness of the post-welding product. The experimental results showed that the use of cooling media affected the impact properties of the welding joint. The highest toughness value was recorded in the ice cooling media with 4,38 J/mm2

Analisis Kesesuaian Parameter Perairan terhadap Komoditas Tambak Menggunakan Sistem Informasi Geografis (Sig) di Kabupaten Pidie Jaya

The study aimed to determine the suitability of fishponds in Pidie Jaya, the research was done using GIS spatial analysis method, where the water parameter samples were collected from 20 sampling points, the samples were taken within the river or flow water beside the fishpond. There were 5 parameters measured included salinity, pH, dissolved oxygen, water visibility, and nitrate contents. The analysis was done using kriging interpolation, reclassification, and overlay analysis using weighted overlay. Analysis based on 4 suitability criteria, very suitable, suitable, less suitable, and not suitable. The results of this analysis are that the fishponds fall into very suitable and suitable criteria. Of the total of ±1842 Ha fishponds, 2.37% covering ±43.76 Ha is classified as very suitable, and 97.63% covering ±1798.23 Ha classified as suitable. Results show that Pidie Jaya is good choice for low cost aquaculture ponds with a little treatment for nitrates. Key words: Pidie Jaya; fishpond; GIS; suitability analysis; weighted overlay. Penelitian ini bertujuan untuk mengetahui kesesuaian lahan tambak berdasarkan kualitas perairan di pesisir Kabupaten Pidie Jaya. Penelitian ini dilaksanakan dengan menggunakan metode analisis spasial Sistem Informasi Geografis (SIG), sampel parameter perairan dikumpulkan dari 20 titik sampling pada saluran tambak. Parameter perairan yang diukur meliputi 5 parameter kunci yang sangat berpengaruh terhadap komoditas tambak, meliputi salinitas, pH, oksigen terlarut, kecerahan air dan kandungan nitrat. Langkah analisis dilakukan menggunakan ordinary kriging, reclassify, dan weighted overlay. Tingkat kesesuaian lahan dibagi kedalam 4 kelas, yaitu sangat sesuai, sesuai, kurang sesuai, dan tidak sesuai. Didapatkan 2 tingkat kesesuaian yaitu kelas sangat sesuai sebesar 2.37% (±43.76 Ha) dan kelas sesuai sebesar 97.63% (±1798.23 Ha) dari total keseluruhan luas tambak seluas ±1842 ha. Hasil tersebut menunjukkan bahwa tambak di Kabupaten Pidie Jaya sesuai untuk USAha pertambakan dengan sedikit perlakuan terhadap nitrat

Financial Stability of Islamic Versus Conventional Banks in Pakistan

This study aims to analyze and compare the financial stability of Pakistani banks covering a timeframe of 5 years from 2012 to 2016. This study employs the financial soundness indicators of the International Monetary Funds and State Bank of Pakistan and the z-score index. The comparative analysis through average scores is performed using 3 indicators of financial stability namely Z-Score, Capital Adequacy Ratio (CAR) and Equity to Total Assets Ratio. The findings of the research reveal that (i) conventional banks are more financially stable than Islamic banks; (ii) large conventional banks are more financially stable than large Islamic banks; (iii) small Islamic banks are less stable than small conventional bank. The implication of this paper is that conventional banks have the potential of absorbing financial stability shock as compare to Islamic banks on the basis of stated financial soundness indicators and Z-Score specifically.DOI: 10.15408/aiq.v10i2.650

Mechanical Properties of Carbon/Polypropylene Fiber Reinforced Rubber-Modified Epoxy System

Epoxies as a thermoset polymer have gained a considerable attention in structural, electrical, and marine applications. To widen their usage and overcome their brittleness, many polymers were blended with it. The addition of Polysulfide rubber helps in increasing the impact resistance of Epoxy, while in the other hand; it reduces strength , modulus, hardness and creep resistance. That leads to the need for another material to compensate the reduction in these properties. Carbon, polypropylene as an inorganic and polymeric short fibers with their exceptional and different mechanical properties will compensate many drawbacks of polysulfide addition in enhancing mechanical properties. The composite material with Epoxy-Polysulfide matrix properties were evaluated by conducting the mechanical tests which include compression test, hardness test, impact resistance test. The fracture surface of composite impact specimens was observed by Scanning Electron Microscopy SEM on all designed experimental samples. Elongation and impact strength of epoxy- polysulfide blend were found to increase with increasing rubber content while compressive strength and modulus decrease. The influence of fiber adding on the mechanical properties of the composite was studied , the mechanical properties of the blend matrix were found to be better than those of the pure epoxy. The morphology of the fractured surfaces showed significant signs of plastic deformation such as shear bands, high deformation, and cavitations due to rubber addition, and this correlates well with mechanical properties which resulted in an increase in toughness of the composites when rubber content was increased. The results of this investigation clearly show the possibility of balancing strength and toughness of the material when adding rubber, fiber to epoxy. Results of compression test showed that the compressive strength decreases as Polysulfide percentage (PS) increase. While the carbon fiber addition helped in balance or overcomes the original compressive strength reduction up to 30 vol.%. of fiber. The results confirmed that the best modification is the addition of 6% polysulfide considering compressive strength, Impact and hardness. While 20% carbon fiber and 30% Polypropylene fiber gives the optimum mechanical properties in compression and Impact, respectively, for the composite samples. Keywords: Epoxy resin, Liquid rubber, Mechanical properties