Studi Eksperimental Pengaruh Model Sistem Saluran dan Variasi Temperatur Tuang terhadap Prosentase Porositas, Kekerasan dan Harga Impact pada Pengecoran Adc 12 dengan Metode Lost Foam Casting

Metode pengecoran lost foam merupakan metode yang tergolong baru dalam industri pengecoran logam. Pada saat ini belum banyak industri pengecoran logam yang menggunakan metode ini dalam memproduksi benda cor. Sedikitnya industri yang menerapkan metode pengecoran ini, yang mendorong untuk melakukan percobaan pengecoran dengan menggunakan metode lost foam, dengan melakukan perbedaan variasi temperatur tuang dan variasi model sistem saluran. Proses pengecoran dengan metode lost foam ini menggunakan styrofoam sebagai polanya, yang ditanam dalam cetakan yang berisi pasir silika kering (tanpa pengikat) kemudian cetakan digetarkan untuk memadatkan pasir. Ketika logam cair dimasukkan ke dalam cetakan, maka styrofoam akan menguap sampai cetakan tersebut terisi penuh oleh logam cair. Dalam penelitian ini, parameter yang digunakan adalah model sistem saluran dan variasi temperatur tuang terhadap kualitas hasil coran, diantaranya kekerasan, harga impact, prosentase porositas dan struktur mikro. Material yang digunakan dalam pengecoran ini adalah ADC (Aluminium Die Casting) 12. Parameter pertama yaitu model sistem saluran meliputi saluran samping, saluran bawah, saluran bawah dengan 2 gate dan saluran bawah dengan 3 gate dengan temperatur tuang konstan 700°C. Parameter kedua yaitu variasi perbedaan temperatur tuang antara 700°C, 750°C, 800°C dan 850°C dengan sistem saluran samping. Dari hasil penelitian ini diperoleh bahwa sistem saluran samping memiliki prosentase cacat porositas paling sedikit dibanding sistem saluran lainnya yaitu sebesar 2,7535% dan memiliki harga impact rata-rata paling besar yaitu 0,0275 J/mm2 pada potongan 1 dan 0,0660 J/mm2 pada potongan 2. Variasi temperatur tuang berpengaruh terhadap banyaknya cacat porositas dan harga impact rata-rata. Temperatur tuang 700°C dibanding temperatur tuang yang lain memiliki cacat porositas paling sedikit dan harga impact rata-rata paling besar yaitu 0,0275 J/mm2 pada potongan 1 dan 0,0660 J/mm2 pada potongan 2. Namun dari hasil pengujian kekerasan baik pada parameter model sistem saluran dan variasi temperatur tuang tidak dapat menunjukan perbedaan yang jelas

Protein Conformantional Search Using Bees Algorithm

Proteins perform many biological functions in the human body. The structure of the protein determines its function. In order to predict the protein structure computationally, protein must be represented in a proper representation. To this end, an energy function is used to calculate its energy and a conformational search algorithm is used to search the conformational search space to find the lowest free energy corformation

Evaluation of adipose tissue volume quantification with IDEAL fat-water separation

Purpose: To validate iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) for adipose tissue volume quantification. IDEAL allows MRI images to be produced only from adipose-containing tissues; hence, quantifying adipose tissue should be simpler and more accurate than with current methods. Materials and Methods: Ten healthy controls were imaged with 1.5 Tesla (T) Spin Echo (SE), 3.0T T1-weighted spoiled gradient echo (SPGR), and 3.0T IDEAL-SPGR. Images were acquired from the abdomen, pelvis, mid-thigh, and mid-calf. Mean subcutaneous and visceral adipose tissue volumes were compared between the three acquisitions for each subject. Results: There were no significant differences (P \u3e 0.05) between the three acquisitions for subcutaneous adipose tissue volumes. However, there was a significant difference (P = 0.0002) for visceral adipose tissue volumes in the abdomen. Post hoc analysis showed significantly lower visceral adipose tissue volumes measured by IDEAL versus 1.5T (P \u3c 0.0001) and 3.0T SPGR (P \u3c 0.002). The lower volumes given by IDEAL are due to its ability to differentiate true visceral adipose tissue from other bright structures like blood vessels and bowel content that are mistaken for adipose tissue in non-fat suppressed images. Conclusion: IDEAL measurements of adipose tissue are equivalent to established 1.5T measurement techniques for subcutaneous depots and have improved accuracy for visceral depots, which are more metabolically relevant. © 2011 Wiley-Liss, Inc

Effect of dehydration on the pharmacokinetics of oxytetracycline hydrochloride administered intravenously in goats (Capra hircus)

1. The effects of various levels of dehydration induced by water deprivation were studied in six Nubian goats on the pharmacokinetics of oxytetracycline after intravenous administration (5 mg/kg). 2. In goats that had lost an average of 7.6% body weight after 2 days of water deprivation, the elimination rate constant of the drug was significantly decreased (P<0.01) and the total body clearance was significantly slower (P<0.001). No statistically significant changes were observed in the pharmacokinetic parameters describing the distribution of the drug at this dehydration level. 3. Water deprivation for 3 or 4 days resulted in a level of dehydration at which the goats lost an average of 10.3% or 12.7% of their body weight, respectively; significant changes were observed in the pharmacokinetic distribution and elimination parameters of oxytetracycline. The volume of distribution at steady state was significantly decreased (P<0.01). Significantly slower total body clearance (P<0.001) and subsequent prolongation of the elimination half-life were found at these dehydration levels. 4. The alterations caused by dehydration on the disposition kinetics of the drug should be considered for better definition of dosage regimens for sick, dehydrated animals

Integration of global positioning system and inertial navigation system with different sampling rate using adaptive neuro fuzzy inference system

Integration of the Global Positioning System (GPS) and Inertial Navigation System (INS) has become increasingly common in the last two decades, because the characteristics of GPS and INS are complementary and the integration between both systems will maximize their advantages and minimize their weakness. Over time, inertial navigators drift from their preset alignments. Or, the initial alignment may have been corrupted by vehicle motion, with imperfect transfer of alignment and velocities to the navigator. Also, there may not have been enough time to perfect alignment. In such case, navigators can be benefit from aiding such as GPS. The integration between the GPS and INS leads to accurate navigation solution by overcoming each of their respective shortcomings. And to make this integration possible the difference between the GPS and INS systems in sampling rate must be solved before any integration can be work properly. In this paper, the GPS low rate problem is solved by predicting or extrapolating the mislaid reading data of the GPS to be attuned with those of INS data using Adaptive Neuro Fuzzy Inference System (ANFIS). Hence, the gap between the two systems reading data is solved to provide synchronization between the INS and GPS systems. So, it is possible to compare the reading data of both systems. Three strategies have been proposed and the results shows superior performance in predicting missed GPS data with lowest mean error

Pharmacokinetics of ampicillin trihydrate following intravenous administration to water deprived Nubian goats

The present study reports the effect of water deprivation in the Nubian goat on the pharmacokinetics of ampicillin trihydrate following intravenous administration at a dose rate of 10 mg kg-1. Water deprivation for two days, which resulted in about 7.5 per cent loss in bodyweight, produced no significant effects on the pharmacokinetic parameters of the drug. In dehydrated goats that had lost an average of 9.8 per cent of their initial bodyweights, within three days of water deprivation, ampicillin showed significantly slower clearance values (P < 0.001), without affecting significantly the pharmacokinetic parameters describing the distribution of the drug. After four days of water deprivation a dehydration level at which goats lost an average of 12.6 per cent bodyweight was reached, which resulted in significant alterations in the distribution and elimination pharmacokinetic parameters of ampicillin. The volume of the central compartment (Vc) and the volume of distribution at steady state (Vdss) were significantly decreased (P < 0.01) leading to significant elevation in plasma concentrations of the drug (P < 0.01) compared with the normally hydrated animals. In water deprived goats, significantly slower clearance of the drug (P < 0.001) and reduced elimination rate constant (P < 0.01) with the subsequent increases in the half-life time were also observed. Dosage intervals between the usual doses of ampicillin can be increased in dehydrated goats and concentrations which were high enough to kill susceptible microorganisms could still be achieved

Determining areas of improvement in quranic arabic vocabulary learning mobile applications through analysis of app user reviews

Muslims constitute roughly around one fifth of the world population, the majority of which are not Arabic speakers. This poses a problem for them in their devotional activities such as performing the five obligatory daily prayers and reading the Holy Qur’an because they could not understand what they are reciting or reading. Added to this, Muslim adults who are busy working usually find it hard to find the time to attend Quranic Arabic classes. In order to rectify this problem, some mobile app developers have created apps with the objective of teaching Muslims Quranic Arabic vocabulary items so that they could begin to learn and understand Quranic Arabic. In March 2019, there are about eleven Quranic Arabic vocabulary teaching mobile applications which could be downloaded from Google Play Store. These apps come with differing features and are of varying quality. This exploratory qualitative study aims to analyze the user reviews of these apps in order to determine areas where they can be further improved by the developers. The findings of this research found that generally developers should concentrate on three areas of improvement; their applications’ content, technical capability, and pricing strategy. It is hoped that the findings from this study can be used by Quranic Arabic vocabulary mobile app developers to further improve their apps so that the Muslim public can benefit more from them

The perception of Iraqi EFL learners towards the use of MALL applications for speaking improvement

The current study is an attempt to understand the perceptions of Iraqi EFL learners about the use of Mobile Assisted Language Learning (MALL) applications for the purpose of speaking skills improvement. The respondents of the study are 51 EFL students enrolled in the Bachelor program in the department of English Language in the Faculty of Education for Humanities at Anbar University, Rammadi, Iraq. The respondents are chosen from different academic years. The data collection is carried out using a structured interview questions adopted form Son's (2016) study. However, the adopted interview survey is structured in the form of open questions rather than close questions (See Appendix A). The open interview questions give the respondents more freedom in clarifying their perceptions about the proposed MALL applications, whereby the researcher could collect rich information about the preferred characteristics of MALL applications for EFL students to improve their English speaking skills. The results of the study revealed that the respondents have a positive view and attitude towards using MALL applications for speaking improvement. The outcome of the study is advantageous for learners, teachers and language academies to highlight the importance of using MALL applications for language skills improvement and speaking skills in particular