<p>Drilling operations always require fluid in their activities. Because to penetrate the soil and rocks will be very easy with the use of fluid.  The fluid will help soften the soil and rocks making it easier for the drill bit to penetrate it. Drilling fluid is also needed to attach the casing to the drill wall. So that the wall does not collapse, as media logging and so on. Of course, each drilling zone (surface zone, intermediate zone, and production zone) has different characteristics and different additive substances are needed. This study wants to find out the function of the use of calcium chloride additives on the nature of cement hardness and choking time. This research is important because it will be known this addictive nature as a retarder or accelerator. By knowing the nature of this additive so that it can be used in the right zone. Testing on Calcium Chloride additive for the value of compressive strength is very effective at a concentration of 8%, 24-hour immersion time and a temperature of 150 ° F with a test result of 4483 psi. Whereas, at temperatures of 80 ° F and 100 ° F, the maximum value of compressive strength for Calcium Chloride additive occurs at a concentration of 10% with a test result of 2393 psi and 2888 psi. Based on the data presented, temperature plays an important role in testing the thickening time of a cement sample. The addition of calcium chloride additive functions as an accelerator.</p>

<p>Studi ini bertujuan untuk mengetahui dampak fluktuasi harga minyak di pasar dunia terhadap harga minyak Indonesia melalui data runtun waktu dari harga rata-rata minyak dunia dan harga rata-rata minyak Indonesia. Melalui koefisien korelasi dalam ilmu statistik, data runtun waktu dari kedua variabel harga rata-rata minyak dunia dan harga rata-rata minyak Indonesia diperoleh nilai 0,91, harga ini mendekati nilai +1 yang berarti menunjukan hubungan yang kuat antara dua variabel yaitu harga rata-rata minyak dunia dengan harga rata-rata minyak Indonesia. Meningkatnya harga minyak Indonesia tentu akan berdampak buruk pada perekonomian dalam negeri, oleh karena itu perlu adanya perhatian pemerintah untuk menempuh langkah-langkah yang bisa mengubah kebiasaan masyarakat yang semula boros BBM menjadi hemat BBM. Selain itu, dibutuhkan pula kebijakan dalam mendorong pengembangan energi alternatif.</p><p><strong>Kata kunci: </strong>minyak, ekonomi, harga</p>

Textile materials, especially yarns formed from polymers such as polyester during deformation, have viscoelastic properties, namely a combination of elastic and viscous properties. Several studies have been conducted to model viscoelastic on textile materials, especially yarns. In this study, modelling is done by fitting data through experiments which are then modelled with a theory of the modification of the Maxwell model as a reference in making predictions through the data fitting method. The results of the data fitting prediction in the form of exponential curves have a regression value that approaches the experimental curve (R 2 = 0.999 and 0.999).

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Metal coatings are starting to be widely used as a way to prevent metals from corroding. In addition to preventing corrosion, metal coatings have been developed to thicken metals, increase hardness, wear resistance, and corrosion resistance. Characterization of the materials used using SEM, and XRD. The SEM characterization results show a crystal shape similar to a pyramid. The increasing coating time will increase the crystal size with the preferred plane orientation direction is [111] with the largest crystal size in the experiment with a time of 4.5 h which is 55.44 nm using the Williamson-Hall method.