Judul: The Function and Role of The Hull Cell in Electroplating
Abstrak: Komposisi dan kondisi yang tidak sesuai pada suatu proses elektroplating dapat mengakibatkan berbagai masalah pada produk yang dihasilkan. Salah satu metode pengujian yang banyak digunakan dalam proses elektroplating ialah sel Hull yang dapat menyediakan fasilitas dasar dalam kontrol proses. Karya tulis ini bertujuan mengkaji secara ilmiah fungsi dan peranan sel Hull dalam elektroplating meliputi perkembangan, kinerja, dan aplikasi sel Hull. Karya tulis ini menggunakan metode kualitatif yang terdiri atas jenis kajian kepustakaan dengan tinjauan sistematis dan penelitian kualitatif deskriptif. Hasil penelitian menunjukkan bahwasanya tipe sel Hull elektrode-berputar merupakan pengembangan tipe sel Hull yang menyediakan kinerja terbaik untuk pengujian proses elektroplating. Kinerja sel Hull dipengaruhi oleh beberapa hal, yakni komponen yang digunakan, proses percobaan, dan interpretasi hasil deposit logam yang didapatkan. Contoh aplikasi sel Hull ialah untuk menentukan komposisi larutan plating yang optimum serta jenis aditif terbaik yang digunakan dalam proses plating logam nikel., Incorrect composition and conditions in an electroplating process can cause various problems in the resulting product. One of the most widely used test methods in the electroplating process is the Hull cell which can provide basic facilities for controlling the process. This paper aims to scientifically examine the function and role of the Hull cell in electroplating, including the development, performance, and applications of the Hull cell. This paper uses a qualitative method consisting of library research with a systematic review and descriptive qualitative research. The results showed that the developed rotating electrode Hull cell type provides the best performance for testing the electroplating process. The performance of the Hull cell is affected by several factors, namely the components used, the experimental process, and the interpretation of the metal deposit results obtained. An example of the application of the Hull cell is to determine the optimum composition of the plating solution and the best type of additive used in the nickel-metal plating process.
Keyword: corrosion, electroplating, Hull cell, nickel plating

Judul: Modifikasi Pelapisan Seng pada Baja dengan Chromating Trivalent menggunakan Bahan Organik Pereduksi
Abstrak: Baja merupakan logam yang banyak digunakan dalam industri perakitan dan konstruksi. Pelapisan seng pada baja diperlukan untuk memenuhi sifat fisik tahan korosi dan ketebalan yang sesuai kebutuhan industri. Perlakuan chromating pada proses pelapisan yang menggunakan kromium heksavalen dapat bersifat toksik sehingga harus direduksi menjadi kromium trivalen menggunakan bahan organik pereduksi. Penelitian ini bertujuan mengetahui pengaruh konsentrasi dan waktu pencelupan pada tahapan chromating terhadap laju korosi dan ketebalan lapisan seng pada baja. Penelitian dilakukan dalam larutan kromium dengan variasi konsentrasi 5; 10; 15 mL/L serta variasi waktu 10 dan 60 detik. Larutan kromium dibuat dari beberapa jenis sumber kromium yang berbeda, yaitu H2CrO4, Na2CrO4, K2Cr2O7. Ketebalan baja diukur dengan mikrometer sekrup digital dan pengukuran laju korosi menggunakan metode kehilangan berat. Hasil modifikasi terbaik ditunjukkan oleh spesimen yang dicelupkan pada larutan kromium trivalen 15 mL/L dari K2Cr2O7 dengan waktu 60 detik. Ketebalan yang dihasilkan adalah 0,0025 mm dengan laju korosi 0,0063 mm/tahun., Steel is a metal that is widely used in the manufacturing and construction industries. Zinc coating on steel is required to fulfill the physical properties of corrosion resistance and thickness suitable for industrial needs. The chromating treatment in the coating process using hexavalent chromium can be toxic, therefore it must be reduced to trivalent chromium by using reducing organic matter to avoid the negative impact. This study aims to determine the effect of concentration and immersion time in the chromating stage on the corrosion rate and the thickness of the zinc layer on the steel. This research was conducted in a chromium solution with concentration variation of 5; 10; 15 mL/L and time variations of 10 and 60 seconds. There are several chromium sources that used in this research, i.e H2CrO4, Na2CrO4, and K2Cr2O7. Thickness was measured with a digital screw micrometer and corrosion rate was measured using the weight loss method. The best modification results were shown by a specimen that was dipped in a 15 mL/L trivalent chromium solution of K2Cr2O7 for a time of 60 seconds. The resulting thickness is 0,0025 mm with a corrosion rate of 0,0063 mm/year.
Keyword: chromating, corrosion, steel, trivalent chrome, zinc plating

Judul: Utilization of terra/MODIS L1B data for analysis of horizontal wind profile in the troposphere
Abstrak: This study was concerned with horizontal wind derived from data collected with the Moderate-resolution Imaging Spectroradiometer (MODIS) on board the NASA’s Earth Observation System (EOS)-Terra satellite. The aim of this study is to develop a method for the estimation of horizontal wind movement in the troposphere based on Navier-Stokes equation. The method was applied to a calibrated and geolocated Terra/MODIS L1B 1 km data set. The data inputs to estimate surface temperature are retrieved from TIR (Thermal Infrared) bands 31 (10.780 μm to 11.280 μm) and 32 (11.770 μm to 12.270 μm). The obtained surface temperatures were later used to approximate geopotential height on a constant-pressure surface by using the modified Poisson equation. The main assumptions used are the hydrostatic equilibrium, ideal gas law, constant lapse rate and constant acceleration of gravity. Based on the distribution of geopotential height, the pressure gradient force is measured by the gradient of geopotential on an isobaric coordinate to present the horizontal wind profile. For certain topographic areas especially in the mountain ranges, there was a disadvantage of using pressure as a vertical coordinate which lead to inaccuracy. In spite of that, Terra/MODIS L1B data with 1 km spatial resolution can be used to estimate the horizontal wind movement in the troposphere.
Keyword: