Vertical Roller Mill (VRM) merupakan tipe baru peralatan grinding, yang mengkombinasikan berbagai fungsi proses dalam pengoperasiannya termasuk proses grinding, proses pengeringan, dan proses pemisahan, dan merupakan peralatan grinding yang memiliki efisisensi energi yang tinggi. Stabilitas pengendalian operasi dan kehalusan raw meal yang sesuai dengan kualitas merupakan factor penting untuk mendapatkan kondisi operasi normal pada VRM.
Penelitian ini bertujuan mendapatkan metode pemodelan bagi VRM untuk memprediksi residu 90 mikron dan residu 200 mikron dari produk raw meal menggunakan Back Propagation Neural Network (BPNN). Pembuatan model BPNN dapat dilakukan dalam beberapa langkah, yaitu persiapan data input, menentukan sturuktur BPNN, pemilihan optimizer dan loss function, dan pelatihan BPNN serta evaluasi model yang dibuat.
Normalisasi data merupakan bagian dari persiapan data input, yang mana metode ini mengubah nilai output kedalam nilai kisaran baru. Sedangkan untuk arsitektur model, pada penelitian ini BPNN dirancang dengan menggunakan 4 variabel dan 6 variabel pada lapisan masukan, 4 lapisan tersembunyi dengan 52 neuron untuk setiap lapisannya. Sedangkan lapisan keluaran memiliki 2 variabel keluaran.
Pada penelitian ini menggunakan 3 tipe optimizer untuk mengoptimalkan parameter loss function, yaitu Adagrad, Adam, dan RMSprop. Dari hasil evaluasi pada model, penggunaan RMSprop optimizer dan MSE sebagai loss function memberikan hasil yang lebih baik dalam memprediksi data kualitas residu produk VRM dibandingkan optimizer lainnya.
Vertical Roller Mill (VRM) is a new type of grinding equipment, which combines multiple functions that include grinding, drying, and separating, and is energy efficient grinding equipmen. Stability of the process control and suitable raw meal fineness are the key factors to determine the normal operation of the VRM.
This study proposes a method for modeling the VRM to predict residue 90 micron and residue 200 micron of the raw meal product using Back Propagation Neural Network (BPNN). Making a neural network model in BPNN can be done in a few steps. The modelling step is input preparation, BPNN structure determination, optimizer and loss function selection, training BPNN and model evaluation.
Normalization is part of input preparation. This method resets the feature or output to a range of new values. For structure architecture, BPNN Modeling VRM Raw Meal uses one input layer with 4 and 6 input variables, with 4 hidden layers with 52 neuron for each hidden layers. While the output consists of one layer with 2 target output variables.
In this research, the modeling using 3 optimizers to optimize parameter of loss function. The optimizers are Adagrad, Adam, and RMSprop. From model evaluation, RMSprop optimizer and MSE loss function show better modelling results than others to predict residue data quality of the VRM raw meal products.
"
Aseptic loosening and infection are the two major causes for premature orthopedic implant failure. One of the strategies to prevent both scenarios is by modifying surface of orthopedic implant. The surface should have minimum surface roughness with nano topography. Plasma electrolytic polishing is a finishing process known for its ability to provide highly smooth and glossy surface. The two variables are electrolyte composition and polishing time. Surface roughness is measured using surfcom roughness contouring detector and surface topography is observed using SEM. The result of surface roughness measurement shows lowest and highest surface roughness are at 0,0889 µm and 0,6281 µm. SEM observation shows crater-like nanostructure with pits and ridges with electrolyte comprised of H3PO4, NaClO4, and HF meanwhile nanotructures of pits on top of smooth surface is available with electrolyte comprised of ethylene glycol and NH4F and electrolyte comprised of NaCl. The increase of polishing time shows smoothing effects on orthopedic implant surfaces especially on 90 and 120 s. Increase in hardness of polished samples indicates the presence of oxide layer in the surface. Polished samples are free from remainder of electrolyte therefore preventing possibility of allergic reaction or contamination of substance that is toxic for the body."
