95 research outputs found
Implementations of geographically weighted lasso in spatial data with multicollinearity (Case study: Poverty modeling of Java Island)
No full textModeling relationship between mean years of schooling and household expenditure at Central Sulawesi using constrained B-splines (COBS) in quantile regression
No full textSensitivity analysis and its role in expert judgment
No full textSensitivity analysis has become an essential tool for assessing the importance of inputs in
mathematical models or computer models. The models could be simple or complex and
might not be formulated transparently. Model input uncertainty is often quantified using
expert judgement, but obtaining or eliciting expert judgement can be time-consuming. It
may not be practical to elicit distributions for all inputs in the model, especially when the
number of inputs is large. Eliciting inputs that have a small effect on the output may not
be worth it.
In this thesis, we explore sensitivity analysis methods and develop criteria for establishing
when inputs are unimportant. We also study how to make elicitation for model inputs
efficient, by employing sensitivity analysis to select which inputs are a priority for elicitation. However, we find that ’standard’ application of sensitivity analysis for prioritising
elicitation may not give the right results. We propose a novel model for expert judgement
which we call the Beta Model. The Beta model is easy to implement compared with other
previous models for expert opinion. Sensitivity analysis is proposed on the parameters
of this model, and a grid-based computational method is proposed to compute suitable
sensitivity indices
Penentuan Sampling Minimal Dalam Eksperimen Life-Testing menggunakan Order Statistics
No full textAnalisis reliabilitas merupakan salah satu alat statistika yang digunakan untuk mengukur tingkat berfungsinya suatu alat/komponen. Suatu alat/komponen dikatakan reliabel jika masih berfungsi dengan baik dalam suatu jangka waktu tertentu. Selama ini proses pengukuran lifetime lampu pijar yang diproduksi PT Phillips Ralin Electronics Surabaya dilakukan sampai semua lampu yang diambil sebagai sampel mati, sehingga proses ini memerlukan waktu dan biaya yang cukup besar.
Salah satu cara yang bisa dilakukan untuk mengurangi waktu dan biaya dalam eksperimen life-testing adalah dengan menentukan sampling minimal dalam eksperimen life-testing lampu pijar yang bisa diperoleh berdasarkan urutan kerusakan yang terjadi. Sehingga proses pengukuran lifetime lampu pijar tidak perlu dilakukan sampai semua lampu yang diambil sebagai sampel mati. Hal ini bisa didapatkan dengan cara memperoleh momen order ke-k dari fungsi densitas order statistics yang sesuai dengan distribusi data waktu kerusakan dari lifetime lampu pijar.
Berdasarkan momen order ke-k dari fungsi densitas order statistics yang sesuai dengan distribusi waktu kerusakan Weibull, dapat diketahui sampling minimal yang dibutuhkan dalam eksperimen life-testing lampu pijar berdasarkan spesifikasi lampu 220V/40W/A60/CL/E27 adalah 18 (urutan kerusakan ke-18 dari 26 sampel lampu). Sehingga penghematan yang bisa dilakukan adalah sebesar 39,3 %.
Kata Kunci: Distribusi weibull, Fungsi hazard rate, Order statistics, Reliabilitas
OPTIMASI KARAKTERISTIK KUALITAS LEAD-SLAG PERISAI RADIASI BETON MENGGUNAKAN METODE GREY-TAGUCHI DESIRABILITY FUNCTION
No full textAbstrak
Perisai radiasi yang digunakan untuk melindungi dari bahaya radiasi merupakan salah satu masalah penting dalam bidang fisika nuklir. Beton merupakan bahan yang efektif, fleksibel dan ekonomis digunakan untuk perisai radiasi. Dalam perisai radiasi beton, berbagai macam bahan dapat digunakan untuk melemahkan foton. Lead-slag perisai beton yang digunakan dalam aplikasi nuklir selain melindungi property harus memiliki karakteristik kualitas yang optimal. Tujuan dari penelitian ini adalah mendapatkan komposisi faktor pembentukan perisai radiasi beton sehingga didapatkan kualitas perisai radiasi beton yang optimal. Metode grey-taguchi desirability function digunakan dengan mempertimbangkan beberapa karakteristik kualitas yang diukur secara simultan. Hasil optimasi didapatkan pada faktor perbandingan air -semen 0,42, kandungan semen 390 kg/m3, perbandingan volume lead-slag agregat 60% dan perbandingan silica-semen 0,15.
Kata-kata kunci: optimasi, grey-taguchi desirability function, lead-slag perisai radiasi beton
Abstract
Radiation shields are used to protect from the harmful effects of radiation is one of the important problems in the field of nuclear physics. Concrete is a material that is effective, flexible and economically used for radiation shielding. In concrete radiation shielding, a variety of materials can be used to attenuate photons. Lead-slag concrete shielding used in nuclear applications in addition to protecting the property must have the characteristics of optimal quality. The purpose of this research is to get the composition of the factors formation of radiation shielding concrete to obtain quality concrete optimal radiation shield. Grey-Taguchi method desirability function is used by considering some quality characteristics measured simultaneous. The results obtained in the optimization factor water-cement ratio of 0.42, cement content of 390 kg/m3, volume fraction lead-slag aggregate of 60% and silica fume-cement ratio of 0.15.
Keywords: optimizaion, grey-taguchi desirability function, lead-slag radiation shielding concrete
The Determination of Preventive Maintenance using Simulated Annealing Algorithm based on Weighted Fitness Function
No full textThis study aims to determine the machine maintenance schedule. We use the Simulated Annealing Algorithm. Fitness and reliability functions are functions that are used in the optimization process. Several weighting scenarios are done to see the unity of the function. The results of the scenario produce several alternative schedules. This algorithm is implemented on machines that have more than one sub-machine. This sub-machine is a smaller engine system part. This sub-machine also has one particular function. The results of the study show that the optimal engine maintenance period to use is six periods. There are five scheduling scenarios used in this problem. The resulting schedule can increase the value of reliability and can minimize costs
Penggunaan media electronic commerce dalam meningkatkan efisiensi waktu proses pembelian di industri automotive
No full textPenggunaan media electronic commerce dalam meningkatkan efisiensi waktu proses pembelian di industri automotiv
Jadwal Preventive Maintainance Mesin Menggunakan Algoritma Genetik Steady State Dengan Fungsi Kecocokan Berbasis Required Reliability
No full textPreventive maintainance activities are very important for manufacturing industries in order to maintain lifetime of their components/machines and to improve their performances. This research determines preventive maintainance schedules which minimize total cost and maximize reliability of components/machines. Some methods are already developed to obtain the schedule, exact method for example, has been used for many years. However this method having a drawback in the optimization process, in particular is model complexity, time consuming, and may lead to produce unfeasible solutions. Therefore, to overcome the problems, this research use another possible method namely Steady State Genetic Algorithm (SSGA). This research uses fitness function that is depend on Required Reliability which is stated by the company.In this research, SSGA is used to solve the problem of optimizationing in determining preventive maintainace schedule. This method was implemented to determine preventive maintainace schedule of Freeze Drying belongs to Pindad Cooperation. In this case, SSGA involed population size of 2,000 becauseit produces small variance solution and genetic cycle of 500 which produce convergent values based both on cost and reliability. According to the schedule, if the manufacturer would like to obtain machine reliability of60%, then there are not any maintaince avctivites requred during the period of 15 months. In addition, ifthe reliabilityof 80% required, then the company should perform replacement action on the first month and the tenth month. The company should alse perform maintainance activity on the fourth month with cost needed to do the actions is Rp 784,450. This schedule produces reliability for the machine of 68.71%
Jadwal Preventive Maintainance Mesin Menggunakan Algoritma Genetik Steady State Dengan Fungsi Kecocokan Berbasis Required Reliability
No full textPreventive maintainance activities are very important for manufacturing industries in order to maintain lifetime of their components/machines and to improve their performances. This research determines preventive maintainance schedules which minimize total cost and maximize reliability of components/machines. Some methods are already developed to obtain the schedule, exact method for example, has been used for many years. However this method having a drawback in the optimization process, in particular is model complexity, time consuming, and may lead to produce unfeasible solutions. Therefore, to overcome the problems, this research use another possible method namely Steady State Genetic Algorithm (SSGA). This research uses fitness function that is depend on Required Reliability which is stated by the company.In this research, SSGA is used to solve the problem of optimizationing in determining preventive maintainace schedule. This method was implemented to determine preventive maintainace schedule of Freeze Drying belongs to Pindad Cooperation. In this case, SSGA involed population size of 2,000 becauseit produces small variance solution and genetic cycle of 500 which produce convergent values based both on cost and reliability. According to the schedule, if the manufacturer would like to obtain machine reliability of60%, then there are not any maintaince avctivites requred during the period of 15 months. In addition, ifthe reliabilityof 80% required, then the company should perform replacement action on the first month and the tenth month. The company should alse perform maintainance activity on the fourth month with cost needed to do the actions is Rp 784,450. This schedule produces reliability for the machine of 68.71%
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