Production and Delivery Batch Scheduling with Multiple Due Dates to Minimize Total Cost

This paper addresses an integrated production and delivery batch scheduling problem for a make-to-order environment over daily time period, where the holding costs of in-process and completed parts at a supplier location and of completed parts at a manufacturer location are distinguished. All orders of parts with different due dates from the manufacturer arrive at the same time. The parts are produced in production batches and subsequently the completed parts are delivered in delivery batches using a capacitated vehicle in order to be received at the respective due dates. This study was aimed at finding an integrated schedule of production and delivery batches so as to meet the due date at minimum total cost consisting of the corresponding holding cost and delivery cost. The holding cost is a derivation of the so-called actual flow time (AFT), while the delivery cost is assumed to be proportional to the number of deliveries. The problems can be formulated as an integer non-linear programming model, and the global optimal solution can be obtained using optimization software. A heuristic algorithm is proposed to cope with the computational time problem using software. The numerical experiences show that the proposed algorithm yields near global optimal solutions

Usulan Sistem Pengendalian Persediaan Kelapa Studi Kasus: PT. Setia Tri Jujur Bersama Manado

Pengendalian persediaan adalah aktivitas dan teknik pengendalian persediaan barang baik bahan baku, barang setengah jadi ataupun barang jadi. Untuk membuat suatu sistem pengendalian persediaan pertama-tama penulis melakukan evaluasi persediaan kelapa tahun 2005 dengan melakukan penyesuaian kebutuhan kelapa sesuai dengan permintaan tepung kelapa. Kemudian penulis melakukan perhitungan persediaan dengan menggunakan model pemeriksaan kontinu (continuous review) dan pemeriksaan periodic (periodic review). Setelah itu dilakukan peramalan kebutuhan kelapa untuk tahun 2006. Setelah didapatkan jumlah kebutuhan kelapa tahun 2006, maka penulis melakukan perhitungan dengan model pemeriksaan kontinu dan pemeriksaan periodik kembali. Dalam perhitungan ini, seluruh biaya-biaya persediaan diasumsikan mengalami kenaikan sebesar inflasi yaitu 7.33%. Pada tahapan ini akan didapatkan model pengendalian persediaan yang tepat diterapkan di Perusahaan berdasarkan kategori biaya. Kata kunci: Pengendalian persediaan, model pemeriksaan kontinu (continuous review), model pemeriksaan periodik (periodic review), peramalan, total biaya persediaan, SOP. Absract Inventory controls are the activities and techniques of maintaining the stock of items at desire level, whether they are raw materials, work in process orfinished products. To make an inventory control system, firstly the writer evaluated thecoconut inventory in 2005 by doing some adjustment based on the desiccated coconut demand. Then the writer counted the inventory by using continues review and periodic review models. After that the demand of coconut on 2006 is forecasted. After the writer got the demand quantity of coconut on 2006, the writer recounted the inventory by using continuous review and periodic review models. In this calculation, the inventory costs are assumed to increase 7,33% (inflation rate in 2006). In this step, we will get the optimal inventory control model that suitable to be implemented in the company

Synthesis of NaY Zeolite Using Mixed Calcined Kaolins

Kaolin is one of several types of clay minerals. The most common crystalline phase constituting kaolin minerals is kaolinite, with the chemical composition Al2Si2O5(OH)4. Kaolin is mostly used for manufacturing traditional ceramics and also to synthesize zeolites or molecular sieves. The Si-O and Al-O structures in kaolin are inactive and inert, so activation by calcination is required. This work studies the conversion of kaolin originating from Bangka island in Indonesia into calcined kaolin phase as precursor in NaY zeolite synthesis. In the calcination process, the kaolinite undergoes phase transformations from metakaolin to mullite. The Bangka kaolin is 74.3% crystalline, predominantly composed of kaolinite, and 25.7% amorphous, with an SiO2/Al2O3 mass ratio of 1.64. Thermal characterization using simultaneous DSC/TGA identified an endothermic peak at 527°C and an exothermic peak at 1013°C. Thus, three calcination temperatures (700, 1013, and 1050 °C) were selected to produce calcined kaolins with different phase distributions. The best product, with 87.8% NaY zeolite in the 54.7% crystalline product and an SiO2/Al2O3 molar ratio of 5.35, was obtained through hydrothermal synthesis using mixed calcined kaolins with a composition of K700C : K1013C : K1050C = 10 : 85 : 5 in %-mass, with seed addition, at a temperature of 93 °Cand a reaction time of 15 hours

Designing multifunctional landscapes for forest conservation

A multifunctional landscape approach to forest protection has been advocated for tropical countries. Designing such landscapes necessitates that the role of different land uses in protecting forest be evaluated, along with the spatial interactions between land uses. However, such evaluations have been hindered by a lack of suitable analysis methodologies and data with fine spatial resolution over long time periods. We demonstrate the utility of a matching method with multiple categories to evaluate the role of alternative land uses in protecting forest. We also assessed the impact of land use change trajectories on the rate of deforestation. We employed data from Kalimantan (Indonesian Borneo) at three different time periods during 2000–2012 to illustrate our approach. Four single land uses (protected areas (PA), natural forest logging concessions (LC), timber plantation concessions (TC) and oil-palm plantation concessions (OC)) and two mixed land uses (mixed concessions and the overlap between concessions and PA) were assessed. The rate of deforestation was found to be lowest for PA, followed by LC. Deforestation rates for all land uses tended to be highest for locations that share the characteristics of areas in which TC or OC are located (e.g. degraded areas), suggesting that these areas are inherently more susceptible to deforestation due to foregone opportunities. Our approach provides important insights into how multifunctional landscapes can be designed to enhance the protection of biodiversity

On the Analysis of Trajectory-Based Search Algorithms: When is it Beneficial to Reject Improvements?

We investigate popular trajectory-based algorithms inspired by biology and physics to answer a question of general significance: when is it beneficial to reject improvements? A distinguishing factor of SSWM (strong selection weak mutation), a popular model from population genetics, compared to the Metropolis algorithm (MA), is that the former can reject improvements, while the latter always accepts them. We investigate when one strategy outperforms the other. Since we prove that both algorithms converge to the same stationary distribution, we concentrate on identifying a class of functions inducing large mixing times, where the algorithms will outperform each other over a long period of time. The outcome of the analysis is the definition of a function where SSWM is efficient, while Metropolis requires at least exponential time. The identified function favours algorithms that prefer high quality improvements over smaller ones, revealing similarities in the optimisation strategies of SSWM and Metropolis respectively with best-improvement (BILS) and first-improvement (FILS) local search. We conclude the paper with a comparison of the performance of these algorithms and a (1, λ ) RLS on the identified function. The algorithm favours the steepest gradient with a probability that increases with the size of its offspring population. The results confirm that BILS excels and that the (1, λ ) RLS is efficient only for large enough population sizes

Aplikasi Model Perencanaan Pemotongan (Cut Order Planning) pada Industri Garment

Perencanaan pemotongan kain merupakan kegiatan penting pada suatu industri pakaian/garment, sebelum proses pemotongan dan proses manufaktur dilakukan. Masalah dalam perencanaan pemotongan kain pada industri garment adalah penempatan pola/pattern bagian-bagian pakaian pada selembar kain (bahan) yang dapat memaksimalkan luas areal kain yang terpakai dengan biaya pemotongan yang minimal. Perencanaan pemotongan bahan (cut order planning) merupakan masalah yang kompleks karena ukuran, style dan due date pakaian yang dipesan konsumen sangat bervariasi. Faktor maksimisasi luas areal kain yang terpakai dan minimisasi biaya pemotongan kain pada suatu industri garment, oleh karenanya penelitian yang melibatkan kedua faktor ini sangan diperlukan. Penelitian ini menggabungkan metode penempatan trim Grienda dan Daniels (1999) dengan metode minimisasi biaya pemotongan kain melalui kombinasi ukuran pola/pattern pada suatu seksi (Jacobs et al, 1998). Pengujian terhadap model yang dihasilkan dilakukan dengan menggunakan data real dari suatu industri garment di Bandung

Motivation to Share Knowledge of Doctors in Teaching Hospital in Indonesia

The development of medical science and information communication technology recently cannot be separated. Its means that the rapid flow of information and knowledge, facilitated by information and communication technologies, makes the rapid development of medicine field and become a mandatory for all actors to keep improving their skills in the form of both soft and hard skills. This condition is followed with serious challenges, that many doctors still have a reluctance to share information and knowledge to their colleagues, especially with regard to the unique and complex cases. The main objective of this research was to determine the factors that affect the motivation of a doctor in conducting knowledge sharing with peers, especially at 4 (four) teaching hospitals in Indonesia. This research used a direct survey method through computer-based questionnaire. The number of questionnaires were collected and further processed as many as 76 examples with a participation rate of 34.55% (from a total of 220 examples of questionnaires were distributed using surveymonkey.com). The results of processing and data analysis using PLS-SEM showed that variables that had a significant influence on the motivation of doctors to share knowledge are enjoyment helping others and rewards. The main conclusion of this study is that doctors who determines the motivation to share knowledge with colleagues is coming from personal motivation and is not due to the stimulus coming from the head of the hospital's management, although the results showed that in fact there has been rewards mechanisms of the management, but the impact has not been felt particularly to increased motivation in performing activities of a doctor voluntarily sharing knowledge to colleagues

Motivation to Share Knowledge of Doctors in Teaching Hospital in Indonesia

The development of medical science and information communication technology recently cannot be separated. Its means that the rapid flow of information and knowledge, facilitated by information and communication technologies, makes the rapid development of medicine field and become a mandatory for all actors to keep improving their skills in the form of both soft and hard skills. This condition is followed with serious challenges, that many doctors still have a reluctance to share information and knowledge to their colleagues, especially with regard to the unique and complex cases. The main objective of this research was to determine the factors that affect the motivation of a doctor in conducting knowledge sharing with peers, especially at 4 (four) teaching hospitals in Indonesia. This research used a direct survey method through computer-based questionnaire. The number of questionnaires were collected and further processed as many as 76 examples with a participation rate of 34.55% (from a total of 220 examples of questionnaires were distributed using surveymonkey.com). The results of processing and data analysis using PLS-SEM showed that variables that had a significant influence on the motivation of doctors to share knowledge are enjoyment helping others and rewards. The main conclusion of this study is that doctors who determines the motivation to share knowledge with colleagues is coming from personal motivation and is not due to the stimulus coming from the head of the hospital's management, although the results showed that in fact there has been rewards mechanisms of the management, but the impact has not been felt particularly to increased motivation in performing activities of a doctor voluntarily sharing knowledge to colleagues