The vendor location problem

Cataloged from PDF version of article.The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two versions of the problem with different objectives: maximizing the total profit and maximizing the demand covered. The demand and profit generated by a demand point are functions of the distance to the vendor. We propose integer programming models for both versions of the vendor location problem. We then prove that both are strongly NP-hard and we derive several families of valid inequalities to strengthen our formulations. We report the outcomes of a computational study where we investigate the effect of valid inequalities in reducing the duality gaps and the solution times for the vendor location problem

Seasonal changes on total fatty acid composition of carp (Cyprinus carpio L. ), in vriz Dam Lake, Turkey

The effects of seasonal variation on the fatty acid composition of carps Cyprinus carpio were determined. A total of 38 different fatty acids were determined in the composition of carps. There were quantitative differences between fatty acids in muscle tissue investigated, depending on the season. Oleic acid C18:1 9 was the major monounsaturated fatty acid (MUFA) in all seasons. Palmitic acid C16:0 was identified as the major saturated fatty acid (SFA) in four seasons. Palmitoleic acid C16:1 wasthe third highest fatty acid in total fatty acids. MUFAs were found to be higher than SFAs and polyunsaturated fatty acids (PUFAs) in all seasons. Docosahexaenoic acid C22:6 3, linoleic acid C18:2 6 and eicosapentaenoic acid C20:5 3 were the highest levels among the PUFAs. The percentages of 3 fatty acid were higher than those of total 6 fatty acid in the fatty acid composition of carp. In the present study, 3/6 ratios were found to be 1.08, 1.43, 1.64 and 1.60 in spring, summer, autumn and winter, respectively. C. carpio may be a valuable food for human consumption in terms of fatty acids

Kinematic synthesis of flight control systems for light aircrafts

In this paper, kinematic synthesis of a planar flight control system mechanism has been conducted for a light aircraft designed and built by TAL To achieve a simple construction, the four-bar linkages are used in the synthesis. Freudenstein's Method and Bloch's Method are utilized for analytical three and four bar position syntheses respectively. A case study of an elevator flight control system is presented

Determination of the seasonal changes on total fatty acid composition of rainbow trout, Oncorhynchus mykiss in Ivriz Dam Lake, Turkey

Total fatty acid compositions and seasonal variations of Oncorhynchus mykiss in Ivriz Dam Lake, Turkey were investigated using gas chromatographic method. A total of 38 different fatty acids were determined in the fatty acid composition of rainbow trout. Polyunsaturated fatty acids (PUFAs) were found to be higher than saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) in all seasons. Oleic acid (C18:1 9) is the major MUFA in all seasons. Palmitic acid (C16:0) was identified as the major SFA infour seasons. Docosahexaenoic acid (C22:6 3), linoleic acid (C18:2 6) and eicosapentaenoic acid (C20:5 3) had the highest levels among the PUFAs. In the present study, 3 /6 ratios were found to be 1.24, 1.68, 0.61 and 0.98 in spring, summer, autumn and winter, respectively

Release Time Scheduling and Hub Location for Next-Day Delivery

Cataloged from PDF version of article.Inspired by a real-life problem faced by one of the largest ground-based cargo companies of Turkey, the current study introduces a new facet to the hub location literature. The release time scheduling and hub location problem aims to select a specified number of hubs from a fixed set of demand centers, to allocate each demand center to a hub, and to decide on the release times of trucks from each demand center in such a way that the total amount of cargo guaranteed to be delivered to every potential destination by the next day is not below a threshold and the total routing cost is minimized. The paper introduces integer programming models to solve this problem in the special cases when the cargo uniformly arrives to each demand center during the day and the more realistic pattern of when the cargo arrivals exhibit a piecewise linear form. Several classes of valid inequalities are proposed to strengthen the formulations. Extensions with multiple service levels and discrete sets for release times are also discussed. Computational results show the computational viability of the models under realistic scenarios as well as the validity of the proposed problems in answering several interesting questions from the cargo sector’s perspective

Vesicles in solutions of hard rods

The surface free energy of ideal hard rods near curved hard surfaces is determined to second order in curvature for surfaces of general shape. In accordance with previous results for spherical and cylindrical surfaces it is found that this quantity is non-analytical when one of the principal curvatures changes signs. This prohibits writing it in the common Helfrich form. It is shown that the non-analytical terms are the same for any aspect ratio of the rods. These results are used to find the equilibrium shape of vesicles immersed in solutions of rod-like (colloidal) particles. The presence of the particles induces a change in the equilibrium shape and to a shift of the prolate-oblate transition in the vesicle phase diagram, which are calculated within the framework of the spontaneous curvature model. As a consequence of the special form of the energy contribution due to the rods these changes cannot be accounted for by a simple rescaling of the elastic constants of the vesicle as for solutions of spherical colloids or polymers.Comment: 11 pages, 7 figures, submitted to Phys. Rev.

Penggunaan Limbah Ikan Leubiem (Chanthidermis maculatus) dalam Ransum terhadap Kelayakan Usaha Itik Petelur Fase Starter

Pakan merupakan faktor yang memengaruhi biaya produksi itik petelur, biaya pakan mencapai 70% dari total biaya produksi, untuk itu diperlukan pakan alternatif yang dapat mengurangi biaya produksi, salah satunya adalah limbah ikan leubiem (Chanthidermis maculatus). Penelitian bertujuan untuk mengevaluasi penggunaan limbah ikan leubiem dalam ransum terhadap kelayakan usaha itik petelur fase starter. Materi penelitian yang digunakan 500 ekor itik petelur umur 1 hari (DOD). Perlakuan ransum yang digunakan: P1 (ransum kontrol/tanpa limbah ikan leubiem), P2 (ransum mengandung 10% kulit ikan leubiem), P3 (ransum mengandung 10% kepala ikan leubiem), P4 (ransum mengandung 10% tulang ikan leubiem) dan P5 (ransum mengandung 10% kombinasi limbah ikan leubiem). Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) yang terdiri 5 perlakuan dan 4 ulangan. Variabel yang diamati adalah: harga ransum, biaya produksi, IOFC, penerimaan (hasil penjualan), keuntungan dan kelayakan usaha. Data yang diperoleh ditabulasi dan dikalkulasi sesuai dengan variabel penelitian. Hasil penelitian menunjukkan bahwa harga ransum itik petelur fase starter berkisar antara Rp. 4.081,- 5.205,-/kg. Total biaya produksi terendah terdapat pada perlakuan ransum P5 yaitu Rp. 26.270,-/ekor. Penerimaan diperoleh dari hasil penjualan itik petelur fase starter berdasarkan bobot hidup Rp. 40.000/kg. IOFC dan keuntungan tertinggi diperoleh pada perlakuan ransum P5 yaitu Rp. 17.318,-/ekor. Kelayakan usaha berdasarkan nilai BC dan RC ratio dari semua perlakuan ransum menunjukkan nilai yang diperoleh lebih besar dari 0 dan 1. Hal ini menunjukkan bahwa usaha itik petelur menguntungkan dan layak diusahakan. Disimpulkan bahwa usaha peternakan itik petelur fase starter dengan penggunaan limbah ikan leubiem dalam ransum layak untuk diteruskan dan menguntungkan

The latest arrival hub location problem for cargo delivery systems with stopovers

Cataloged from PDF version of article.In this paper, we concentrate on the service structure of ground-transportation based cargo delivery companies. The transient times that arise from nonsimultaneous arrivals at hubs (typically spent for unloading, loading, and sorting operations) can constitute a significant portion of the total delivery time for cargo delivery systems. The latest arrival hub location problem is a new minimax model that focuses on the minimization of the arrival time of the last item to arrive, taking into account journey times as well as the transient times at hubs. We first focus on a typical cargo delivery firm operating in Turkey and observe that stopovers are essential components of a ground-based cargo delivery system. The existing formulations of the hub location problem in the literature do not allow stopovers since they assume direct connections between demand centers and hubs. In this paper, we propose a generic mathematical model, which allows stopovers for the latest arrival hub location problem. We improve the model using valid inequalities and lifting. We present computational results using data from the US and Turkey. 2007 Elsevier Ltd. All rights reserved

The vendor location problem

The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two versions of the problem with different objectives: maximizing the total profit and maximizing the demand covered. The demand and profit generated by a demand point are functions of the distance to the vendor. We propose integer programming models for both versions of the vendor location problem. We then prove that both are strongly NP-hard and we derive several families of valid inequalities to strengthen our formulations. We report the outcomes of a computational study where we investigate the effect of valid inequalities in reducing the duality gaps and the solution times for the vendor location problem. © 2011 Elsevier Ltd. All rights reserved