scholarly journals Alternative methods for calculating optimal safety stock levels

2017 ◽  
Author(s):  
◽  
Ashkan Mirzaee
Keyword(s):  
Large Scale ◽  
Hybrid Approach ◽  
Solution Procedure ◽  
Alternative Methods ◽  
Random Demand ◽  
Safety Stock ◽  
Service Levels ◽  
Gamma Distributions ◽  
Proposed Model

This work considers the problem of safety stock levels for the production of multiple items, each with random demand, across multiple facilities. The traditional methodology for calculating safety stock is discussed and an alternative method for improving service levels is offered. Normal and Gamma distributions are considered to estimate safety stock levels, and the performance of both models, along with a hybrid approach, are tested on a large-scale case study example. The results of this case study indicate that a better inventory policy with less underage and overage cost can be achieved by using the proposed model and solution procedure.

scholarly journals Sustainable Ship Loading Planning for Prefabricated Products in the Construction Industry

2020 ◽  
Vol 12 (21) ◽  
pp. 8905
Author(s):  
Wen Yi ◽  
Robyn Phipps ◽  
Hans Wang
Keyword(s):  
Construction Industry ◽  
Large Scale ◽  
Transportation Cost ◽  
Sustainable Transportation ◽  
Construction Site ◽  
Integer Optimization ◽  
Construction Sites ◽  
Capacity Limits ◽  
Proposed Model

This paper focuses on sustainable transportation of prefab products from factories to construction sites by ship. Since the transportation cost for all the prefab products of a construction site is mainly dependent on the number of cargo holds used on ships, a loading plan for prefab products that minimizes the number of holds required is highly desirable. This paper is therefore devoted to the development of an optimal loading plan that decides which prefab products are loaded into each cargo hold and how to pack these prefab products into the holds so that as few holds as possible are used. We formulate the problem as a large-scale integer optimization model whose objective function is to minimize the total number of cargo holds used and whose constraints represent the cargo hold capacity limits. We develop a heuristic to solve the problem and obtain a high-quality solution. We have tested the model and algorithm on a case study that includes 20 prefab products. We find that different cargo holds carry prefab products that have quite different densities. Moreover, the orientations of many prefab products are different from their default orientations. The results demonstrate the applicability of the proposed model and algorithm.

scholarly journals What is a good pattern of life model? Guidance for simulations

SIMULATION ◽  
2018 ◽  
Vol 95 (8) ◽  
pp. 693-706
Author(s):  
Barry G Silverman ◽  
Gnana Bharathy ◽  
Nathan Weyer
Keyword(s):  
Large Scale ◽  
First Generation ◽  
Hybrid Approach ◽  
Daily Activities ◽  
Human Behaviors ◽  
The World ◽  
Life Model ◽  
Good Pattern ◽  
Definition Of

We have been modeling an ever-increasing scale of applications with agents that simulate the pattern of life (PoL) and real-world human behaviors in diverse regions of the world. The goal is to support sociocultural training and analysis. To measure progress, we propose the definition of a measure of goodness for such simulated agents, and review the issues and challenges associated with first-generation (1G) agents. Then we present a second generation (2G) agent hybrid approach that seeks to improve realism in terms of emergent daily activities, social awareness, and micro-decision making in simulations. We offer a PoL case study with a mix of 1G and 2G approaches that was able to replace the pucksters and avatar operators needed in large-scale immersion exercises. We conclude by observing that a 1G PoL simulation might still be best where large-scale, pre-scripted training scenarios will suffice, while the 2G approach will be important for analysis or if it is vital to learn about adaptive opponents or unexpected or emergent effects of actions. Lessons are shared about ways to blend 1G and 2G approaches to get the best of each.

scholarly journals Container Slot Co-Allocation Planning with Joint Fleet Agreement in a Round Voyage for Liner Shipping

2013 ◽  
Vol 66 (4) ◽  
pp. 589-603 ◽  
Author(s):  
Jihong Chen ◽  
Shmuel Yahalom
Keyword(s):  
Large Scale ◽  
Economies Of Scale ◽  
Programming Model ◽  
Liner Shipping ◽  
Shipping Industry ◽  
Round Trip ◽  
Factors Affecting ◽  
Proposed Model ◽  
Allocation Planning

In the liner shipping market carriers share container slots to offer better service and realize economies of scale. This paper studies slot co-allocation planning for a joint fleet in a round trip for a shipping alliance in the liner shipping industry. In particular, a conceptual model is developed based on joint fleet and slot co-allocation management. The factors affecting slot co-allocation planning are explored in detail. A large-scale integer programming model is formulated to guide carriers in an alliance in pursuing an optimal slot co-allocation strategy. In contrast to the existing research, this approach leads to a more accurate representation of the situation for cooperative services in the liner shipping market. Extensive numerical experiments based on a true Asia-Europe cooperative route of COSCO and HANJIN show that the proposed model can be efficiently solved by LINGO11.0 for the case study. The computational results suggest that the mechanism and model can be used to benefit carriers in making better decisions in shipping cooperation services.

Modeling Queue Service System in Pedestrian Simulation

2011 ◽  
Vol 187 ◽  
pp. 1-6 ◽  
Author(s):  
De Wei Li ◽  
Bao Ming Han
Keyword(s):  
Large Scale ◽  
Service System ◽  
Safety Control ◽  
Large Scale Systems ◽  
Queue System ◽  
Proposed Model ◽  
Machine Layout ◽  
Pedestrian Simulation ◽  
Grid Based

Pedestrian simulation is widely used on the assessment of facility design and crowd safety control. It proposed a grid-based model of queue simulation system considering human physiology and psychology. Both logic queue system and animation queue system are modeled separately. Deadlock deal mechanism is designed. The proposed model established a good interface between the pedestrian behavior, queue system and animation. It can reproduce phenomenon like traffic shock wave effectively. A case study is shown by simulation of ticket vendor machine layout assessment in Beijing South Railway Station. It concluded that the model is effective and adapted to large scale systems.

scholarly journals False Sequential Command Attack of Large-Scale Cyber-Physical Systems

Electronics ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 176 ◽  
Author(s):  
Yinqiao Xiong ◽  
Ziyu Yang ◽  
Baoyao Wang ◽  
Peng Xun ◽  
Tiantian Deng
Keyword(s):  
Physical Process ◽  
Large Scale ◽  
Cyber Physical Systems ◽  
Physical Systems ◽  
Attack Model ◽  
Command Sequence ◽  
Proposed Model ◽  
Feedback Data ◽  
Bad Data

Previous studies have demonstrated that false commands can cause severe damage to large-scale cyber-physical systems (CPSs). We focus on a kind of threat called false sequential command attack, with which attackers can generate false sequential commands, resulting in the illegal control of the physical process. We present a feasible attack model. Attackers delay the disaggregation of former commands by manipulating maliciously sub-controllers. Simultaneously, bad feedback data is injected to defeat the controller to issue latter commands. Thus, false command sequence is executed and the disruption of physical process can be obtained. It is also difficult for the detector to identify such attacks as injecting bad data. We also discuss other possible attack paths and analyze the corresponding disadvantages. Compared with other paths, the proposed model is more feasible and has more difficulties to be detected. A case study is given to validate the feasibility and effectiveness of proposed false sequential command attack model. Finally, we discuss the possible countermeasure.

scholarly journals A stochastic location and allocation model for critical items to response large-scale emergencies: A case of Turkey

2016 ◽  
Vol 7 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Erkan Celik ◽  
Nezir Aydin ◽  
Alev Taskin Gumus
Keyword(s):  
Large Scale ◽  
Programming Model ◽  
Mixed Integer ◽  
Distribution Centers ◽  
Allocation Model ◽  
Proposed Model ◽  
Stochastic Mixed Integer Programming ◽  
Stochastic Location ◽  
Relief Organizations

This paper aims to decide on the number of facilities and their locations, procurement for pre and post-disaster, and allocation to mitigate the effects of large-scale emergencies. A two-stage stochastic mixed integer programming model is proposed that combines facility location- prepositioning, decisions on pre-stocking levels for emergency supplies, and allocation of located distribution centers (DCs) to affected locations and distribution of those supplies to several demand locations after large-scale emergencies with uncertainty in demand. Also, the use of the model is demonstrated through a case study for prepositioning of supplies in probable large-scale emergencies in the eastern and southeastern Anatolian sides of Turkey. The results provide a framework for relief organizations to determine the location and number of DCs in different settings, by using the proposed model considering the main parameters, as; capacity of facilities, probability of being affected for each demand points, severity of events, maximum distance between a demand point and distribution center. 

scholarly journals A Case Study on Scientific Attempt to Turn Agriculture Scetor Sustainable, Profitable and Attractive Through Innovative Aquaphonic Farming Methods in Cuttack and Khordha Districts of Odisha, India

2020 ◽  
Vol 5 (8) ◽  
pp. 1264-1268
Author(s):  
Usharani Sahu
Keyword(s):  
Food Security ◽  
Agricultural Production ◽  
Large Scale ◽  
Alternative Methods ◽  
Innovative Technology ◽  
Wide Spread ◽  
Smart Technology ◽  
Financial Return ◽  
Support Price

Decreasing availability of land for farming due to Urbanization and Industrialization has further complicated Wide spread difference between cost of Agricultural Production-Minimum Support Price (MSP). To resolve the issues of viability in terms of economic & financial return and to find out alternative methods have to be applied in farming sector.Use of innovative technology ,the less numners of persons have been employed which obtained better results,less area under innovative farming has resulted in higher yield..As per suitability non-traditional methods to be implemented at large scale by the assistance of Government mechanism for the betterment of society. Agriculture has to be climate smart, technology driven, profit generating and sustainable to meet the need of food security of the country

A Family With Autosomal-Dominant Progressive Sensorineural Hearing Loss

1996 ◽  
Vol 5 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Chris Halpin ◽  
Barbara Herrmann ◽  
Margaret Whearty
Keyword(s):  
Speech Production ◽  
Hearing Aids ◽  
Role Models ◽  
Speech Intelligibility ◽  
Large Scale ◽  
Speech Language Pathology ◽  
The Family ◽  
Patient Will ◽  
Language Pathology

The family described in this article provides an unusual opportunity to relate findings from genetic, histological, electrophysiological, psychophysical, and rehabilitative investigation. Although the total number evaluated is large (49), the known, living affected population is smaller (14), and these are spread from age 20 to age 59. As a result, the findings described above are those of a large-scale case study. Clearly, more data will be available through longitudinal study of the individuals documented in the course of this investigation but, given the slow nature of the progression in this disease, such studies will be undertaken after an interval of several years. The general picture presented to the audiologist who must rehabilitate these cases is that of a progressive cochlear degeneration that affects only thresholds at first, and then rapidly diminishes speech intelligibility. The expected result is that, after normal language development, the patient may accept hearing aids well, encouraged by the support of the family. Performance and satisfaction with the hearing aids is good, until the onset of the speech intelligibility loss, at which time the patient will encounter serious difficulties and may reject hearing aids as unhelpful. As the histological and electrophysiological results indicate, however, the eighth nerve remains viable, especially in the younger affected members, and success with cochlear implantation may be expected. Audiologic counseling efforts are aided by the presence of role models and support from the other affected members of the family. Speech-language pathology services were not considered important by the members of this family since their speech production developed normally and has remained very good. Self-correction of speech was supported by hearing aids and cochlear implants (Case 5’s speech production was documented in Perkell, Lane, Svirsky, & Webster, 1992). These patients received genetic counseling and, due to the high penetrance of the disease, exhibited serious concerns regarding future generations and the hope of a cure.

The Boeing 787 Dreamliner--A case study in large-scale design integration

2008 ◽  
Author(s):  
D. L. McMullin ◽  
A. R. Jacobsen ◽  
D. C. Carvan ◽  
R. J. Gardner ◽  
J. A. Goegan ◽  
...  
Keyword(s):  
Large Scale ◽  
Design Integration ◽  
Scale Design
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