scholarly journals Coverage versus response time objectives in ambulance location

2021 ◽  
Author(s):  
Ludmila Janosikova ◽  
Peter Jankovic ◽  
Marek Kvet ◽  
Frederika Zajacova
Keyword(s):  
Response Time ◽  
Large Scale ◽  
Programming Model ◽  
Slovak Republic ◽  
Type Model ◽  
Computer Simulation Model ◽  
Risk Patients ◽  
Detailed Computer ◽  
Single Response ◽  
Short Time

Abstract Background: This paper deals with the location of emergency medical stations in a large-scale area. Operations research tools are used to design a new infrastructure that reflects demographic changes.Methods: A bi-criteria mathematical programming model is proposed. The criteria include the accessibility of high-priority patients in a short time limit and response time of all patients. The model is compared with the p-median model with a single response time objective and with a hierarchical pq-median model that considers different vehicle types. A detailed computer simulation model is used to evaluate the solutions.Results: The methodology is verified in the conditions of the Slovak Republic using real historical data on ambulance trips. Considerable improvements regarding the average response time, coverage of population and coverage of high-risk patients can be achieved by redistributing current stations. In a large-scale area, the coverage objective does not work well. It does not outperform the response time objective that enables saving more lives. The best results are achieved by the hierarchical median-type model.Conclusions: The resulting distribution of ambulances significantly improves the accessibility of urgent health care to patients.

scholarly journals Coverage versus response time objectives in ambulance location

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Ľudmila Jánošíková ◽  
Peter Jankovič ◽  
Marek Kvet ◽  
Frederika Zajacová
Keyword(s):  
Mathematical Programming ◽  
Response Time ◽  
Urban Areas ◽  
Slovak Republic ◽  
Time Limit ◽  
Type Model ◽  
Computer Simulation Model ◽  
Average Response ◽  
Average Response Time ◽  
Emergency Medical

Abstract Background This paper deals with the location of emergency medical stations where ambulances waiting to be dispatched are parked. The literature reports a lot of mathematical programming models used to optimize station locations. Most studies evaluate the models only analytically applying the same simplifying assumptions that were used in the modelling phase. In addition, they concentrate on systems operating one type of emergency units in homogeneous urban areas. The goal of our study is to identify which optimization criterion the emergency medical service (EMS) outcomes benefit from the most and which model should be used to design tiered systems in large urban–rural areas. Methods A bi-criteria mathematical programming model is proposed. The criteria include the accessibility of high-priority patients within a short time limit and average response time to all patients. This model is being compared to the p-median model with a single response time objective and to a hierarchical pq-median model that considers two different vehicle types. A detailed computer simulation model is used to evaluate the solutions. The methodology is verified in the conditions of the Slovak Republic using real historical data on 149,474 ambulance trips performed in 2015. Results All mathematical models improve EMS performance by relocating some stations compared to the current distribution. The best results are achieved by the hierarchical median-type model. The average response time is reduced by 58 s, the number of calls responded to within 15 min is increased by 5% and the number of high-priority calls responded to within 8 min by 6%. Conclusions The EMS systems operating in heterogeneous areas should be designed to minimize response times, and not to maximize the number of calls served within a given time limit.

Modified Delay Scheduling: A Heuristic Approach for Hadoop Scheduling to Improve Fairness and Response Time

2015 ◽  
Vol 25 (04) ◽  
pp. 1550009 ◽  
Author(s):  
N. P. Gopalan ◽  
S. Suresh
Keyword(s):  
Response Time ◽  
Large Scale ◽  
Programming Model ◽  
Data Locality ◽  
Data Intensive ◽  
Large Scale Data ◽  
Fair Scheduler ◽  
Hadoop Clusters ◽  
Data Intensive Applications ◽  
Scale Data

Hadoop is a widely used open source implementation of MapReduce which is a popular programming model for parallel processing large scale data intensive applications in a cloud environment. Sharing Hadoop clusters has a tradeoff between fairness and data locality. When launching a local task is not possible, Hadoop Fair Scheduler (HFS) with delay scheduling postpones the node allocation for a while to a job which is to be scheduled next as per fairness to achieve high locality. This waiting becomes waste when the desired locality could not be achieved within a reasonable period. In this paper, a modified delay scheduling in HFS is proposed and implemented in Hadoop. It avoids the aforementioned waiting of delay scheduler if achieving locality is not possible. Instead of blindly waiting for a local node, the proposed algorithm first estimates the time to wait for a local node for the job and avoids waiting wherever achieving locality is not possible within the predefined delay threshold while accomplishing same locality. The performance of the proposed algorithm is evaluated by extensive experiments and it has been observed that the algorithm works significantly better in terms of response time and fairness achieving up to 20% speedup and up to 38% fairness in certain cases.

Towards Control of an Estuary

1987 ◽  
Vol 19 (9) ◽  
pp. 155-174
Author(s):  
Henk L. F. Saeijs
Keyword(s):  
Shallow Water ◽  
Storm Surge ◽  
Salt Marshes ◽  
Large Scale ◽  
Western Europe ◽  
Oxygen Depletion ◽  
Negative Effects ◽  
Intertidal Flats ◽  
Environmental Consequences ◽  
Short Time

The Delta Project is in its final stage. In 1974 it was subjected to political reconsideration, but it is scheduled now for completion in 1987. The final touches are being put to the storm-surge barrier and two compartment dams that divide the Oosterschelde into three areas: one tidal, one with reduced tide, and one a freshwater lake. Compartmentalization will result in 13% of channels, 45% of intertidal flats and 59% of salt marshes being lost. There is a net gain of 7% of shallow-water areas. Human interventions with large scale impacts are not new in the Oosterschelde but the large scale and short time in which these interventions are taking place are, as is the creation of a controlled tidal system. This article focusses on the area with reduced tide and compares resent day and expected characteristics. In this reduced tidal part salt marshes will extend by 30–70%; intertidal flats will erode to a lower level and at their edges, and the area of shallow water will increase by 47%. Biomass production on the intertidal flats will decrease, with consequences for crustaceans, fishes and birds. The maximum number of waders counted on one day and the number of ‘bird-days' will decrease drastically, with negative effects for the wader populations of western Europe. The net area with a hard substratum in the reduced tidal part has more than doubled. Channels will become shallower. Detritus import will not change significantly. Stratification and oxygen depletion will be rare and local. The operation of the storm-surge barrier and the closure strategy chosen are very important for the ecosystem. Two optional closure strategies can be followed without any additional environmental consequences. It was essential to determine a clearly defined plan of action for the whole area, and to make land-use choices from the outset. How this was done is briefly described.

scholarly journals Wind Farm Cable Connection Layout Optimization with Several Substations

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3615
Author(s):  
Adelaide Cerveira ◽  
Eduardo J. Solteiro Pires ◽  
José Baptista
Keyword(s):  
Energy Production ◽  
Wind Farm ◽  
Programming Model ◽  
Optimal Solution ◽  
Wind Farms ◽  
Green Energy ◽  
Fossil Energy ◽  
Proposed Model ◽  
Short Time ◽  
Cable Connection

Green energy has become a media issue due to climate changes, and consequently, the population has become more aware of pollution. Wind farms are an essential energy production alternative to fossil energy. The incentive to produce wind energy was a government policy some decades ago to decrease carbon emissions. In recent decades, wind farms were formed by a substation and a couple of turbines. Nowadays, wind farms are designed with hundreds of turbines requiring more than one substation. This paper formulates an integer linear programming model to design wind farms’ cable layout with several turbines. The proposed model obtains the optimal solution considering different cable types, infrastructure costs, and energy losses. An additional constraint was considered to limit the number of cables that cross a walkway, i.e., the number of connections between a set of wind turbines and the remaining wind farm. Furthermore, considering a discrete set of possible turbine locations, the model allows identifying those that should be present in the optimal solution, thereby addressing the optimal location of the substation(s) in the wind farm. The paper illustrates solutions and the associated costs of two wind farms, with up to 102 turbines and three substations in the optimal solution, selected among sixteen possible places. The optimal solutions are obtained in a short time.

scholarly journals Environmental Engineering Techniques to Restore Degraded Posidonia oceanica Meadows

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 661
Author(s):  
Luigi Piazzi ◽  
Stefano Acunto ◽  
Francesca Frau ◽  
Fabrizio Atzori ◽  
Maria Francesca Cinti ◽  
...  
Keyword(s):  
Large Scale ◽  
Natural Habitat ◽  
Cost Benefit ◽  
Cost Effective ◽  
Posidonia Oceanica ◽  
Environmental Engineering ◽  
Bottom Surface ◽  
Sessile Invertebrates ◽  
Set Up ◽  
Short Time

Seagrass planting techniques have shown to be an effective tool for restoring degraded meadows and ecosystem function. In the Mediterranean Sea, most restoration efforts have been addressed to the endemic seagrass Posidonia oceanica, but cost-benefit analyses have shown unpromising results. This study aimed at evaluating the effectiveness of environmental engineering techniques generally employed in terrestrial systems to restore the P. oceanica meadows: two different restoration efforts were considered, either exploring non-degradable mats or, for the first time, degradable mats. Both of them provided encouraging results, as the loss of transplanting plots was null or very low and the survival of cuttings stabilized to about 50%. Data collected are to be considered positive as the survived cuttings are enough to allow the future spread of the patches. The utilized techniques provided a cost-effective restoration tool likely affordable for large-scale projects, as the methods allowed to set up a wide bottom surface to restore in a relatively short time without any particular expensive device. Moreover, the mats, comparing with other anchoring methods, enhanced the colonization of other organisms such as macroalgae and sessile invertebrates, contributing to generate a natural habitat.

scholarly journals Synthesis of Metal Organic Frameworks by Ball-Milling

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Cheng-An Tao ◽  
Jian-Fang Wang
Keyword(s):  
Ball Milling ◽  
Large Scale ◽  
Raw Materials ◽  
Metal Organic Frameworks ◽  
Research Topic ◽  
Mass Ratio ◽  
Time Consumption ◽  
Metal Organic ◽  
Short Time ◽  
Made In

Metal-organic frameworks (MOFs) have been used in adsorption, separation, catalysis, sensing, photo/electro/magnetics, and biomedical fields because of their unique periodic pore structure and excellent properties and have become a hot research topic in recent years. Ball milling is a method of small pollution, short time-consumption, and large-scale synthesis of MOFs. In recent years, many important advances have been made. In this paper, the influencing factors of MOFs synthesized by grinding were reviewed systematically from four aspects: auxiliary additives, metal sources, organic linkers, and reaction specific conditions (such as frequency, reaction time, and mass ratio of ball and raw materials). The prospect for the future development of the synthesis of MOFs by grinding was proposed.

scholarly journals A robust-heuristic optimization approach to a green supply chain design with consideration of assorted vehicle types and carbon policies under uncertainty

2021 ◽  
Author(s):  
Zahra Homayouni ◽  
Mir Saman Pishvaee ◽  
Hamed Jahani ◽  
Dmitry Ivanov
Keyword(s):  
Supply Chains ◽  
Large Scale ◽  
Programming Model ◽  
Supply Chain Design ◽  
Heuristic Optimization ◽  
Optimization Approach ◽  
Economic Uncertainty ◽  
Cap And Trade ◽  
Sustainable Logistics ◽  
Goal Programming Model

AbstractAdoption of carbon regulation mechanisms facilitates an evolution toward green and sustainable supply chains followed by an increased complexity. Through the development and usage of a multi-choice goal programming model solved by an improved algorithm, this article investigates sustainability strategies for carbon regulations mechanisms. We first propose a sustainable logistics model that considers assorted vehicle types and gas emissions involved with product transportation. We then construct a bi-objective model that minimizes total cost as the first objective function and follows environmental considerations in the second one. With our novel robust-heuristic optimization approach, we seek to support the decision-makers in comparison and selection of carbon emission policies in supply chains in complex settings with assorted vehicle types, demand and economic uncertainty. We deploy our model in a case-study to evaluate and analyse two carbon reduction policies, i.e., carbon-tax and cap-and-trade policies. The results demonstrate that our robust-heuristic methodology can efficiently deal with demand and economic uncertainty, especially in large-scale problems. Our findings suggest that governmental incentives for a cap-and-trade policy would be more effective for supply chains in lowering pollution by investing in cleaner technologies and adopting greener practices.

Role of N-Acetylcysteine in the Prevention of Radiocontrast-Induced Nephropathy

2002 ◽  
Vol 36 (9) ◽  
pp. 1466-1470 ◽  
Author(s):  
Donald F Brophy
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Large Scale ◽  
English Language ◽  
Small Animal ◽  
Human Studies ◽  
Animal Trials ◽  
Study Selection ◽  
Risk Patients

OBJECTIVE: To examine the role of N-acetylcysteine (NAC) in the prevention of radiocontrast—induced nephropathy (RIN). DATA SOURCES: A literature search of MEDLINE (1966–December 2001) was performed using the following search terms: N-acetylcysteine, nephropathy, acute renal failure, and radiocontrast. STUDY SELECTION: Pertinent English-language animal and human studies were reviewed. DATA SYNTHESIS: Few small animal trials have demonstrated that NAC significantly prevents the development or reduces the severity of acute renal failure. Two human studies demonstrated NAC significantly reduces the occurrence of RIN. CONCLUSIONS: NAC may reduce the occurrence of RIN in high-risk patients. Further large-scale studies are needed to corroborate findings from earlier trials.

scholarly journals Shift Scheduling of Short Time Workers in Large-Scale Home Improvement Center by using Cooperative Evolution

MENDEL ◽  
2017 ◽  
Vol 23 (1) ◽  
pp. 21-28
Author(s):  
Makoto Ohki
Keyword(s):  
Large Scale ◽  
Shift Scheduling ◽  
Time Zone ◽  
Cooperative Evolution ◽  
Shift Schedule ◽  
Home Improvement ◽  
Mutation Operators ◽  
Break Time ◽  
Working Day ◽  
Short Time

There are a lot of large-scale Home Improvement Center (HIC) in Japan. In the large-scale HIC,about hundred short time workers are registered. And about forty workers are working every day. A managercreates a monthly shift schedule. The manager selects the workers required for each working day, assigns theworking time and break time for each worker and also work placement. Because there are many requirementsfor the scheduling, the scheduling consumes time costs and efforts. Therefore, we propose the technique to createand optimize the schedule of the short time workers in order to reduce the burden of the manager. A cooperativeevolution is applied for generating and optimizing the shift schedule of short time worker. Several problems hasbeen found in carrying out this research. This paper proposes techniques to automatically create and optimize theshift schedule of workers in large-scale HIC by using a Cooperative Evolution (CE), to solve the situation thatmany workers concentrate in a speci c time zone, and to solve the situation where many breaks are concentratedin a speci c break time zone, and an effective mutation operators.

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