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1

Qi, Yuan, Xin Chen, Jiaqing Zhang, Yaoyao Li, and Daolin Zhu. "How Do Rising Farmland Costs Affect Fertilizer Use Efficiency? Evidence from Gansu and Jiangsu, China." Land 11, no. 10 (October 6, 2022): 1730. http://dx.doi.org/10.3390/land11101730.

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As the farmland transfer market in China develops, moderate-scale operations increasingly grow but without much improvement in fertilizer use efficiency. This study theoretically analyzes the mechanism and effect of rising farmland costs on fertilizer use efficiency using multiple quadratic regression and mediating effects models. It empirically tests a micro-sample of 806 farmers in Gansu and Jiangsu provinces in China from two dimensions: the full samples and farmer heterogeneity. The results showed 0.544 as the average fertilizer use efficiency (hereinafter, fe) of farmers in Gansu and Jiangsu, highlighting the severe loss of fe caused by excessive fertilizer inputs. The multiple quadratic regression model further revealed an inverted U-shaped relationship between farmland costs and fe, with the U-shaped curve showing a remarkable inflection point at the USD 708/mu mark. When farmland costs are excessive (cost > CNY 708/mu), the increase in farmland costs inhibits the fe. An investigation of the corresponding impact mechanism for this scenario (i.e., cost > USD 708/mu) revealed that farmland costs directly suppress fe (−0.485) by distorting the fertilizer factor substitution effect and indirectly suppress fe (−0.037) by impeding the technology spillover effect of production specialization and production scale-up. We also found heterogeneity between two groups: ordinary farmers and new agricultural operators (e.g., large grain and family farmers), with the peak kernel density function of fe of new agricultural operators (0.85) being much higher than that of ordinary farmers (0.30). Moreover, the multiple quadratic regression between the groups revealed a lower inflection point for ordinary farmers (CNY 638/mu) than new agricultural operators (CNY 823/mu), highlighting that the fe of ordinary farmers was more likely to be inhibited by the excessive rise in farmland costs. To promote the sustainable development of China’s agricultural production, we propose reducing the cost of farmland, promoting service-scale operations, and fostering new agricultural operators.
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2

Bertsimas, Dimitris, Arthur Delarue, and Sebastien Martin. "Optimizing schools’ start time and bus routes." Proceedings of the National Academy of Sciences 116, no. 13 (March 12, 2019): 5943–48. http://dx.doi.org/10.1073/pnas.1811462116.

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Maintaining a fleet of buses to transport students to school is a major expense for school districts. To reduce costs by reusing buses between schools, many districts spread start times across the morning. However, assigning each school a time involves estimating the impact on transportation costs and reconciling additional competing objectives. Facing this intricate optimization problem, school districts must resort to ad hoc approaches, which can be expensive, inequitable, and even detrimental to student health. For example, there is medical evidence that early high school starts are impacting the development of an entire generation of students and constitute a major public health crisis. We present an optimization model for the school time selection problem (STSP), which relies on a school bus routing algorithm that we call biobjective routing decomposition (BiRD). BiRD leverages a natural decomposition of the routing problem, computing and combining subproblem solutions via mixed integer optimization. It significantly outperforms state-of-the-art routing methods, and its implementation in Boston has led to $5 million in yearly savings, maintaining service quality for students despite a 50-bus fleet reduction. Using BiRD, we construct a tractable proxy to transportation costs, allowing the formulation of the STSP as a multiobjective generalized quadratic assignment problem. Local search methods provide high-quality solutions, allowing school districts to explore tradeoffs between competing priorities and choose times that best fulfill community needs. In December 2017, the development of this method led the Boston School Committee to unanimously approve the first school start time reform in 30 years.
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3

Chen, Chen, Xinrui Song, and Junli Zhu. "Impact of slack resources on healthcare costs in tertiary and secondary hospitals: a panel data study of public hospitals in Beijing from 2015 to 2019." BMJ Open 13, no. 4 (April 2023): e068383. http://dx.doi.org/10.1136/bmjopen-2022-068383.

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ObjectiveThis study aims to explore the relationship between slack resources and cost consumption index in tertiary and secondary hospitals and to provide targeted healthcare resource utilisation recommendations for tertiary and secondary hospital managers.DesignThis is a panel data study of 51 public hospitals in Beijing from 2015 to 2019.SettingTertiary and secondary public hospitals in Beijing. Data envelope analysis was used to calculate the slack resources. Regression models were used to explore the relationship between slack resources and healthcare costs.ParticipantsA total of 255 observations were collected from 33 tertiary hospitals and 18 secondary hospitals.Outcome measuresSlack resources and healthcare costs in tertiary and secondary public hospitals in Beijing from 2015 to 2019. Linear or curve relationship between slack resources and healthcare costs in tertiary and secondary hospitals.ResultsThe cost of healthcare in tertiary hospitals has always been higher than in secondary hospitals, and the slack resources in secondary hospitals have always been worse than in tertiary hospitals. For tertiary hospitals, the cubic coefficient of slack resources is significant (β=−12.914, p<0.01) and the R2of cubic regression is increased compared with linear and quadratic regression models, so there is a transposed S-shaped relationship between slack resources and cost consumption index. For secondary hospitals, only the first-order coefficient of slack resources in the linear regression was significant (β=0.179, p<0.05), so slack resources in secondary hospitals were positively related to the cost consumption index.ConclusionsThis study shows that slack resources’ impact on healthcare costs differs in tertiary and secondary public hospitals. For tertiary hospitals, slack should be kept within a reasonable range to control excessive growth in healthcare costs. In secondary hospitals, keeping too many slack resources is not ideal, so managers should adopt strategies to improve competitiveness and service transformation.
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4

Niu, Zhiqiang, Shengnan Wu, and Xuesong (Simon) Zhou. "Efficient Mathematical Lower Bounds for City Logistics Distribution Network with Intra-Echelon Connection of Facilities: Bridging the Gap from Theoretical Model Formulations to Practical Solutions." Algorithms 16, no. 5 (May 12, 2023): 252. http://dx.doi.org/10.3390/a16050252.

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Focusing on the dynamic improvement of the underlying service network configuration, this paper aims to address a specific challenge of redesigning a multi-echelon city logistics distribution network. By considering the intra-echelon connection of facilities within the same layer of echelon, we propose a new distribution network design model by reformulating the classical quadratic assignment problem (QAP). To minimize the overall transportation costs, the proposed model jointly optimizes two types of decisions to enable agile distribution with dynamic “shortcuts”: (i) the allocation of warehouses to supply the corresponding distribution centers (DCs), and (ii) the demand coverage decision from distribution centers to delivery stations. Furthermore, a customized branch-and-bound algorithm is developed, where the lower bound is obtained by adopting Gilmore and Lawler lower Bound (GLB) for QAP. We conduct extensive computational experiments, highlighting the significant contribution of GLB-oriented lower bound, to obtain practical solutions; this type of efficient mathematical lower bounds offers a powerful tool for balancing theoretical research ideas with practical and industrial applicability.
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5

WAN, Eric Yuk Fai, Weng Yee Chin, Esther Yee Tak Yu, Julie Chen, Emily Tsui Yee Tse, Carlos King Ho Wong, Tony King Hang Ha, David Vai Kiong Chao, Wendy Wing Sze Tsui, and Cindy Lo Kuen Lam. "Retrospective cohort study to investigate the 10-year trajectories of disease patterns in patients with hypertension and/or diabetes mellitus on subsequent cardiovascular outcomes and health service utilisation: a study protocol." BMJ Open 11, no. 2 (February 2021): e038775. http://dx.doi.org/10.1136/bmjopen-2020-038775.

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IntroductionHypertension (HT) and diabetes mellitus (DM) and are major disease burdens in all healthcare systems. Given their high impact on morbidity, premature death and direct medical costs, we need to optimise effectiveness and cost-effectiveness of primary care for patients with HT/DM. This study aims to find out the association of trajectories in disease patterns and treatment of patients with HT/DM including multimorbidity and continuity of care with disease outcomes and service utilisation over 10 years in order to identify better approaches to delivering primary care services.Methods and analysisA 10-year retrospective cohort study on a population-based primary care cohort of Chinese patients with documented doctor-diagnosed HT and/or DM, managed in the Hong Kong Hospital Authority (HA) public primary care clinics from 1 January 2006 to 31 December 2019. Data will be extracted from the HA Clinical Management System to identify trajectory patterns of patients with HT/DM. Complications defined by ICPC-2/International Classification of Diseases-Ninth Revision, Clinical Modification diagnosis codes, all-cause mortality rates and public service utilisation rates are included as independent variables. Changes in clinical parameters will be investigated using a growth mixture modelling analysis with standard quadratic trajectories. Dependent variables including effects of multimorbidity, measured by (1) disease count and (2) Charlson’s Comorbidity Index, and continuity of care, measured by the Usual Provide Continuity Index, on patient outcomes and health service utilisation will be investigated. Multivariable Cox proportional hazards regression will be conducted to estimate the effect of multimorbidity and continuity of care after stratification of patients into groups according to respective definitions.Ethics and disseminationThis study was approved by the institutional review board of the University of Hong Kong—the HA Hong Kong West Cluster, reference no: UW 19–329. The study findings will be disseminated through peer-reviewed publications and international conferences.Trial registration numberNCT04302974.
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6

Kovalyov, М. Ya, B. M. Rozin, and I. A. Shaternik. "Approach to optimizing charging infrastructure of autonomous trolleybuses for urban routes." Informatics 18, no. 4 (December 31, 2021): 79–95. http://dx.doi.org/10.37661/1816-0301-2021-18-4-79-95.

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P u r p o s e s. When designing a system of urban electric transport that charges while driving, including autonomous trolleybuses with batteries of increased capacity, it is important to optimize the charging infrastructure for a fleet of such vehicles. The charging infrastructure of the dedicated routes consists of overhead wire sections along the routes and stationary charging stations of a given type at the terminal stops of the routes. It is designed to ensure the movement of trolleybuses and restore the charge of their batteries, consumed in the sections of autonomous running.The aim of the study is to create models and methods for developing cost-effective solutions for charging infrastructure, ensuring the functioning of the autonomous trolleybus fleet, respecting a number of specific conditions. Conditions include ensuring a specified range of autonomous trolleybus running at a given rate of energy consumption on routes, a guaranteed service life of their batteries, as well as preventing the discharge of batteries below a critical level under various operating modes during their service life.M e t ho d s. Methods of set theory, graph theory and linear approximation are used.Re s u l t s. A mathematical model has been developed for the optimization problem of the charging infrastructure of the autonomous trolleybus fleet. The total reduced annual costs for the charging infrastructure are selected as the objective function. The model is formulated as a mathematical programming problem with a quadratic objective function and linear constraints.Co n c l u s i o n. To solve the formulated problem of mathematical programming, standard solvers such as IBM ILOG CPLEX can be used, as well as, taking into account its computational complexity, the heuristic method of "swarm of particles". The solution to the problem is to select the configuration of the location of the overhead wire sections on the routes and the durations of charging the trolleybuses at the terminal stops, which determine the corresponding number of stationary charging stations at these stops.
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7

Helfrich, Kathleen, and Donald F. Vitaliano. "Size and Cost Efficiency in the Production of Local Road Services." Public Works Management & Policy 3, no. 2 (October 1998): 124–32. http://dx.doi.org/10.1177/1087724x9800300203.

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The authors analyze 925 town highway departments in New York to determine potential economies from consolidation and the degree of cost efficiency. Only 15% of departments would reduce costs by merging, resulting in an average 13% reduction in expenditures. In addition, all of the towns are cost inefficient by an average 17%. Size economies are estimated using a log quadratic stochastic frontier regression model. The estimated cost curve is a textbook U shape with a mean cost elasticity of 0.97, indicating that most towns are operating at the minimum point of the curve. The composed error model is used to estimate cost inefficiency, which is not systematically linked to size inefficiency. However, 14 very small departments are quite cost inefficient.
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8

Lin, Ming-Hua, Jung-Fa Tsai, Yi-Chung Hu, and Tzu-Hsuan Su. "Optimal Allocation of Virtual Machines in Cloud Computing." Symmetry 10, no. 12 (December 15, 2018): 756. http://dx.doi.org/10.3390/sym10120756.

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Virtualization is one of the core technologies used in cloud computing to provide services on demand for end users over the Internet. Most current research allocates virtual machines to physical machines based on CPU utilization. However, for many applications that require communication between services running on different servers, communication costs influence the overall performance. Therefore, this study focuses on the optimal allocation of virtual machines across multiple geographically dispersed data centers, with the objective of minimizing communication costs. The original problem can be constructed as a quadratic assignment problem that is a classical NP-hard combinatorial optimization problem. This study adopts an efficient deterministic optimization approach to reformulate the original problem as a mixed-integer linear program that may be solved to obtain a globally optimal solution. Since the required bandwidth matrix and communication cost matrix are symmetric, the mathematical model of virtual machine placement can be simplified. Several numerical examples drawn from the literature are solved to demonstrate the computational efficiency of the proposed method for determining the optimal virtual machine allocation in cloud computing.
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9

Lin, Whei-Min, Chung-Yuen Yang, Ming-Tang Tsai, and Yun-Hai Wang. "Unit Commitment with Ancillary Services in a Day-Ahead Power Market." Applied Sciences 11, no. 12 (June 11, 2021): 5454. http://dx.doi.org/10.3390/app11125454.

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This paper integrates Discrete Particle Swarm Optimization (DPSO) and Sequential Quadratic Programming (SQP) to propose a DPSO-SQP method for solving unit commitment problems for ancillary services. Through analysis of ancillary services, including Automatic Generation Control (AGC), Real Spinning Reserve (RSR), and Supplemental Reserve (SR), the cost model of unit commitment was developed. With the requirements of energy balance, ancillary services, and operating constraints considered, DPSO-PSO was used to calculate the energy supply of each source, including the associated AGC, RSR, and SR, and the operating cost of a day-ahead power market was calculated. A study case using the real data from thermal units of Taipower Company (TPC) and Independent Power Producers (IPPs) demonstrated effective results for the “summer” and “non-summer” seasons, as classified by TPC for the two charging rates. According to the test cases in this research, costs without ancillary services in non-summer and summer seasons are higher than those with ancillary services. The simulation results are also compared with the Genetic Algorithm (GA), Evolutionary Programming (EP), Particle Swarm Optimization (PSO), and Simulated Annealing (SA). DPSO-PSO shows effectiveness in solving unit commitment problems with enhanced sorting efficiency, and a higher probability of reaching the global optimum.
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10

León-Quismondo, Jairo, José Bonal, Pablo Burillo, and Álvaro Fernández-Luna. "Walkability and Fitness Center Prices, Opening Hours, and Extra Services: The Case of Madrid, Spain." International Journal of Environmental Research and Public Health 17, no. 15 (August 4, 2020): 5622. http://dx.doi.org/10.3390/ijerph17155622.

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Walkability has been associated with urban development and political plans, contributing to more connected cities with improvements in communication, shopping, and pedestrian base. Among these services, fitness centers are becoming important elements for communities due to their impact on the health and welfare of citizens. The present study aims to examine how an area’s Walk Score® affects fitness center services, specifically membership costs, opening hours, and aquatic services. Data from 193 fitness centers were retrieved, representing all the areas of the municipality of Madrid, Spain, including fitness centers in the 21 city districts. A nonlinear relationship between an area’s Walk Score® and fitness centers’ monthly fees is observed. Only in premium fitness centers, a weak curvilinear model is observed, following a quadratic equation, showing that fitness centers with higher prices are in less walkable areas. Additionally, the association between Walk Score® and a fitness center’s opening hours reveals that fitness centers with wider hours of operation tend to be in moderately to highly walkable locations. Lastly, the existence of a swimming pool is related to a lower Walk Score®. Thus, fitness centers in less walkable areas try to offer additional services as differentiation from competitors, whereas centers in walkable locations use this advantage as a strength.
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Singla, Yaman Kumar, Sriram Krishna, Rajiv Ratn Shah, and Changyou Chen. "Using Sampling to Estimate and Improve Performance of Automated Scoring Systems with Guarantees." Proceedings of the AAAI Conference on Artificial Intelligence 36, no. 11 (June 28, 2022): 12835–43. http://dx.doi.org/10.1609/aaai.v36i11.21563.

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Automated Scoring (AS), the natural language processing task of scoring essays and speeches in an educational testing setting, is growing in popularity and being deployed across contexts from government examinations to companies providing language proficiency services. However, existing systems either forgo human raters entirely, thus harming the reliability of the test, or score every response by both human and machine thereby increasing costs. We target the spectrum of possible solutions in between, making use of both humans and machines to provide a higher quality test while keeping costs reasonable to democratize access to AS. In this work, we propose a combination of the existing paradigms, sampling responses to be scored by humans intelligently. We propose reward sampling and observe significant gains in accuracy (19.80% increase on average) and quadratic weighted kappa (QWK) (25.60% on average) with a relatively small human budget (30% samples) using our proposed sampling. The accuracy increase observed using standard random and importance sampling baselines are 8.6% and 12.2% respectively. Furthermore, we demonstrate the system's model agnostic nature by measuring its performance on a variety of models currently deployed in an AS setting as well as pseudo models. Finally, we propose an algorithm to estimate the accuracy/QWK with statistical guarantees (Our code is available at https://git.io/J1IOy).
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12

Tsvetkova, Antoaneta, and Silvia Mihaylova. "SOCIAL AND ECONOMIC ASPECTS OF THE INCREASING INCIDENCE OF DIABETES IN VARNA AND BULGARIA." Journal of IMAB - Annual Proceeding (Scientific Papers) 27, no. 3 (September 24, 2021): 3978–84. http://dx.doi.org/10.5272/jimab.2021273.3978.

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Objective: The impact of socio-economic factors on the increased incidence of chronic diseases requires changes in the policy of health authorities. In view of that, the study tried to investigate the role and consequences of those factors on T2DM and thus contribute to future development of comprehensive programmes for screening, diagnostics and treatment. Methods and materials: Forecasting the incidence rates of diabetes on a national and regional scale using regression analysis of results from municipal programs between 2015 and 2019 in Varna. The following models were studied: linear, cubic, quadratic, exponential, logarithmic, power, growth and inversion. Data processing and analysis were performed with the software set SPSS Statistics and graphical analysis with Microsoft Excel. Results: A constant rise in the number of diabetes cases was identified. At national level, mortality among females was higher than mortality in males, while at local level (Varna), such correlation was not established. Costs for the studied groups steadily increased during the studied period. Healthcare services for people with diabetes mellitus cost 2.5 times more than that of people without diabetes of the same age group.
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Drewitz, Nathaniel M., and David E. Stoltenberg. "Weed Communities in Strip-Tillage Corn/No-Tillage Soybean Rotation and Chisel-Plow Corn Systems after 10 Years of Variable Management." Weed Science 66, no. 5 (September 2018): 651–61. http://dx.doi.org/10.1017/wsc.2018.40.

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AbstractPrevious research has shown that strip-tillage (ST) systems conserve soil, reduce production costs, and save time for growers compared with intensive-tillage systems. In contrast to these well-documented benefits, we have limited information on weed community dynamics and management risks in ST corn (Zea maysL.) production systems in the northern Corn Belt. Therefore, we conducted research in 2015 and 2016 to characterize weed community composition, emergence patterns, and aboveground productivity in an ST corn/no-tillage (NT) soybean [Glycine max(L.) Merr.] rotation that was established in 2007 compared with a long-term intensive-tillage chisel-plow (CP) continuous-corn system. Fifteen or more weed species were identified in nontreated quadrats in each cropping system in each year. Common lambsquarters (Chenopodium albumL.) was the most abundant weed species across systems and years.Chenopodium albumdensities were similar between CP and ST corn phases and were approximately 2-fold greater compared with the NT soybean phase. Other abundant weed species occurred at much lower densities thanC. album. In each year, cumulative emergence of nontreated weed communities was described best by a logistic function in each cropping system. Maximum weed community emergence was greater in CP corn than ST corn phases in 2015, but did not differ in 2016. In the ST corn phase, most (about 75%) weed community emergence occurred in the in-row (tilled) zone compared with the between-row (nondisturbed) zone. Total late-season weed shoot biomass did not differ between nontreated CP and ST corn phases in either year, withC. albumaccounting for >85% of total weed biomass in these phases. These results suggest that weed community composition, total emergence, and productivity were similar between CP and ST corn phases after 10 yr. Our findings, coupled with previous research that showed favorable agronomic performance and greater soil conservation associated with the long-term ST corn/NT soybean system, suggest that production risks are no greater than a CP corn system, while processes that underpin ecosystem services are enhanced. These results provide strong evidence to support grower adoption of ST practices as an alternative to intensive tillage.
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14

Ouyang, Huiyin, Nilay Taník Argon, and Serhan Ziya. "Assigning Priorities (or Not) in Service Systems with Nonlinear Waiting Costs." Management Science, April 29, 2021. http://dx.doi.org/10.1287/mnsc.2020.3952.

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For a queueing system with multiple customer types differing in service-time distributions and waiting costs, it is well known that the cµ-rule is optimal if costs for waiting are incurred linearly with time. In this paper, we seek to identify policies that minimize the long-run average cost under nonlinear waiting cost functions within the set of fixed priority policies that only use the type identities of customers independently of the system state. For a single-server queueing system with Poisson arrivals and two or more customer types, we first show that some form of the cµ-rule holds with the caveat that the indices are complex, depending on the arrival rate, higher moments of service time, and proportions of customer types. Under quadratic cost functions, we provide a set of conditions that determine whether to give priority to one type over the other or not to give priority but serve them according to first-come, first-served (FCFS). These conditions lead to useful insights into when strict (and fixed) priority policies should be preferred over FCFS and when they should be avoided. For example, we find that, when traffic is heavy, service times are highly variable, and the customer types are not heterogenous, so then prioritizing one type over the other (especially a proportionally dominant type) would be worse than not assigning any priority. By means of a numerical study, we generate further insights into more specific conditions under which fixed priority policies can be considered as an alternative to FCFS. This paper was accepted by Baris Ata, stochastic models and simulation.
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Bravo, Fernanda, Cynthia Rudin, Yaron Shaposhnik, and Yuting Yuan. "Interpretable Prediction Rules for Congestion Risk in Intensive Care Units." Stochastic Systems, July 17, 2023. http://dx.doi.org/10.1287/stsy.2022.0018.

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We study the problem of predicting congestion risk in intensive care units (ICUs). Congestion is associated with poor service experience, high costs, and poor health outcomes. By predicting future congestion, decision makers can initiate preventive measures, such as rescheduling activities or increasing short-term capacity, to mitigate the effects of congestion. To this end, we consider well-established queueing models of ICUs and define “high-risk states” as system states that are likely to lead to congestion in the near future. We strive to formulate rules for determining whether a given system state is high risk. We design the rules to be interpretable (informally, easy to understand) for their practical appeal to stakeholders. We show that for simple Markovian queueing systems, such as the [Formula: see text] queue with multiple patient classes, our rules take the form of linear and quadratic functions on the state space. For more general queueing systems, we employ methods from queueing theory, simulation, and machine learning (ML) to devise interpretable prediction rules, and we demonstrate their effectiveness through an extensive computational study, which includes a large-scale ICU model validated using data. Our study shows that congestion risk can be effectively and transparently predicted using linear ML models and interpretable features engineered from the queueing model representation of the system. History: This paper has been accepted for the Service Science/Stochastic Systems Joint Special Issue. Supplemental Material: The online appendix is available at https://doi.org/10.1287/stsy.2022.0018 .
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Yin, Xiliang, Lin Ma, Ping Sun, and Xuezhi Tan. "A visual fingerprint update algorithm based on crowdsourced localization and deep learning for smart IoV." EURASIP Journal on Advances in Signal Processing 2021, no. 1 (September 20, 2021). http://dx.doi.org/10.1186/s13634-021-00795-7.

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AbstractRecently, deep learning and vision-based technologies have shown their great significance for the prospective development of smart Internet of Vehicle (IoV). When the smart vehicle enters the indoor parking of a shopping mall, the vision-based localization technology can provide reliable parking service. As known, the vision-based technique relies on a visual map without a change in the position of the reference object. Although, some researchers have proposed a few automatic visual fingerprinting (AVF) methods, which are aiming at reducing the cost of building the visual map database. However, the AVF method still costs too much under such a situation, since it is impossible to determine the specific location of the displaced object. Given the smart IoV and the development of deep learning approach, we propose an algorithm for solving the problem based on crowdsourcing and deep learning in this paper. Firstly, we propose a Region-based Fully Convolutional Network (R-FCN) based method with the feedback of crowdsourced images to locate the specific displaced object in the visual map database. Secondly, we propose a method based on quadratic programming (QP) for solving the translation vector of the displaced objects, which finally solves the problem of updating the visual map database. The simulation results show that our method can provide a higher detection sensitivity and correction accuracy as well as the relocation results. It means that our proposed algorithm outperforms the compared one, which is verified by both synthetic and real data simulation.
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Mirhoseyni, Seyed Valiallah, Ebrahim Bahraminia, and Mahdia Monsefi. "Economics of scale and optimal size of hospitals (case study of shahid Rahnemoun hospital)." International journal of health sciences, November 15, 2022, 48697–709. http://dx.doi.org/10.53730/ijhs.v6ns7.13651.

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Economies of scale are one of the important behavioral indicators of production units. In the presence of economies of scale, the scale curve is descending, which indicates a decrease in the average cost of production with an increase in production. Theoretically, the optimal size of a production unit is the volume of production at which the average cost is at its lowest. The issue of the need to pay attention to economies of scale and optimal allocation of resources on the one hand and the role and position of hospitals in providing medical services on the other hand and the high share of treatment costs in public spending in Iran, compared to the world average, The motivation was to evaluate the efficiency conditions in production and determine the optimal size of the hospital. In this study, in order to determine the optimal size of Shahid Rahnemoun Hospital in Yazd according to the number of beds, the cost quadratic function of the hospital translog was estimated based on production factors using the quadratic cost function method. The study period is 1390-1398, which uses Eviews econometric software.
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18

Tappeiner, John, Darius Adams, Claire Montgomery, and Douglas Maguire. "Growth of Managed Older Douglas-fir Stands: Implications of the Black Rock Thinning Trial in the Coast Range of Western Oregon." Journal of Forestry, December 13, 2021. http://dx.doi.org/10.1093/jofore/fvab063.

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Abstract The most recent remeasurement of growth (at approximate total stand age 100 years) from the Black Rock Thinning Trial in western Oregon provides useful information for forest owners interested in accelerating restoration of older forest characteristics in Douglas-fir stands of the Pacific Northwest. Thinnings at several intensities at total stand age of roughly 50 years effectively reset stand growth patterns. With quadratic mean diameters in thinned plots up to 40% higher than those of unthinned controls, thinned plot mean annual increments (MAIs) and periodic annual increments continue to rise 55 years after thinning, with the peak in board foot and cubic foot MAI apparently still decades in the future. Assuming repeatable future thinning responses similar to the Black Rock Trial, financial analysis of the opportunity costs of extending rotations to 100 years indicates that some thinning treatments can reduce opportunity costs by up to half at a 6% discount rate. Study Implications Active management through thinning may be a useful tool for public and private landowners interested in rapid development of stands with older forest characteristics to enhance output of some ecosystem services. Heavy thinning regimes, of the type described here, are compatible with growing trees with large diameter stems, large branches, and large crowns. They also reduce fuel accumulation by lowering mortality rates of stems less than 60 years old and slowing the rate of crown recession, branch mortality, and branch litterfall. Midrotation thinning revenues reduce opportunity costs of holding more rapidly growing stems to older ages, which may be a consideration for some owners.
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19

Owa, Adebayo F., Fisayo Adesina, and Olawale O. Ajibola. "Computer Aided Modelling of the Impact of Irregular Power Supply on Machining Foundry Products." FUOYE Journal of Engineering and Technology 5, no. 2 (September 20, 2020). http://dx.doi.org/10.46792/fuoyejet.v5i2.493.

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Computer aided models such as Dynamic, Quadratic, and Integer programming have been developed to solve production challenges relating to Manpower, Inventory and Maintenance assuming constant and regular power supply, which is a hard condition to meet in a developing country like Nigeria where power supply is irregular. This paper developed a Computer aided model to address this challenge using Integer programming (IP), by considering profit (Z) as a function of cost and revenue of a machined foundry product. Software was developed to serve as database and the same time analyzed complex mixed – model system where parallel workstation, shift or batch production is allowed. The software was designed to have graphic user interface (GUI), which enable the user to input data like values of product code (identification number for each product), capacity of machine, established unit cost of production, production cycle time, selling cost and the unit cost of production to determine the impact when electricity power from national grid is used, as opposed to fueling a diesel-engine generator, for machining foundry products. Costs and production capacity data were collected from Ruthade Foundry Engineering Services, Akure, Ondo State, to validate the model. The results revealed that output per unit time is higher when power from national grid is holistically utilized than when power from generator was used for machining foundry product. The results serve as genuine guiding tool for foundry operators in selecting a particular course of action on electricity utilization during production and enhance sustainability of production industry. Keywords— Constraint, cycle time, integer programming, Microsoft Visual Basic, model, optimal number
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20

Nakashima, Manabu. "Performance information use in a purpose-oriented network: A relational perspective." Journal of Public Administration Research and Theory, September 19, 2022. http://dx.doi.org/10.1093/jopart/muac039.

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Abstract Performance information use is an essential component of performance management, which is an important tool to manage purpose-oriented networks (PONs). Conceptualizing performance information use in PONs as network members’ presentation, discussion, and interpretation of performance information during their interactions and communication, this study explores its drivers. Extant studies on performance information use in PONs point out an association between its use and the relationships among network members, but they lack specificity regarding the association. This study focuses on and theorizes that association, relying on network theory (especially the embeddedness approach) and resource dependence theory. Network analysis techniques (Multiple Regression Quadratic Assignment Procedure and Exponential Random Graph Modeling) are applied to investigate the theory empirically, using a pair (dyad) of network members as the unit of analysis. The data were collected from 21 members in a health and human services network serving children and youth with serious emotional disturbance in a U.S. county. Two types of performance information were used in the PON: internally and externally produced information. Despite differences in the breadth and decision-making relevance of using information from these two sources, network analyses identify three relational characteristics consistently associated with the dyads’ use of internal and external performance information: (1) frequency of communication; (2) centrality of position; and (3) extent of mutual dependency. These findings suggest that network members are likely to use performance information in relationships where the benefits of developing a shared understanding of network performance outweigh the costs of using it.
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