•Modelling patient flows, important for performance improvement of hospital processes.•Existing approaches for patient flow modelling in hospital systems are classified.•Recent literature on patient ...flow modelling and performance analysis is reviewed.•A generic framework for such modelling and analysis of hospital systems is provided.•The framework may serve as a guide to improve healthcare delivery.
Analysis of hospital processes is essential for development of improved methods, policies and decision tools for overall performance improvement of the hospital system. Amidst the current scenario of continuously increasing healthcare costs and scarcity of resources, optimal utilization of resources without hampering the quality of care has gained importance in any country. Modelling, analysis and management of patient flows, in this context, plays a key role in performance analysis and improvement of hospital processes as appropriate modelling of patient flows may help healthcare managers make decisions related to capacity planning, resource allocation and scheduling, appointment scheduling and for making necessary changes in the process of care. The concept of patient flow and its modelling has gained much attention in healthcare management literature over past few decades. In this paper, the existing approaches pertaining to modelling of patient flows in hospital systems have been classified and critically appraised focussing on the recent advancements in order to identify future research avenues. A generic framework for patient flow modelling and performance analysis of hospital systems that may serve as a guide for the practitioners dealing with similar kinds of problems to improve healthcare delivery has also been provided.
In this paper, we compare measured, modelled, and simulated mean velocity profiles. Smooth pipe flow simulations are performed for both incompressible (below Mach 0.2) and compressible (below Mach ...0.1) fluids. The compressible simulations align most closely with the measurements. The simulations are subsequently used to make scaling formulae of the turbulence intensity as a function of the Reynolds number. These scaling expressions are compared to scaling derived from measurements. Finally, the found compressible scaling laws are used as an example to show how the flow noise in a flowmeter is expected to scale with the mean flow velocity.
•We compare measured, modelled and simulated mean velocity profiles.•Incompressible and compressible simulations are performed and compared to modelling and measurements.•Scaling expressions for the turbulence intensity as a function of the Reynolds number are derived using both simulations and measurements.
In this paper a detailed method for fault detection of an in-core three wires Resistance Temperature Detectors (RTD) sensor is introduced. The method is mainly based on the dependence of the fuel rod ...temperature profile on control rods elevation and coolant flow rate in a given nuclear reactor. For the implementation, an artificial neural network (ANN) technique has been developed to model the dynamic behaviour of the considered temperature sensor. In order to have more refined model estimation, ANN has been combined with additional noise reduction algorithms. The effective denoising work was done via the discrete wavelet transform (DWT) to remove various kinds of artefacts such as inherent measurement noise. The principle of the adopted fault detection task is based on the calculation of the difference between the ANN model estimated temperature and the online being measured temperature and then compare the deviation with a certain detection threshold to decide the sensor fault. The efficiency of the method is evaluated first on a simulated case and then on the on-line measurements obtained from a real plant. Results confirm the capacity of the developed ANN-based model to estimate a fuel rod temperature with a reasonable accuracy.
•A new method for on-line fault detection of a fuel rod temperature measurement sensor in a nuclear reactor core is introduced.•Results confirm the ability of the developed ANN-based model to estimate a fuel rod temperature.•The methodology can be generalized for large scale temperature sensor plants.•The suggested method does not require any physical knowledge of the processes.
In literature, numerous models are available to predict Global Solar Radiation (GSR) on a horizontal surface, which is predominantly a site-specific characteristic. Hence, a comparative study is ...required to predict GSR using a correct model for a particular site. The principal aim of the present work is to analyze the most precise model for estimation of monthly average daily global solar radiation (MADGSR) on a horizontal surface for the region of interest. In the current work, the performance of 300 existing sunshine based GSR models are compared using 15-year meteorological data for Tropical wet and dry climatic region of India. The accuracy of each model is tested using ten different statistical error tests. Further, the Global Performance Indicator (GPI) is used to rank the selected GSR models. According to results, the Ampratwum Model (Model 274, proposed for Marmul, Oman) has shown the best capability to estimate the GSR on a horizontal surface followed by Srivastava (Model 26, proposed for Kolkata, India) and Rensheng model (Model 282, proposed for China). The results of the present study are valuable for the developing countries and remote areas where very few metrological stations are available since the technological expenses are very high.
•Solar radiation measurements are obtained for Tropical Wet & Dry Climatic Region.•Monthly-average global solar radiation is estimated using empirical models.•Models relating clearness index with sunshine duration ratio are considered.•Accuracy of the models is evaluated in terms of several statistical parameters.•Models are ranked for suitability of estimation using Global Performance Indicator.
Summary
Proton‐exchange‐membrane fuel cells (PEMFCs) are a popular source of alternative energy because of their operational reliability and compactness. This paper presents an improved model to ...represent the semi‐empirical voltage of PEMFCs to overcome the limitations of existing models. The proposed model considers variations in ambient conditions, such as the ambient temperature and relative humidity, to obtain the accurate output voltage that corresponds to variations in dynamic and static loads. The proposed model was developed by conducting several experiments on the Horizon PEMFC system under normal, humid, and dry ambient conditions. Subsequently, the model parameters corresponding to each case were optimised using the quantum lightning search algorithm (QLSA). Parameters demonstrating significant variations with ambient conditions were finally represented as a function of the ambient temperature and relative humidity via statistical regression analysis. The voltage obtained using the modified model was verified by conducting experiments on both the Horizon and NEXA PEMFC systems by varying the ambient temperature and relative humidity with root mean square error (RMSE) less than 0.5. As observed, the results we obtained using the modified model closely approximated those obtained using PEMFCs under various operating conditions, and in both cases, the PEMFC voltage was observed to vary with the ambient and load conditions. The inherent advantages of the proposed PEMFC model include its ability to determine the membrane‐water content and water pressure inside PEMFCs. The membrane‐water content provides clear indications regarding the occurrence of drying and flooding faults. Under normal conditions, this membrane water content ranges from 11 to 7 for both the Horizon and NEXA PEMFC system. The simulation results suggested using the threshold membrane‐water‐content level as a possible indicator of fault occurrence under extreme ambient conditions. The limits of the said threshold were observed to be useful for fault diagnosis within PEMFC systems.
The management of suspended solids and associated contaminants in rivers requires knowledge of sediment sources. In-situ sampling can only describe the integrated impact of the upstream sources. ...Empirical models that use surface reflectance from satellite images to estimate total suspended solid (TSS) concentrations can be used to supplement measurements and provide spatially continuous maps. However, there are few examples, especially in narrow, shallow and hydrologically dynamic rivers found in mountainous areas. A case study of the Didipio catchment in Philippines was used to address these issues. Four 5-m resolution RapidEye images, from between the years 2014 and 2016, and near-simultaneous ground measurements of TSS concentrations were used to develop a power law model that approximates the relationship between TSS and reflectance for each of four spectral bands. A second dataset using two 2-m resolution Pleiades-1A and a third using a 6-m resolution SPOT-6 image along with ground-based measurements, were consistent with the model when using the red band data. Using that model, encompassing data from all three datasets, gave an R2 value of 65% and a root mean square error of 519mgL−1. A linear relationship between reflectance and TSS exists from 1mgL−1 to approximately 500mgL−1. In contrast, for TSS measurements between 500mgL−1 and 3580mgL−1 reflectance increases at a generally lower and more variable rate. The results were not sensitive to changing the pixel location within the vicinity of the ground sampling location. The model was used to generate a continuous map of TSS concentration within the catchment. Further ground-based measurements including TSS concentrations that are higher than 3580mgL−1 would allow the model to be developed and applied more confidently over the full relevant range of TSS.
Display omitted
•Applicability of VHR satellite images in suspended solids monitoring in 4–10m wide rivers•Empirical modelling between surface reflectance and total suspended solids (TSS)•Investigation of inter-station and inter-year variations of pixel reflectance values•Investigation of spectral bands that accurately represent TSS in shallow mountain rivers•Calibration of a satellite image into a thematic map of TSS
Aims/hypothesis
The objective was to investigate if metformin pharmacokinetics is modulated by time-of-day in humans using empirical and mechanistic pharmacokinetic modelling techniques on a large ...clinical dataset. This study also aimed to generate and test hypotheses on the underlying mechanisms, including evidence for chronotype-dependent interindividual differences in metformin plasma and efficacy-related tissue concentrations.
Methods
A large clinical dataset consisting of individual metformin plasma and urine measurements was analysed using a newly developed empirical pharmacokinetic model. Causes of daily variation of metformin pharmacokinetics and interindividual variability were further investigated by a literature-informed mechanistic modelling analysis.
Results
A significant effect of time-of-day on metformin pharmacokinetics was found. Daily rhythms of gastrointestinal, hepatic and renal processes are described in the literature, possibly affecting drug pharmacokinetics. Observed metformin plasma levels were best described by a combination of a rhythm in GFR, renal plasma flow (RPF) and organic cation transporter (OCT) 2 activity. Furthermore, the large interindividual differences in measured metformin concentrations were best explained by individual chronotypes affecting metformin clearance, with impact on plasma and tissue concentrations that may have implications for metformin efficacy.
Conclusions/interpretation
Metformin’s pharmacology significantly depends on time-of-day in humans, determined with the help of empirical and mechanistic pharmacokinetic modelling, and rhythmic GFR, RPF and OCT2 were found to govern intraday variation. Interindividual variation was found to be partly dependent on individual chronotype, suggesting diurnal preference as an interesting, but so-far underappreciated, topic with regard to future personalised chronomodulated therapy in people with type 2 diabetes.
Graphical abstract
세계화의 진전에 따라 도시는 더 이상 어느 국가의 민족적 경계 내의 장소만은 아니다.
이제 도시는 민족적, 지역적, 세계적 차원이 공존하는 장소가 되어가고 있다. 오늘날 전 세계인구의 반 이상이 대도시에 살고 있으며, 이들 도시는 국가를 초월해 세계 경제성장의 원동력이 되어가고 있다. 또한 이들 도시는 단순히 한 국가의 경계에 머무는 것이 아니라, 자신의 ...장소를 국제화하고 자국내뿐 아니라 전 세계에 있는 다른 도시들과 국제적 경쟁을 한다.
이에 전 세계 도시를 지표화해서 비교하고 도시간의 연결성을 살펴보는 작업의 필요성이 대두된다. 이러한 배경하에 본 연구에서는 도시의 국제화 정도를 평가하기 위한 계량 모형 이른바 ‘글로벌지수’를 구축하고자 한다. ‘글로벌지수’ 개발에 있어 본 연구는 우선 도시국제화비교를 위한 국제화 계수를 개발하고 계량모형을 구축하였다. 그리고 국가별-연도별 패널데이터를 활용하여 ‘글로벌지수’ 계량모형의 타당성을 검토하였다. 이러한 검토작업을 통해 표준화된 도시 국제화 비교를 위한 ‘부산글로벌지수’의 필요변수와 구성요인을 정리하였다. 요컨대 본 연구는 도시국제화 비교를 위한 국제화 계수를 개발하고 계량모형을 구축함으로써부산의 국제화 정도를 알기 위한 개략적인 방향을 제시함과 동시에 기타 도시들과 비교할 수있는 표준화된 모형을 시론적으로 제시한 것에 그 목적이 있다. With the advancement of globalization, cities are no longer just places within the ethnic boundaries of a country. Cities are now becoming places where national, regional, and global dimensions coexist. More than half of the world’s population lives in large cities, and these cities are transcending countries. They act as a driving force of global economic growth. Accordingly, the research first presents an econometric model to construct a global index. We conduct a series of empirical modeling to calculate the coefficients necessary for the model and build a global index with relative objectiveness. After building a global index with series of quantitative modelling, we conduct a country- and year-level comparison among countries. Lastly we suggest future plans and necessary variables for creating a global index by city particularly for Busan. We suggest some necessary and significant variables that could be extracted both from the existing database and from series of survey. The main purpose of the research is to present a rough direction of constructing Busan global index which is significant for international comparison among cities. The research aims to give fundamental insights to the significance of constructing city-level global index, and furthermore, basic idea of constructing the index using necessary variables. Our research contributes to the past and current literature reltaed to the global index by presenting a robust index from series of empirical modeling and coefficients which could be adopted as a global index to compare global cities. KCI Citation Count: 0
Empirical Modelling of Acoustic Emission Impulses Vera, Barat; Vladimir, Bardakov; Artem, Marchenkov
International journal of innovative technology and exploring engineering,
10/2019, Letnik:
8, Številka:
12
Journal Article
Odprti dostop
emission nondestructive testing method is very widespread diagnostic method based on phenomena of radiation of acoustic waves during the materials destruction. The main advantages of the method are ...sensitivity to the crack and possibility of remote testing when sensor installed far from the defect. The main drawback of the method is complexity of data processing. Acoustic emission signals are characterized by the variability of the shape and spectrum associated with the dispersive nature of the propagation of the signal along the waveguide. Uncertainty of the signal waveform and spectrum complicates the development of the data processing methods. The article proposes an empirical model of the acoustic emission impulse constructed using generalization of experimental data. The use of this model makes it possible to increase the efficiency of noise filtering by comparing the shape and spectrum of acoustic emission impulses and noise at various distances between the defect and the sensor.
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