Values Of Key Parameters Research Articles

Towards a Metrology class ADC based on Josephson junction devices

Precision measurement of DC and AC voltages requires an analogue to digital converter specification to have two key parameter values: the number of effective or noise free bits and the signal bandwidth. Commercial ADCs may offer the potential for use in a metrology class voltmeter but there is no easy way to compare the dynamic specification of a DMM with that of an ADC, especially when the number of bits or bandwidth changes. An architecture independent ADC/DMM figure of merit (FOM), is proposed to facilitate this comparison. At National Measurement Institutes, it is necessary to be able to measure with significantly greater precision than the device or instrument under test. Analysis shows that the FOM required of a metrology class ADC is beyond the state of the art for both ADCs and instruments. Fortunately, the use of superconducting Josephson junction based circuits offers the possibility to achieve the required precision. This paper gives the background to and reviews the progress of an EU funded research project for a quantum analogue to digital converter which is aiming to achieve the required FOM, beyond the state of the art.

Performance-based contract design under cost uncertainty: A scenario-based bilevel programming approach

ABSTRACTThis article considers a principal agent model for structuring a performance-based contract in the presence of fixed cost and cost-plus contracts. A scenario-based bilevel programming approach is considered to determine the values of key contract parameters. Additionally, the risk of cost uncertainty is considered in the model in the form of conditional value at risk (CVaR). The incorporation of risk of cost uncertainty can mitigate the impact of extreme events in the tail of the customer's total cost distribution. The numerical results find that at higher risk aversion levels, the customer is willing to pay more to the supplier and at the same time accept a smaller percentage of the shared cost between the supplier and the customer, which indicates the shift of the risk to the supplier. Although the customer is paying more in higher risk aversion levels, less cost is incurred in cases of realization of extreme events compared to the lower risk aversion levels. At lower risk aversion levels, the customer sets a smaller value of incentives for the supplier.

Cost-effectiveness analysis of guideline-based optimal care for venous leg ulcers in Australia

BackgroundVenous leg ulcers (VLUs) are expensive to treat and impair quality of life of affected individuals. Although improved healing and reduced recurrence rates have been observed following the introduction of evidence-based guidelines, a significant evidence-practice gap exists. Compression is the recommended first-line therapy for treatment of VLUs but unlike many other developed countries, the Australian health system does not subsidise compression therapy. The objective of this study is to estimate the cost-effectiveness of guideline-based care for VLUs that includes public sector reimbursement for compression therapy for affected individuals in Australia.MethodsA Markov model was designed to simulate the progression of VLU for patients receiving guideline-based optimal prevention and treatment, with reimbursement for compression therapy, and then compared to usual care in each State and Territory in Australia. Model inputs were derived from published literature, expert opinion, and government documents. The primary outcomes were changes to costs and health outcomes from a decision to implement guideline-based optimal care compared with the continuation of usual care. Sensitivity analyses were performed to test the robustness of model results.ResultsGuideline-based optimal care incurred lower total costs and improved quality of life of patients in all States and Territories in Australia regardless of the health service provider. We estimated that providing compression therapy products to affected individuals would cost the health system an additional AUD 270 million over 5 years but would result in cost savings of about AUD 1.4 billion to the health system over the same period. An evaluation of unfavourable values for key model parameters revealed a wide margin of confidence to support the findings.ConclusionsThis study shows that guideline-based optimal care would be a cost-effective and cost-saving strategy to manage VLUs in Australia. Results from this study support wider adoption of guideline-based care for VLUs and the reimbursement of compression therapy. Other countries that face similar issues may benefit from investing in guideline-based wound care.

Projections of progress toward the 80% Bachelor of Science in Nursing recommendation and strategies to accelerate change

BackgroundIn 2011, the Institute of Medicine recommended that 80% of RNs have a bachelor's degree or higher by 2020. Progress toward this recommendation has been slow. PurposeThis paper presents a model that projects whether the 80% recommendation can be met within a 10-year period and estimates the impact of education changes that might accelerate progress. MethodsA projection model for 2016 to 2026 was created using a “stock-and-flow” approach. Secondary data were extracted from multiple sources for the projections. The model includes the option to enter alternative values of key parameters to estimate the impact of changes. DiscussionBased on current patterns of entry-level and RN-to-BSN education, approximately 66% of RNs are projected to have BSN+ education by 2025. ConclusionsTo reach the 80% goal by 2025, changes in the mix of entry-level education and/or an increase in the number of RN-to-BSN graduates will be required.

Homogenized and pore-scale analyses of forced convection through open cell foams

Open cell foams have desirable geometrical characteristics that make them a suitable choice in various heat exchanger applications. The objective of this study is to determine such volume-averaged key parameters that can characterize the complex thermal transportation process through open cell foams. These key parameters are represented by effective thermal conductivity, ke, volumetric heat transfer coefficient, hv, and dispersion conductivity, kd. In order to determine these parameters, detailed pore-scale simulations through the representative element volumes (REVs) of the actual foam structures are performed. Moreover, knowing the fact that the successful implementation of simplified foam structures as a suitable representative of the actual foam structures can simplify the complexity of the problem, it is also investigated. In the presented work, various microscopic pore-scale models are implemented for both simplified and actual foam structures to determine the key parameters. Subsequently, these key parameters are implemented into two different homogenized macroscopic models to predict the temperature fields of large-scale steady-state and transient forced convection processes. The numerical outcomes of homogenized macroscopic models are validated with the experimental data, which is available for a set of ceramic foams having different pore size (10–30 PPI) and porosity (79–87%). As a consequence of the validation process, the findings of this study reveal that the proposed methodology successfully predicts the values of the concerned key parameters. Further, it is observed that simplified foam structures cannot represent the actual foam structures, as the tortuous shape of open cell foams bound to enhance the advection and dissipation of heat due to recirculation and eddy formation.

How do learning externalities influence the evaluation of Ontario's renewables support policies?

Support programs for renewable electricity generation in Ontario have been in place since 2005, including feed-in-tariffs and a competitive procurement process. These programs have been criticized on a number of fronts. In particular, critics claim the level of support was excessive and creating surplus supply. However, prior studies have ignored one potential benefit of renewable energy support—that it can help to promote cost reductions in new technologies through learning-by-doing.This paper uses a recursive-dynamic computable general equilibrium (CGE) model featuring learning-by-doing effects to assess the renewable support programs provided in Ontario. Our results, in line with previous studies, do not justify the high support rates paid in Ontario given our core range of assumptions. But our modeling approach allows us to identify the combination of key parameter values relating to learning effects and environmental damages that justify the observed rates. These parameters are hard to measure empirically, and our modeling approach introduces a new tool for examining the impact of variations in these parameters on policy analysis.

Long-term terrestrial carbon dynamics in the Midwestern United States during 1850-2015: Roles of land use and cover change and agricultural management.

To meet the increasing food and biofuel demand, the Midwestern United States has become one of the most intensively human-disturbed hotspots, characterized by widespread cropland expansion and various management practices. However, the role of human activities in the carbon (C) cycling across managed landscape remains far from certain. In this study, based on state- and national census, field experiments, and model simulation, we comprehensively examined long-term carbon storage change in response to land use and cover change (LUCC) and agricultural management in the Midwest from 1850 to 2015. We also quantified estimation uncertainties related to key parameter values. Model estimation showed LUCC led to a reduction of 1.35Pg (with a range of 1.3-1.4Pg) in vegetation C pool of the Midwest, yet agricultural management barely affected vegetation C change. In comparison, LUCC reduced SOC by 4.5Pg (3.1 to 6.2Pg), while agricultural management practices increased SOC stock by 0.9Pg. Moreover, we found 45% of the study area was characterized by continuously decreasing SOC caused by LUCC, and SOC in 13% and 31% of the area was fully and partially recovered, respectively, since 1850. Agricultural management was estimated to increase the area of full recovery and partial recovery by 8.5% and 1.1%. Our results imply that LUCC plays an essential role in regional C balance, and more importantly, sustainable land management can be beneficial for strengthening C sequestration of the agroecosystems in the Midwestern US, which may serve as an important contributor to C sinks in the US.

MODELS AND MECHANISMS TO IMPROVE THE COMPETITIVENESS OF A HIGHER EDUCATION INSTITUTION

The aim of the research is to improve the efficiency of decision making for increasable of the competitiveness of the university. The article proposes a mechanism for assessing the competitiveness of a higher educational institution in the market of educational services on the basis of simulation modeling. A system of indicators of the activity of a higher educational institution is proposed. The choice of factors for the development of the model was carried out in accordance with the Pareto principle: the parameters that have the greatest impact on the competitiveness of the university are taken into account. A cognitive map of the situation that determines the mutual influence of factors is constructed. A simulation model based on the integration of the principles of system dynamics and cognitive modeling, which allows you to manage the values of key parameters, is developed. The values of the variables in the model can be changed while determining the sensitivity of the vector of the output parameters. Using a method based on specifying control points, a scale of characteristics has been developed for each factor. The possibility of evaluating alternative scenarios and predicting the possible consequences of management decisions based on them is shown. The model based on real data is presented. The main stages of the algorithm for determining competitiveness are as follows: determination of the purpose of the evaluation; determination of the types of activities that are taken into account in the analysis; selection of the reference database; definition of characteristics to be measured; evaluation of selected characteristics; calculation of the generalized, integral indicator of competitiveness; conclusions about competitiveness. As can be seen from the algorithm, the effectiveness of assessing the competitive position of an organization depends on the choice of characteristics, the determination of their relative importance (weight in the overall estimate, %) and the evaluation of these characteristics for the university and its main competitors. To analyze the mutual influence of the competitiveness factors of the university, it is proposed to use a simulation model that combines the principles of system dynamics and cognitive modeling. The choice of development methodologies is determined by the fact that a simulation model is an effective tool for modeling dynamic controlled systems with a high level of abstraction and a multitude of feedbacks. The cognitive approach makes it possible to synchronize changes in parameter values and analyze the influence of model parameters on each other. For the development of the model, the AnyLogic system was selected, combining the possibilities of creating hybrid models based on models of system dynamics, discrete-event models, and the agent approach. The state of the system under investigation can be described using classical approaches of system theory, in particular, cognitive modeling. The cognitive model of a complex, weakly structured system and is represented by a functional graph whose vertices are the main factors (concepts), and the arcs are the connections of the mutual influence of factors on each other. The model of the influence of factors of the university competitiveness on each other is a dynamic system that is determined by a set of parameters and a set of direct and inverse relations between them.

INFLUENCE OF TEMPERATURE-DEPENDENT CONDUCTIVITY ON CONVECTIVE HEAT TRANSFER IN A VERTICAL DUCT

An analysis has been carried out to study the flow and heat characteristics of a Newtonian fluid in a vertical rectangular duct. One of the vertical walls of the duct is cooled to a constant temperature, while the other wall is heated to constant but different temperature. The thermal conductivity is assumed to vary as a linear function of temperature. The basic equations governing the flow and heat transfer are highly non-linear coupled partial differential equations. Numerical solution of the problem is obtained by using finite difference method of second-order accuracy. The effects of various physical parameters such as conductivity parameter BK (-1 ≤ BK ≤ 1.0), Grashof number Gr (1.0 ≤ Gr ≤ 25.0), Brinkman number Br (0.01 ≤ Br ≤ 2.0), and aspect ratio A(0.5 ≤ A ≤ 2.0), which determine the velocity and temperature contours, are shown pictorially. Results are also presented for the skin friction, volumetric flow rate, and heat transfer rate for representative values of different key parameters. It is found that the intensity of the velocity contours is dense in the lower half region of the duct for negative values of conductivity variation parameter and in the upper region of the duct for positive values of conductivity variation parameter. The 3D contours on temperature are concave for negative values of BK and convex for positive values of BK.

Evaluation of Three Wheat Species (Triticum aestivum L., T. spelta L., T. dicoccum (Schrank) Schuebl) Commonly Used in Organic Cropping Systems, Considering Selected Parameters of Technological Quality

A recent interest in the usage of different wheat species for organically grown healthy food has led to resurgence in cultivation not only of hulled wheat, but also of coloured-grain wheat, which contains a large number of nutrients that have vital importance for human feed. The study was aimed to determine and compare the technological properties of Triticum spelta L., Triticum dicoccum (Schrank) Schuebl and colouredgrain wheat (Triticum aestivum L.). The research was based on field experiment carried out at the Agronomy experimental station of National University of Life and Environmental Sciences of Ukraine (Kyiv region) during the period 2014-2016. The data were analyzed using ANOVA method. The difference of weather conditions among experimental years did not have significant influence on examined parameters. On the other hand quality parameters significantly depended on the wheat species. The results obtained indicated that the highest protein content was testified in emmer wheat 20.8 %, but the highest wet gluten yield (30.8 %) and as a result better rheological dough properties was determined in spelt wheat. Significantly the least values for such key parameters as flour strength (W), water absorption, sedimentation value were found examining T. aestivum (coloured). Overall it should be noted that all three examined wheat species had poor technological properties for bread producing in most characteristics, except protein content.

Optimization of AEB Key Parameters in Car to Electric-Two-Wheeler Accidents

In order to determine the optimal value of key parameters of automatic emergency braking (AEB) system, an optimization method based on real accident simulation is proposed. Accident reconstruction of 65 car to electric-two-wheeler collision accidents was carried out by using PC-Crash. According to the different parameter values of AEB system radar, the virtual accident reconstruction results are obtained. The optimal value of key AEB parameters was determined by comparing the accident avoidance rate. The results show that: based on these 65 real rear end collisions, the final optimization results of the radar detection angle and detection distance in the AEB system are 90° and 120 m respectively.

Socio‐Economic Interest of Treated Wastewater Reuse in Agricultural Irrigation and Indirect Potable Water Reuse: Clermont‐Ferrand and Cannes Case Studies' Cost–Benefit Analysis

AbstractUnlike many structuring projects, treated wastewater reuse projects are rarely subjected to economic analysis. And when they are, the social and environmental benefits and costs are often not accounted for or are not properly quantified. Here we show that the widely used cost–benefit analysis method showing the profitability of a project from the whole of the community's point of view can be adapted to treated wastewater reuse projects. The remaining evaluation difficulties are more due to the system's complexity rather than its methodological limits. Indeed, the operator must be able to understand, formalize and imagine constraints and risks associated with different domains such as urbanism, agriculture, climate, hydrology and trade. Remaining uncertainties over key parameter values can, however, be properly considered through scenarios and/or stochastic approaches. We illustrate the implementation of this methodological approach with two case studies: Clermont‐Ferrand where treated wastewater is reused by a collective irrigation network; and Cannes where surface and groundwater recharge can enable indirect reuse for multiple purposes including indirect potable water production. These two French case studies highlight how economic analysis, dealing with uncertainties, can support decision making. Copyright © 2020 John Wiley & Sons, Ltd.

Optimal online channel strategies for a hotel considering direct booking and cooperation with an online travel agent

AbstractThis paper studies the channel strategies for a hotel considering alternative online distribution channels. The decision for the hotel involves whether to rely on direct booking via its official website or cooperating with an online travel agent (OTA), and if the latter is suggested, what business model to be adopted for the cooperation with the OTA. Three mathematical models, i.e., direct booking model, OTA merchant model, and OTA agent model, are developed to evaluate the costs and benefits in the three different cases. The negotiation process in the OTA agent model is studied by using the generalized Nash bargaining solution. The optimal decisions and profits are analyzed with respect to the values of key parameters. Results of numerical examples are discussed to show the implications of the established models.

Comment on “High resolution coherence analysis between planetary and climate oscillations”

The paper by Scafetta entitled “High resolution coherence analysis between planetary and climate oscillations”, May 2016 claims coherence between planetary movements and the global temperature anomaly. The claim is based on data analysis using the canonical covariance analysis (CCA) estimator for the magnitude squared coherence (MSC). It assumes a model with a predetermined number of sinusoids for the climate data. The results are highly dependent on this prior assumption, and may therefore be criticized for being based on the opposite of a null hypothesis.More importantly, since values of key parameters in the CCA method are not given, some experiments have been performed using the software of the original authors of the CCA estimator. The purpose was to replicate the results of Scafetta using what was perceived to be the most probable parameter values. Despite best efforts, this was not possible.

Display Light Guide Swelling Due to Moisture Absorption

Display light guides, commonly constructed of a polymer such as polymethyl methacrylate (PMMA), are known to be susceptible to moisture absorption, swelling, and warping in the field when exposed to elevated ambient humidity levels. This work presents a quantitative theoretical framework for calculating water absorption over time. In addition, a simple theory is laid out, which connects mass absorption of water to linear expansion of the polymer. Finally, a simple quantitative analysis of out-of-plane warping of the light guide is presented. Experimental data from laboratory PMMA coupons and two different sizes of large displays are used to establish the values of key parameters of the theoretical model. General purpose results for any size of PMMA display are presented. The approach can easily be adapted to light guides fabricated using other polymers.

Parametric characteristics and optimum criteria of a near-field solar thermophotovoltaic system at the maximum efficiency

The model of a near-field solar thermophotovoltaic system (NF-STPVS) consisting of a solar concentrator, an absorber, an emitter, an optical filter, and a photovoltaic (PV) cell is proposed, in which the near-field radiation between the emitter and the PV cell, the radiation and reflection losses from the absorber to the environment, and the finite-rate heat transfer between the PV cell and the heat sink are taken into account. By using the fluctuational electrodynamics and irreversible thermodynamics, formulas for the power output and efficiency of the system are analytically derived. By solving energy balance equations, the operating temperatures of the emitter and the PV cell are calculated for given values of the output voltage of the PV cell and the vacuum gap. The concentration factor at the maximum efficiency of the system is optimally given. Furthermore, the maximum efficiencies of the system are calculated for two cases of the absence and presence of the Auger recombination and the corresponding optimum values of several key parameters are determined.

SIMULATION OF HIGHER EDUCATIONAL ESTABLISHMENT COMPETITIVENESS

The success of International Joint Educational Programs of the Educational Establishments based on effective management. This makes a need for predicting the competitiveness indicators in order to analyze different strategies for the expansion of higher education establishments and the picking up the best scenarios of its market play. The simulation methodology makes possible to performe analysis management that contains elements of actions that influenced by random factors. Using the method of system dynamics as the main tool is due to the complexity of the strategic alternatives selection in a dynamically developing situation, under conditions of external and internal uncertainty. The initial state of performed simulation was based on the parameters that define the market share and the number of potential students of the joint educational program between Admiral Makarov National University of Shipbuilding and partner in Zhejiang City, China. Sensitivity analysis experiments allow determining the influence of the initial hypotheses and the key parameters values on the model output parameters of the interference of competitiveness factors under uncertainty conditions. This significantly improves the effectiveness of management processes.

Natural Convection and Entropy Generation in a Square Cavity with Variable Temperature Side Walls Filled with a Nanofluid: Buongiorno’s Mathematical Model

Natural convection heat transfer combined with entropy generation in a square cavity filled with a nanofluid under the effect of variable temperature distribution along left vertical wall has been studied numerically. Governing equations formulated in dimensionless non-primitive variables with corresponding boundary conditions taking into account the Brownian diffusion and thermophoresis effects have been solved by finite difference method. Distribution of streamlines, isotherms, local entropy generation as well as Nusselt number has been obtained for different values of key parameters. It has been found that a growth of the amplitude of the temperature distribution along the left wall and an increase of the wave number lead to an increase in the average entropy generation. While an increase in abovementioned parameters for low Rayleigh number illustrates a decrease in average Bejan number.

Modelling the demand for new nitrogen fixation by terrestrial ecosystems

Abstract. Continual input of reactive nitrogen (N) is required to support the natural turnover of N in terrestrial ecosystems. This N demand can be satisfied in various ways, including biological N fixation (BNF) (the dominant pathway under natural conditions), lightning-induced abiotic N fixation, N uptake from sedimentary substrates, and N deposition from natural and anthropogenic sources. We estimated the global new N fixation demand (NNF), i.e. the total new N input required to sustain net primary production (NPP) in non-agricultural terrestrial ecosystems regardless of its origin, using a N-enabled global dynamic vegetation model (DyN-LPJ). DyN-LPJ does not explicitly simulate BNF; rather, it estimates total NNF using a mass balance criterion and assumes that this demand is met from one source or another. The model was run in steady state and then in transient mode driven by recent changes in CO2 concentration and climate. A range of values for key stoichiometric parameters was considered, based on recently published analyses. Modelled NPP and C : N ratios of litter and soil organic matter were consistent with independent estimates. Modelled geographic patterns of ecosystem NNF were similar to other analyses, but actual estimated values exceeded recent estimates of global BNF. The results were sensitive to a few key parameters: the fraction of litter carbon respired to CO2 during decomposition and plant-type-specific C : N ratios of litter and soil. The modelled annual NNF increased by about 15 % during the course of the transient run, mainly due to increasing CO2 concentration. The model did not overestimate recent terrestrial carbon uptake, suggesting that the increase in NNF demand has so far been met. Rising CO2 is further increasing the NNF demand, while the future capacity of N sources to support this is unknown.

GFETSIM: Graphene Field-Effect Transistor Simulator of Interface Charge Density

The discovery of graphene by Andre Geim and Konstantin Novoselov in 2004 contributed significantly to complementary metal-oxide-semiconductor (CMOS) technology, especially for electronic devices. Due to its outstanding properties, graphene has been used in many applications such as field-effect transistors (FETs), touch-sensitive screens, liquid-crystal displays, light-emitting diodes, dye-sensitised solar cells, and organic solar cells. Consequently, interface charge density in graphene field-effect transistors has become an important area of research in order to more accurately determine electronic characteristics such as capacitance-voltage (C-V). In this research, we developed a comprehensive simulation tool based on graphene FET called graphene field-effect transistor simulator (GFETSIM) of interface charge density, which functions as a graphical user interface (GUI) using MATLAB. This simulation represents the on-going development of a carbon-based device simulator begun in 2014 at Universiti Teknologi Malaysia (UTM). An automated selfconsistent approach is utilised to extract and compute the interface charge density. It is coded in MATLAB and the program was developed into an interactive MATLAB GUI simulation tool. The interface for GFETSIM is generated using the graphical user interface development environment (GUIDE) in MATLAB. This simulator allows users to import external C-V data into the GUI and carry out analysis based on the density of states plots. In addition, key parameter values can be varied to assess the outcome and changes in interface trapped density. In addition, a reset button is embedded into the simulator.