Performance Calculation Model Research Articles

Implementation of Road Performance Calculation Models Used in Strategic Planning Systems for Lithuania Conditions

Deficiency or inadequate allocation of road maintenance and development funds leads to total road network degradation. In order to ensure proper condition of road pavement with a limited budget, we need road maintenance optimisation for the entire road network. The road maintenance optimisation can be achieved using knowledge-based strategic planning systems. The collection and analysis of necessary data help design different road maintenance long-term strategies. The output results help select priorities for road maintenance and proper fund allocation. Optimal road maintenance strategy is the way to keep a fairly good road network with available funds. In addition, the road user costs can be reduced. The aim of this paper is to offer a road maintenance management system for Lithuanian conditions. The model will help evaluate the performance of the current road network and prepare a multi-year priority list for road works.

Analysis on energy saving and thermal insulation performance of improved straw brick in northern cold area

In order to improve the air pollution caused by farmers’ treatment of crop by-products in the cold north, the energy saving and thermal insulation properties of improved straw brick buildings are studied. Firstly, the main process of building a house with straw brick and improved straw brick made of straw stalk is introduced, and a thermal performance calculation model based on the heat exchange principle of the wall is built. Then, the thermal load performance test parameters of ordinary brick and improved straw brick are introduced. Finally, the thermal load calculation results of ordinary brick and improved straw brick are compared and analyzed. The results show that in terms of economic efficiency, compared with ordinary brick, straw brick house not only has a wide range of sources but also has simple process of production, so it has a better economic efficiency; in terms of environmental protection, the production of straw brick houses, compared with ordinary bricks, will not emit emissions and is an environmentally friendly raw material; in terms of energy consumption, the insulation of straw brick can well regulate the indoor and outdoor environment and effectively reduce the heat loss. This study provides a good theoretical basis for popularizing the use of improved straw bricks.

Proposal and thermodynamic performance study of a novel LNG-fueled SOFC-HAT-CCHP system with near-zero CO2 emissions

The cold energy in many liquefied natural gas (LNG) satellite stations is directly carried away by air or seawater. This causes cold energy waste and environmental cold pollution. To solve this problem, a combined power, heating and cooling system (CCHP) driven by LNG is established based on solid oxide fuel cell (SOFC) and humid air turbine (HAT), namely SOFC-HAT-CCHP system, in which, not only can the waste cold energy cool compressor inlet air to decrease power consumption, but supply cold energy for the cold storage and CO2 recovery. Based on FORTRAN and Aspen Plus, the thermodynamic performance calculation models and the simulation work of the new system are carried out, such as the exergy and energy analysis, as well as the effects of the selected important variables. The results indicate that total exergy efficiency and total power efficiency are 64.7% and 54.4%, and the total thermal efficiency is 79.1%. Besides, the capture rate and purity of the CO2 are 98.7% and 98.9% respectively. The novel system is environmental protective, energy-saving and efficient, which may provide a new direction to reasonably utilize the waste cold energy in LNG satellite stations.

Forecasting method of electric vehicle load time-space distribution considering traffic distribution

The main work of this paper is to establish an electric vehicle(EV) load forecasting model based on road network traffic distribution for urban and inter-city transportation networks. This paper established a road network model considering the traffic impedance for the EV load forecasting of the urban fast charging network, and studied the prediction method of the time-space distribution of EV charging demand in the fast charging mode .Based on the expressway, the method for predicting the time-space distribution of EV load in the inter-city fast charging network is studied, and a time-space distribution load forecasting model is established. Based on the time-space distribution of traffic flow, combined with EV charging characteristics and travel routes, load simulation is performed. By constructing a prediction method for the time-space distribution of EV charging demand in the fast charging mode, it provides theoretical and methodological support for the research of time-sharing and segmented metering and charging strategies for EV fast charging stations,, and provides an important reference for the development of EV charging facilities operating cost benefits, economic performance indicators and calculation models under fast charging mode, which are of great significance to promote the popularization and application of EV fast charging modes.

Thermodynamic Design and Performance Calculation of the Thermochemical Reformers

Thermodynamic design methods and performance calculation models for chemical reformers that can be used to recuperate exhaust heat and to improve combustion quality are investigated in this paper. The basic structure of the chemical reformer is defined as series-wound reforming units that consist of heat exchangers and cracking reactors. The CH4-steam reforming reaction is used in the chemical reformers and a universal model of this reaction is built based on the minimization of Gibbs free energy method. Comparative analyzes between the results of the calculation and a plasma-catalyzed CH4-steam reforming reaction experiment verify that this universal model is applicable and has high precision. Algorithms for simulation of series-wound reforming units are constructed and the complexity of the chemical reformers is studied. A design principle that shows the influence of structural complexity on the quantity of recovered heat and the composites of the reformed fuel can be followed for different application scenarios of chemical reformers.

Thermodynamic performance study of the SOFC-STIG distributed energy system fueled by LNG with CO2 recovery

The SOFC-STIG distributed energy system is a significant developing trend in the field of energy technology. The SOFC-STIG distributed energy system fueled by LNG with CO2 recovery is put forward in this paper. In the new system, the LNG's cold energy can not only supply cold energy, but also cool compressor inlet air to reduce consumption of compressor work and recovery liquid CO2. Based on each part's mathematical model, the new system's thermodynamic performance calculation model is built by FORTRAN. And with the help of the simulation tool ASPEN Plus, the simulation work was carried out at steady state using Peng-Robinson equation of state. The results of calculation indicate that the thermal efficiency and the power efficiency of this distributed energy system are 72.77% and 57.08% while the exergy efficiency can reach 61.9%. Furthermore, several important variables including fuel flow rate, steam injection ratio and fuel utilization factor are selected to analyze the system performance.

Compression performance and bearing capacity calculation model of small-eccentricity columns strengthened with textile-reinforced mortar (TRM)

To study the compression performance of TRM-strengthened columns with small eccentricities, a total of 9 reinforced concrete (RC) columns with end corbels were subjected to compression testing. The test parameters are as follows: the number of textile layers, the ratio of longitudinal reinforcement, and polyvinyl alcohol (PVA) short-cut fiber volume fraction. The experimental results indicated that, compared to the control, columns with three layers of textile exhibited an approximately 10.66% increase in the bearing capacity. However, the effect increased only slightly when the number of textile layers increased to 4. Besides, the effect was improved with the increase in the ratio of longitudinal reinforcement and PVA fiber volume fraction. Finally, based on laboratory tests and related research results, a model for calculating normal section bearing capacity of TRM-strengthened columns with small eccentricities was presented. A comparison of the theoretical and experimental data demonstrated the applicability of the proposed model.

RESEARCH OF THE MAGNETOELECTRIC LINEAR OSCILLATORY MOTOR CHARACTERISTICS DURING OPERATION ON ELASTOVISCOUS LOADING

Purpose. To development of mathematical model for calculation of the magnetoelectric linear vibration motor performance with elastoviscous loading and research of machine characteristics in the different operational modes depending on loading parameters. Methodology. Experimental results by means of the developed test setup according to the specified methods are obtained. Moreover we have correlated the experimental data obtained by means of the development experimental setup with the simulated results using analytical model of the linear oscillatory motor with elastoviscous loading. In the analytical model of the linear vibration motor a one-mass vibration system with equivalent parameters of stiffness and viscous friction is considered. Results. Calculations of performance data for three operating modes of the oscillatory motor - for constant value of current, constant amplitude and acceleration of vibrations are carried out. Results of calculation by means of analytical model are coordinated with the experimental data obtained with help of a prototype of the linear motor and the load machine. Originality . Analytical expressions for performance data of the linear vibration motor which are based on the analytical model and an equivalent circuit with the lumped parameters are obtained. It is shown that for calculation of performance data depending on parameters of loading it is possible to use analytical model which is based on an equivalent circuit with constant inertial parameters of the linear motor. Practical value. Results of the work can be used for designing new and improvements of the existing vibration devices on the basis of linear motors with the specified performance data.

Validated ejector model for hybrid system applications

The aim of this work is the presentation of a new model for ejector performance calculation using a commercial tool. Due to the critical issues in recirculation performance, special attention is devoted to applications in hybrid systems based on high temperature fuel cells. The theoretical activity is supported by an experimental rig able to operate tests on ejectors at different operative conditions, with a layout similar to the fuel cell anodic recirculation. The model validation, operated considering experimental data obtained with this rig, is essential to evaluate the tool performance for design and off-design calculations. This aspect is particularly critical due to important limitations in the recirculation ratio (especially for the anodic side), to avoid unacceptable operative conditions in the fuel cells.The results presented in this work were obtained with this validated model for an ejector applied on the anodic side of a Solid Oxide Fuel Cell (SOFC). A parametric analysis was carried out to show the effects of several parameters on the recirculation performance. The fully independent analysis of the influence of different properties (carried out with a specifically validated model) is an important innovative result for the application of such ejectors on high temperature fuel cells.

Analytical Electromagnetic Performance Calculation of Vernier Hybrid Permanent Magnet Machine

The analytical model of vernier hybrid permanent magnet machines (VHPMMs) with two different permanent magnet (PM) arrays is proposed in this paper. The working principles of VHPMM are discussed based on the magnetic field modulation theory, and the main rotating harmonics of air-gap flux density are determined. The subdomain method is adopted to obtain the no-load and on-load air-gap flux densities of the slotless model, and the relative permeance model is used to consider the effect of the slot opening. Using fast Fourier transformation, the amplitudes and phase angles of the rotating harmonics are obtained, and the flux linkage, back electromotive force, and electromagnetic torque are calculated. With the working principles and performance calculation model, the determination method of the rotor slot number is proposed, and feasible combinations of PM and rotor slot numbers are studied. The analytical model is verified via the finite-element method and prototype machine experiments.

A general performance calculation model of journal bearing using unified coordinate system

PurposeBecause of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This paper aims to simplify the calculation of the journal bearing performance, and to reduce the workload.Design/methodology/approachOn the basis of previous research, a general performance calculation model of journal bearing is proposed in this paper. Eccentricity ratio and attitude angle of axis to each pad are calculated by coordinates of spindle center and each pad center by establishing the unified coordinate system. The surface deformation of journal bearing is taken into consideration, and a correction value is added to the dimensionless oil film thickness.FindingsThe performance calculation results of various fix-pad and tilting-pad journal bearings match the results of the existing references very well, revealing the validity of the model. The general model can greatly reduce programming workload, and increase adaptability to different bearings.Originality/valueGeometric descriptions of both fix-pad and tilting-pad journal bearings are unified in this model, which can be applied to both standard and non-standard journal bearings with different preload ratios. In addition, due to the unification of different bearings types, this model is more conducive to performance comparison among different bearing types, and promotes the development of new structural forms for journal bearings.

Energy performance of buildings: A statistical approach to marry calculated demand and measured consumption

In public debate, Energy Performance Certificates (EPCs) of buildings have been criticised for not reflecting the energy demand realistically. And indeed, measurement, as in energy bills, usually differs from the calculation, in particular, when simplified energy performance calculation models and standard specifications are applied, as in EPCs. Thus, energy-saving potentials of refurbishment recommendations and their cost-effectiveness tend to be over-estimated. Of course, this is not desirable. These effects were analysed in two sets of data, the Energy Performance Certificate Register for residential buildings in Luxemburg, run by the Luxemburg Ministry of the Economy (Lichtmes, 2012) and a database gathered in the research project “Teilenergiekennwerte von Nichtwohngebauden (TEK)” (Horner et al., 2014a) funded by the German Federal Ministry of Economic Affairs and Energy. Multiple linear regression and error calculus were applied to study the gap between measurement and various calculation models in detail. A statistical procedure is proposed to estimate expectation value and variance of the future energy consumption of buildings in case of refurbishment, as a supplement to standard calculations in EPCs for example. Prerequisite is that for a sufficient number of buildings, data on both, measured energy consumption and calculated demand, are available.

An Approximate Solution of Muijderman's Model for Performance Calculation of Spiral Grooved Gas Seal

This paper presents an approximate solution of Muijderman's model for compressible spiral grooved gas film. The approximate solution is derived from Muijderman's equations by Adomian decomposition method. The obtained approximate solution expresses the gas film pressure as a function of the gas film radius. The traditional Runge–Kutta method is avoided. The accuracy of the approximate solution is acceptable, and it brings convenience for performance calculation of spiral grooved gas seal. A complete Adomian decomposition procedure of Muijderman's equations is presented. The approximate solution is validated with published results.

Heliostat field layout methodology in central receiver systems based on efficiency-related distribution

This paper deals with a methodology for heliostat field layout. The methodology, described and validated herein, includes a detailed calculation model for the heliostat field’s mean annual optical efficiency covering the factors of cosine efficiency, shading and blocking efficiency, mirror reflectivity, atmospheric attenuation and receiver interception efficiency. Certain measures are taken to reduce the time consumption for the calculation of the shading and blocking efficiency. On the basis of the performance calculation model the field generation methodology, in which the heliostat field is generated by means of adding the heliostats to the field in sequence, is proposed. This new methodology does not yet perform a grand optimization and it currently depends on the running of other codes to determine optimum tower height and receiver dimensions. In this described methodology, the annually equivalent efficiency distribution (AEED), in pursuit of the maximization of the field’s efficiency, is first proposed and calculated as the basis of positioning the heliostats. Not only the shadowing and blocking effects of the existing heliostats, but also the effects of the heliostats added to the existing heliostats are considered in AEED. The newly added heliostat should be positioned on the best position of the updated AEED so that the average efficiency of the existent heliostats including that new heliostat reaches a maximum. The PS10 field is rearranged by using the AEED-based method and the result shows that the rearranged field improves the original PS10 field by 0.57% in the mean annual optical efficiency and 1.19% in the insolation unweighted efficiency. Furthermore, on the basis of the above method, the cost is taken into account and the efficiency/cost ratio distribution (ECRD) is then used for field generation. The rearrangement result suggests that ECRD-based field has substantially reduced the land area of AEED-based field and shown a good performance in the levelized energy cost.

Effects for console game sales in Japan market

Purpose – The purpose of this paper is to examine the respective effects of advertising, word of mouth (operationalized as “tweets” on Twitter), and serialization on sales of console game series in Japan. Design/methodology/approach – To do this, the author classified console game series into four categories on the basis of their sales, identified a singular case that corresponds to each category, and presented a performance calculation model that approximates variation in sales for the first and second titles of each series. Findings – Coupled with the results generated by the performance models a comparison of each game series showed that although word-of-mouth and backward serialization may influence sales performance for the first title in a console game series, sales of the second title in the series were most heavily influenced by forward serialization and advertising. The author further found that word-of-mouth via social networks was unlikely to affect the sales performance of a series’ second title. Research limitations/implications – The sales of first title video game console series permit the forecasting and evaluation of the sales’ second title performance through the performance calculation model incorporating the advertising, word-of-mouth, and serialization effect and vice versa. Originality/value – Taken together, these results demonstrate that the affordances of social networking can be used to improve sales performance for the first title in a series, and the use of backward serialization for subsequent titles could incite the purchase of over a million copies of the game(s).

Unified coordinate system model for performance calculation of fix-pad journal bearing with different pad preload

Traditional model for calculating performance parameters of a fix-pad journal bearing leads to heavy workload, complicated and changeable formulae as it requires deriving various geometric formulae with different bearing types such as circular journal bearing, dislocated bearing and elliptic bearing. Considering different pad preload ratios for non-standard bearing, traditional model not only becomes more complicated but also reduces scalability and promotion of the calculation programs. For the complexly case of traditional model while dealing with various fix-pad journal bearings, unified coordinate system model for performance calculation of fix-pad journal bearing is presented in the paper. A unified coordinate system with the bearing center at the origin is established, and the eccentricity ratio and attitude angle of axis relative to each pad are calculated through the coordinates of journal center and each pad center. Geometric description of fix-pad journal bearing is unified in this model, which can be used for both various standard bearing and non-standard bearing with different pad preload ratios. Validity of this model is verified with an elliptical bearing. Performance of a non-standard four-leaf bearing with different pad preload ratios is calculated based on this model. The calculation result shows that increasing preload ratio of the pad 1 and keeping that of the left three pads constant improves bearing capacity, stiffness and damping coefficients. This research presents a unified coordinate system model unifies performance calculation of fix-pad journal bearings and studied a non-standard four-leaf bearing with different pad preload ratios, the research conclusions provides new methods for performance calculation of fix-pad journal bearings.

Materials-to-System Analysis for Grid-Based Electrochemical Energy Storage: Lithium-Polysulfide Hybrid Flow Battery

Energy storage systems are crucial for extensive deployment of renewable energy such as solar and wind systems and huge demand on the electrical grid to recharge electric vehicles. Scalable energy storage with low cost and high energy density will be a key to meet these challenges [1]. Lithium-polysulfide (Li-PS) flow batteries are of particular interest due to their scalability, high potential chemistries, and potentially low cost for grid storage applications [2].Here we present a materials-to-system analysis of the Li-PS flow battery by using techno-economic model which combines electrochemical performance and cost calculation model to examine feasibility for grid storage application. In the system, lithium polysulfide in ether-based solvent and metallic lithium are used as the catholyte and anolyte, respectively [3]. The model examines the correlation between performance and cost as considering the physical property limitations of the system components, Figure 1. Additionally, the consequences on cost and energy density from change in system properties such as redox material concentration, potential, and specific capacity are assessed to probe design phase space for the requirements of an application.Figure 1. Summary flow of the techno-economic model Acknowledgments This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

Multicondition Optimization and Experimental Measurements of a Double-Blade Centrifugal Pump Impeller

In order to improve internal unsteady flow in a double-blade centrifugal pump (DBCP), this study used major geometric parameters of the original design as the initial values, heads at three conditions (i.e., 80% design flow rate, 100% design flow rate, and 120% design flow rate) as the constraints conditions, and the maximum of weighted average efficiency at the three conditions as the objective function. An adaptive simulated annealing algorithm was selected to solve the energy performance calculation model and the supertransitive approximation method was applied to fix optimal weight factors of individual objectives. On the basis of hydraulic performance optimization, three-condition automatic computational fluid dynamics (CFD) optimization of impeller meridional plane for the DBCP was realized by means of Isight software integrated Pro/E, Gambit, and Fluent software. The shroud arc radii R0 and R1, shroud angle T1, hub arc radius R2, and hub angle T2 on the meridional plane were selected as the design variables and the maximum of weighted average hydraulic efficiency at the three conditions was chosen as the objective function. Performance characteristic test and particle image velocimetry (PIV) measurements of internal flow in the DBCP were conducted. Performance characteristic test results show that the weighted average efficiency of the impeller after the three-condition optimization has increased by 1.46% than that of original design. PIV measurements results show that vortex or recirculation phenomena in the impeller are distinctly improved under the three conditions.

Development of highly effective cryogenic printed circuit heat exchanger (PCHE) with low axial conduction

This paper presents the results of an experimental investigation of the thermal and hydraulic performance of a printed circuit heat exchanger (PCHE) for use in the cryogenic temperature region. Compact PCHEs with multiple corrugated, longitudinal flow microchannels were fabricated using chemical etching and diffusion bonding to evaluate their thermal and hydraulic performance. The testing of the PCHEs was conducted with helium gas at cryogenic temperatures. The pressure drop and thermal effectiveness values obtained from the measured pressures and temperatures are discussed. The thermal performance was predominantly affected by the axial conduction heat transfer in the low Reynolds number ranges of theses experiments. A simple performance calculation model is presented, and the effectiveness calculated from the model is compared with the experimental data. The design of the cryogenic PCHE was then modified to reduce axial conduction losses.

Determining suitable execution environment based on dynamic workload during early stages of software development life cycle: a simulation approach

In the early development stages of distributed software systems, assessing performance and corresponding prediction techniques remains an important but largely unsolved problem. In the distributed environment, the workload and the deployment environment of the software components have major impact on the performance and they are uncertain. The problem of uncertainty regarding performance requirement data is required to be addressed by estimation techniques. Hence, in this paper we present a mathematical model for performance calculation and simulate the model that supports a decision maker involved in performance analysis for a given distributed application. We analyse the execution environment by considering various configurations of hardware resources based on dynamic workload over a time horizon. The methodology is demonstrated through a case study and the results are validated. Results show that the proposed methodology is useful in identifying suitable execution environment corresponding to the defined performance goal. The bottleneck resources are identified and suggestions for improvement are given.