Proposed Performance Criteria Research Articles

Using mechanistic–empirical based analysis to evaluate rutting performance thresholds for balanced mix design tests

The balanced mix design (BMD) framework uses laboratory test methods to establish specifications that would ultimately be used for the design and acceptance of asphalt mixtures. Assembling such specifications is vital to optimizing the performance of asphalt mixtures for the distress of concern without violating any other criteria, consequently establishing the much desired “balance.” This research presents a stepwise method towards the establishment of performance test threshold criteria for rutting evaluation only as part of a greater effort that the Virginia Department of Transportation (VDOT) is pursuing for the implementation of the BMD framework. Data and discussion of five performance tests addressing rutting performance, along with six representative Virginia mixtures, are presented. AASHTOWare Pavement ME analyses at the material level and project level were utilized to fine-tune observations obtained using the surrogate test methods for rutting evaluation. Potential routes and accompanying challenges towards establishing/refining performance criteria that would prove helpful to the ultimate adoption of BMD specifications were outlined. An example of proposed performance criteria based on the presented data is provided. The proposed performance thresholds for rutting evaluation are intended as indicative; for full development and implementation, further refinement of the values is warranted.

Inverse dynamic estimates of muscle recruitment and joint contact forces are more realistic when minimizing muscle activity rather than metabolic energy or contact forces

BackgroundAssessment of contact forces is essential for a better understanding of mechanical factors affecting progression of osteoarthritis. Since contact forces cannot be measured non-invasively, computer simulations are often used to assess joint loading. Contact forces are to a large extent determined by muscle forces. These muscle forces are computed using optimization techniques that solve the muscle redundancy problem by assuming that muscles are coordinated in a way that optimizes performance (e.g., minimizes muscle activity or metabolic energy). However, it is unclear which of the many proposed performance criteria best describes muscle coordination. Research questionWhich performance criterion best describes muscle recruitment patterns and knee contact forces recorded using electromyography (EMG) and load cell instrumented prostheses?. MethodsWe solved the muscle redundancy problem based on six different groups of performance criteria: muscle activations, volume-scaled activations, forces, stresses, metabolic energy, and joint contact forces. Computed muscle excitations and knee contact forces during over-ground walking were validated against recorded EMG signals and measured contact forces for four subjects with instrumented knee prostheses in the “Grand Challenge Competition to Predict in Vivo Knee Loads” dataset. ResultsPerformance criteria based on either stress or muscle activation (either unscaled or scaled by muscle volume), both to a power of 3 or 4, resulted in the best agreement between measured and simulated values. These performance criteria outperformed all other criteria in terms of agreement between simulated muscle excitations and EMG, whereas good agreement between measured and predicted contact forces was also observed for minimization of contact forces and metabolic energy. SignificanceGiven the large differences in accuracy obtained with different performance criteria (e.g., root mean square errors of contact forces differed up to 0.45 body weight), the results of our study are important to improve the validity of in silico assessment of joint loading.

A contemporary vision of project success criteria

Goal: The objective of this research is to provide researchers and project management professionals with a contemporary view of the measurement of project success.
 Design/Methodology/Approach: After a dense literature review, a research-based study analyzes the project success criteria perspectives of 264 Brazilian project managers and provides a ranking of the most widely used measures in practice in Brazilian organizations.
 Results: The study analyzes contemporary literature on project success criteria and discusses overlaps and trends. One of the important findings of this research is the identification of mismatches between academic perspectives and those of project managers in regard to project success as well as real success criteria used in organizations. 
 Limitations of the investigation: As the sample covered was comprised exclusively of Brazilian project managers, cross-cultural success criteria research is, therefore, encouraged.
 Practical implications: The proposed performance criteria can be used in future research and for professional proposes in success criteria assessment.
 Originality/Value: Given the diversity of success criteria measures, authors can have difficulty in finding the one that better fits their needs; alternatively, they can create their own scale. The reliability of several studies can be questioned due to their subjectivity and, in some cases, weakly defined measures. The present study can therefore provide project professionals with guidelines for success assessment that make measuring and comparing different projects possible.

Fractional order modeling and control of dissimilar redundant actuating system used in large passenger aircraft

In this paper, a methodology has been developed to address the issue of force fighting and to achieve precise position tracking of control surface driven by two dissimilar actuators. The nonlinear dynamics of both actuators are first approximated as fractional order models. Based on the identified models, three fractional order controllers are proposed for the whole system. Two Fractional Order PID (FOPID) controllers are dedicated to improving transient response and are designed in a position feedback configuration. In order to synchronize the actuator dynamics, a third fractional order PI controller is designed, which feeds the force compensation signal in position feedback loop of both actuators. Nelder-Mead (N-M) optimization technique is employed in order to optimally tune controller parameters based on the proposed performance criteria. To test the proposed controllers according to real flight condition, an external disturbance of higher amplitude that acts as airload is applied directly on the control surface. In addition, a disturbance signal function of system states is applied to check the robustness of proposed controller. Simulation results on nonlinear system model validated the performance of the proposed scheme as compared to optimal PID and high gain PID controllers.

Compound identification using random projection for gas chromatography–mass spectrometry data

In general, compound identification through library searching is performed on original mass spectral space by using some developed similarity measure. More powerful similarity measure need more computational time. In order to reduce computational time, the original mass spectral space was transformed into binary space by random projection. The hamming distance between query and reference the vector of binary space are calculated. In this study, Mass Spectral Library 2005 (NIST05) main library containing 163,195 mass spectra is used as reference database. The replicate library containing 23,290 mass spectra is used as query data. The proposed method was used to compare with existing five similarity measures. Among two proposed performance criteria, composite semi-partial similarity measure achieve the best identification accuracy, then follow the random projection. When the binary number of random projection set as 2176 bits, the identification accuracy of rank 1 reach to 83.1%. If only considering computational time, random projection is the most rapid approach among five algorithms. Therefore, random projection can be also used as a filter to create searching sub-library for other complicated similarity measures. A series experiments are conducted by using random projection filter, the experimental results show the computational time of other similarity measure is reduced and the identification performance is not sacrificed.

Estimating flow data in urban drainage using partial least squares regression

Flow monitoring in wastewater systems is used for system operation or for billing purposes, among others. Given the difficult measurement conditions, gaps in measurement series occur frequently and stakeholders need an appropriate method to estimate missing data. In data scarcity situations, mathematical modelling of the underlying physical processes may not be feasible and other methods are required. Partial least squares (PLS) regression is a multivariate statistical method suited to correlated data and has been frequently used for water quality estimates. PLS suitability for hourly and daily flow estimations was tested, based on previous flow and precipitation data, which urban water utilities currently monitor. Results were evaluated using proposed performance criteria and classes. The estimation errors were comparable to the ones obtained in physical process modelling. The application of the proposed method for flow estimation in sewers, in two common scenarios of wet and dry weather flows, is presented and discussed.

MARGIN AND EFFICIENCY OF FORMING OF WIRE DEPENDING ON THE ANGLE OF DRAWING

Results of calculation of the axial stress, the absolute margin of safety, safety I.L. Perlin factor for wire were determined and the authors proposed criteria for evaluating the effectiveness of forming at drawing round solid profi le. At the optimum value of the angle of drawing, when the axial stress is minimal, can be observed maximum values of the safety factor and the proposed performance criteria of forming.

Optomechanical scanning systems for microstereolithography (MSL): Analysis and experimental verification

Optomechanical scanning systems with focused laser spot are used in several applications including microstereolithography (MSL), scanning optical tweezers, and laser cutting. Systems used so far in the literature for scanning a focused laser spot on a substrate are: (a) galvanomirror preobjective scanning, (b) galvanomirror postobjective scanning and (c) ‘off-axis’ lens scanning system (originally proposed by coauthors). Major performance criteria due to end application, (say for example, to obtain high resolution microdevices in MSL) translates into the following criteria on optical scanning system: (i) uniform spot size and (ii) uniform intensity profile over the entire range of scan. This paper presents comparative optical analysis, both theoretical and experimental, of these systems based on the proposed performance criteria. Optical analysis of the optomechanical scanning systems is carried out by using geometric ray tracing method. Image evaluation in this case is done using diffraction wave optics. Simulations are carried out to determine spot characteristics at image plane when scan distances are changed by moving optics in the above mentioned optomechanical scanning systems. Simulation and experimental results clearly show that there is lesser distortion of spot characteristics (size and intensity profile) in case of proposed off-axis lens scanning system as compared to other systems over wider scan range. Hence this system is more promising to fabricate high resolution micro-components and in general for other similar applications as well.

Space-vector PWM techniques for dual three-phase AC machine: analysis, performance evaluation, and DSP implementation

The major drawback of dual three-phase ac machines (6phiM), when supplied by a voltage-source inverter (VSI), is the occurrence of extra harmonic currents. These extra currents circulate only in the stator windings and cause additional losses. One solution to reduce their amplitude is to act on the supply side using dedicated pulsewidth modulation (PWM) control strategies. The aim of this paper is to investigate new space-vector PWM (SVPWM) techniques suitable for 6phiM and to perform a detailed analysis and a performance evaluation. The proposed performance criteria, specific to VSI-fed 6phiM, lead to analytical formulas and graphics, which aid the design of high-performance PWM techniques and demonstrate the superiority of the proposed SVPWM techniques. Experimental results carried out on a 15-kW prototype machine and using a low-cost fixed-point TMS320F240 digital signal processor are given and discussed

MEASURING FLOW THROUGH SMALL WASTEWATER TREATMENT WORKS USING MODIFIED DOSING SYPHONS

ABSTRACTThe Environment Agency have proposed that daily flow volume discharged from small wastewater treatment works should be capable of being measured to an accuracy of ±8%, where the daily totalised flow volume is estimated to be greater than 5m3. It is estimated that every water company in the UK has several hundred small wastewater treatment works that will be required to be equipped with the capability of measuring the released daily totalised flow volume for specified periods. This paper investigates the feasibility of modifying existing dosing syphons, which are present within many of these works, to operate as flow measuring devices. Laboratory testing of a full‐scale syphon demonstrated that by the addition of two water level detectors and a data logger to monitor the filling part of the syphon cycle, it is possible to accurately calculate the daily totalised flow volume within the Environment Agency’s proposed performance criteria.

Performance evaluation and optimization of human control strategy

Modeling human control strategy (HCS) is becoming an increasingly popular paradigm in a number of different research areas, ranging from robotics and intelligent vehicle highway systems to expert training and virtual reality computer games. Usually, HCS models are derived empirically, rather than analytically, from real-time human input–output data. While these empirical models offer an effective means of transferring intelligent behaviors from humans to robots and other machines, there is a great need to develop adequate performance criteria for these models. It is our goal in this paper to develop several such criteria for the task of human driving. We first collect driving data from different individuals through a real-time graphic driving simulator that we have developed, and identify each individual’s control strategy model through the flexible cascade neural network learning architecture. We then define performance measures for evaluating two aspects of the resultant HCS models. The first is based on event analysis, while the second is based on inherent analysis. Using the proposed performance criteria, we demonstrate the procedure for evaluating the relative skill of different HCS models. Finally, we propose an iterative algorithm for optimizing an initially stable HCS model with respect to independent, user-specified performance criteria, by applying the simultaneously perturbed stochastic approximation (SPSA) algorithm. The methods proposed herein offer a means for modeling and transferring HCS in response to real-time inputs, and improving the intelligent behaviors of artificial machines.

Proposed performance criteria for extended wear contact lenses

The introduction of silicone-hydrogel materials has changed expectations for the response to contact lenses used in extended wear. In keeping with this technology shift, we have re-evaluated the criteria by which practitioners judge the performance of extended wear lenses. Attendees at the 1999 Annual Clinical Conference of the British Contact Lens Association were surveyed. The proportion of respondents who considered it appropriate to fit selected patients with conventional, disposable and silicone-hydrogel soft lenses for extended wear was 63%, 67% and 86%, respectively. Only 11% of respondents did not fit extended wear because of personal experience with infectious keratitis, and over 50% relied on educators' advice in avoiding this practice. Fifteen per cent of practitioners reported fitting extended wear on occasions. Ninety-five per cent of respondents thought that the relative risk of infectious keratitis with daily wear compared with no lens wear should be ten or less, which was reduced to 60% when it was revealed that the current relative risk is estimated to be 60. A strong preference for a relative risk of infection with extended wear compared to daily wear of less than five times was indicated, which is consistent with current estimates. A minority of respondents were prepared to accept an overnight oedema level of over 6% with extended wear, although silicone-hydrogel materials have been shown to induce less than 4%. A wide variety of microcyst responses were considered reasonable, with many respondents accepting up to 40 per cornea; again, this result contrasted with early research data suggesting a level of 10 microcysts or less occurring with silicone-hydrogel materials. Interpretation of these findings has led us to the following proposals for safe extended wear: (i) extended wear fitting should preferably be done with silicone-hydrogel materials, rather than conventional hydrogels, where the available parameter ranges overlap; (ii) the relative risk of corneal infection with extended wear compared to daily wear should be two to five times, providing the relative risk of daily wear compared to the no lens wear'situation is reduced to 20 times, and (iii) extended wear lenses should produce an average of no more than 4% overnight oedema and no more than 10 microcysts per eye in the long term.

Performance analysis of wavelets in embedded zerotree-based lossless image coding schemes

In this correspondence, we present a modification to the scanning approach in the set partitioning algorithm proposed by Said and Pearlman (1996) to exploit the correlation in a local neighborhood. The wavelet filters are characterized based on the wavelet coefficients obtained after the wavelet transform. Two new criteria are proposed for evaluating the performance of wavelets in lossless image compression applications: cumulative zerotree count and monotone spectral ordering of subbands produced after wavelet transform in a multiresolution scheme. Several wavelet filters are evaluated to test the evaluation criteria. The experimental results are presented to justify the proposed performance criteria.

Proposed performance criteria for samplers of total suspended particulate matter

In order to facilitate intercomparison of dust concentrations measured with different samplers of total suspended particulates (TSP) the following scheme is proposed: based on regressions of experimental data permitting particle size values d 80 and d 50 ( d k is the particle diameter of the aerosol mass size distribution for which k per cent of the mass comes with particles smaller than d k ) as a function of wind speed, the knowledge of the average wind speed occurring during a typical sampling interval permits an assessment of the characteristic stop distances S 50, S 80 of the aerosol to be sampled. If the samplers are characterized by the maximum particle stop distance up to which they allow representative sampling, suitable correction factors derived from S 50, S 80 allow conservative estimates of the TSP concentration.

Proposed performance criteria for samplers of total suspended particulate matter

Abstract In order to facilitate intercomparison of dust concentrations measured with different samplers of total suspended particulates (TSP) the following scheme is proposed: based on regressions of experimental data permitting particle size values d 80 and d 50 ( d k is the particle diameter of the aerosol mass size distribution for which k per cent of the mass comes with particles smaller than d k ) as a function of wind speed, the knowledge of the average wind speed occurring during a typical sampling interval permits an assessment of the characteristic stop distances S 50 , S 80 of the aerosol to be sampled. If the samplers are characterized by the maximum particle stop distance up to which they allow representative sampling, suitable correction factors derived from S 50 , S 80 allow conservative estimates of the TSP concentration.

Performance Criteria for Constrained Nonlinear Programming Codes

A set of performance criteria for evaluating optimization software with respect to efficiency, reliability, and accuracy is presented and discussed. A numerical comparison of five constrained nonlinear programming codes is described, which was carried out in order to test the usefulness and general applicability of the proposed performance criteria. The results of the numerical comparison are discussed, and the proposed criteria are compared to the criteria traditionally used in comparative evaluations of nonlinear programming codes, with particular reference to machine dependence and the applicability to test problems with unknown solutions. A separate small scale computational experiment is described which was carried out specifically to test the machine dependence of the criteria. The observed deficiencies of the proposed new criteria are also discussed.

Self-learning--What is it?

The problems of self-learning are discussed, and a general method of solving these problems is described. Performance criteria for evaluating the quality of self-learning are given, and the algorithms for self-learning which minimize the proposed performance criteria are found. The ideas of optimal algorithms are introduced. In the conclusion, the special nature of the problems of self-learning is discussed.