This paper presents a torque ripple reduction approach to the direct torque control of a permanent magnet synchronous motor, using a sliding mode control technique. A distinctive feature of this ...approach is that, by appropriately parameterizing and implementing the sliding mode controller, the discontinuous nature of the voltage source inverter may be directly incorporated into the design process. The key idea is to incorporate the benefits of the variable structure systems control design and the event-driven sequential control structures in order to raise the system's performance and control efficiency. A predictive sliding-mode controller has been developed, designed as finite-state automata, and implemented using a field-programmable gate array (FPGA). This new FPGA logic regarding torque and speed control has been developed, analyzed, and experimentally verified.
Sustainability certification (SC) is one of the most popular private sector approaches to govern social and environmental outcomes of trade in products from agriculture, forestry and fisheries. Based ...on a sample of 175 peer-reviewed articles, we use a novel mixed methods meta-analytical approach to study the success of major sustainability certifications in promoting sustainable (primary) production practices. We consider both qualitative and quantitative studies. Our main data source are the discussion and conclusion sections of research papers. We analyze conclusive statements about the success of SCs and categorize them into favorable, mixed, and skeptical evaluations. The picture is dominated by skeptical conclusions. Subsequently, we analyze how specific study characteristics affect this evaluation. The distribution of favorable, mixed, and skeptical evaluations is largely similar across the areas of economic, social, and environmental sustainability. Over time, the share of skeptical evaluations has increased. Contextual factors such as primary sub-sector, or country show no significant effects. The evaluations are also largely consistent across different types of SCs. Studies focusing on endpoint sustainability outcomes evaluate the performance of SCs significantly more skeptical than studies that focus on intermediate sustainability outcomes. Furthermore, our study shows that the share of skeptical evaluations significantly increases when a study examines the success of SCs for outcome variables with high implementation costs. Overall, our review points towards a limited success of SCs.
•Identifying benchmarking peer for establishing an information security policy.•Feature engineering based on Vague Soft Set.•Improvements of Gaussian process classification by integrating Vague Soft ...Set.•Combined use of Gaussian process and Vague Soft Set performs best among classifiers.
Benchmarking methodology provides organizations with appropriate information security policy. However, selecting an appropriate organization as a benchmarking peer can be a challenge due to firms’ heterogeneous implementation and usage of information systems. Our goal is to develop and propose methods to appropriately identify a benchmarking peer organization by incorporating machine learning methods and mathematics set theory. We incorporate vague soft set, entropy, dynamic time warping, and Gaussian process. We use log data from information security management systems in multiple companies to validate our methods. Our experimental results indicate that the combined use of Gaussian process, vague soft set, and dynamic time warping can be more effective in identifying an appropriate benchmarking peer than conventional machine learning methods.
In several countries, during the grid faults, the large distributed generation (DG) is expected to support the voltage at the point of common coupling, as per the prevailing grid code. Large DGs are ...connected to a high voltage transmission line, where the voltage support is achieved by supplying the reactive power. The recent research trend, however, is toward voltage support by the medium size DGs that are connected to the resistive-inductive grid. The resistive-inductive grid requires both active and reactive power for voltage support. The existing voltage support schemes (VSS) for the resistive-inductive grid impose certain constraints on the proportion of active and reactive components of currents that adversely affect the performance. This article proposes a novel VSS that does not impose such constraints and provides enough compensation when available active power is not sufficient. It also provides the required compensation with much less active power curtailment when available active power is high. That is, the proposed scheme, in both cases, helps in achieving the same voltage compensation in spite of the nature of the injected current being significantly different. This feature is clearly demonstrated graphically using the vector diagram. The reference current expressions for the proposed VSS are analytically derived. The simulation and hardware results demonstrate that the proposed VSS achieves its objectives.
This study reports the test results of a two-stage stochastic linear programming (SLP) model with recourse using a user-friendly generic decision support system (DSS) in a North American steel ...company. This model has the flexibility to configure multiple material facilities, activities and storage areas in a multi-period and multi-scenario environment. The value of stochastic solution (VSS) with a real-world example has a potential benefit of US$ 24.61 million. Experiments were designed according to the potential joint probability distribution scenarios and the magnitude of demand variability. Overall, 144 SLP optimisation model instances were solved across four industries, namely, steel, aluminium, polymer and pharmaceuticals. The academic contribution of this research is two-fold: first, the potential contribution to profit in a steel company using an SLP model; and second, the optimisation empirical experiments confirm a pattern that the VSS and expected value of perfect information (EVPI) increase with the increase in demand variability. This study has implications for practicing managers seeking business solutions with prescriptive analytics using stochastic optimisation-based DSS. This study will attract more industry attention to business solutions, and the prescriptive analytics discipline will garner more scholarly and industry attention.
Ultrafast ultrasound imaging allows observing rapid phenomena; combined with 3-D imaging it has the potential to provide more accurate analysis on organs which leads, at the end, to better diagnosis. ...Coherent compounding using diverging waves is commonly used to reconstruct high quality images on large volumes while keeping frame rate high enough to allow dynamic analysis. In practice, the virtual sources that drive the diverging waves are often distributed by a deterministic way: following a regular grid, concentric rings and spirals. Even though those deterministic distributions can offer various trade-off in terms of imaging performance, other distributions can be considered to improve imaging performance. It is herein suggested to look at alternative virtual sources distributions for optimizing the lateral resolution and the secondary lobes level on several PSFs by means of a multiobjective genetic algorithm. The optimization framework leads to seven pseudo-irregular distributions of virtual source distributions that have not yet been found in the literature. An analysis on the imaging performance with a simulated phantom shows that these new distributions offer different trade-offs between lateral resolution and contrast, respectively measured on point-like reflectors and anechoic cysts. As an example, one of these optimized distributions improves the lateral resolution by 16% and gives equivalent contrast values on cysts, when compared to a concentric-rings-based distribution.
Scarring after burn injuries remains one of the major challenges in burn medicine and is the subject of current research. Accurate and high-quality assessment of scars is needed to enable exact ...outcome evaluation of different treatments. Our aim was to evaluate the most common subjective scar evaluation scores—the POSAS (Patient and Observer Scar Assessment Scale) and VSS (Vancouver Scar Scale)—in comparison with the objective device Mexameter® for colour evaluation.
A prospective monocentre study was performed, which included 120 examined scar areas of 60 patients with third degree burns who had received skin grafts between 1975 and 2018 with a total burned surface area (TBSA) > 2%. Two different scar areas in comparison with one healthy skin area concerning ‘colour’, ‘pigmentation’, and ‘vascularization’ were evaluated by the Mexameter® MX 18, the OSAS, and the VSS by the same examiner, as well as the PSAS by the patient.
The mean TBSA of the 60 patients was 24.3%. In the OSAS, 61% of the scars were evaluated as ‘hyper-’, 19% as ‘hypo-’, and 19% as ‘mix-pigmented’. Furthermore, 65% of the scars were estimated as highly vascularized. In the Mexameter®, the melanin index values of the scar areas compared to the healthy skin areas showed a small difference of 12 (p < 0.05). The mean difference of erythema between the scar and the healthy skin areas was 84 (p < 0.001). For the Mexameter®, moderate correlations were found when comparing ‘erythema’ with the OSAS category ‘vascularization’ (r = 0.33, p < 0.05) and ‘melanin’ with the OSAS parameter ‘pigmentation’ (r = 0.28, p < 0.05). When comparing the Mexameter® measurements to the OSAS questionnaire, 27% of the scars were wrongly evaluated as ‘hyperpigmented’ by the observer and 21% as ‘hypervascularized’, while showing low measurements in the device. Additionally, a novel Mexameter® ordinal scare scale was calculated.
In this study, we were able to show on a relatively large patient population that with the Mexameter®, the subjectivity of the scar colour assessment by examiner/patient can be overcome, but precise differentiation can still be ensured with subjective evaluation tools. We further introduced a novel Mexameter® Scar Scale. It is necessary to further investigate the vast range of objective devices and develop scar panels for with an incorporation of objective and subjective devices to further improve reliability with reduced bias in terms of scar assessment.
•Colour evaluation of scars and healthy skin with POSAS,VSS) compared to theMexameter®.•Precise differentiation of the colour properties of the scar can be ensured with the Mexameter®.•Presentation of a novel Mexameter® scar scale.
We demonstrate the performance of a dual frequency comb quantum cascade laser (QCL) spectrometer for the application of vibrational Stark spectroscopy. Measurements performed on fluorobenzene with ...the dual-comb spectrometer (DCS) were compared to results obtained using a conventional Fourier transform infrared (FT-IR) instrument in terms of spectral response, parameter estimation, and signal-to-noise ratio (S/N). The dual-comb spectrometer provided similar qualitative and quantitative data as the FT-IR setup in 250 times shorter acquisition time. For fluorobenzene, the DCS measurement resulted in a more precise estimation of the fluorobenzene Stark tuning rate ((0.81 ± 0.09) cm−1/(MV/cm)) than with the FT-IR system ((0.89 ± 0.15) cm−1/(MV/cm)). Both values are in accordance with the previously reported value of 0.84 cm−1/(MV/cm). We also point to an improvement of signal-to-noise ratio in the DCS configuration. Additional characteristics of the dual-comb spectrometer applicable to vibrational Stark spectroscopy and their scaling properties for future applications are discussed.
In forward blind source separation (FBSS) scenarios, subband adaptive filtering (SAF) algorithms provide fast convergence due to the SAF decorrelation ability. However, existing SAF algorithms suffer ...from a signal delay stemmed from the utilization of the synthesis filters. To solve this problem, we propose a delayless multisampled multiband-structured subband FBSS (DMSFBSS) algorithm by inserting a delayless multisampled multiband SAF structure. For a fixed SAF step-size, there is also a tradeoff between the convergence speed and steady-state error. We break this relationship by further developing an optimal DMSFBSS (ODMSFBSS) algorithm that minimizes the mean squared deviation (MSD) of DMSFBSS with respect to the subband gain vectors, to provide simultaneously fast convergence and low steady-state behavior. Intrinsically, the ODMSFBSS algorithm is an extension of the Kalman filtering theory over the subband-based FBSS structure. We also present an analysis of the algorithm stability. A vectorized implementation of the ODMSFBSS algorithm is proposed to reduce the computational complexity from <inline-formula> <tex-math notation="LaTeX">\mathcal {O}(L^{2}) </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">\mathcal {O}(L) </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">L </tex-math></inline-formula> is the length of the adaptive filter. Since adaptive FBSS scenarios require a voice activity detection (VAD) technique to control the alternating update of two adaptive filters, we develop two VAD approaches not relying on the priori knowledge of the speech source signal, thereby guaranteeing the practicability of the proposed ODMSFBSS algorithm. Simulation results in high and low SNR environments confirm that the proposed ODMSFBSS algorithm outperforms existing state-of-the-art algorithms.
