Performance optimization of an air-standard irreversible dual-atkinson cycle engine based on the ecological coefficient of performance criterion.
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ABSTRACT:
SUBMITTER: Gonca G
PROVIDER: S-EPMC4138611 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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Project description:In current research, the hydraulic performance prediction and optimization of an engine cooling water pump was conducted by computational fluid dynamic (CFD) analysis. Through CFD simulation, the pump head, shaft power and efficiency for the original pump at volume flow rate 25 L/min and impeller rotating speed 4231 r/min were 3.87 m, 66.7 W and 23.09% respectively. For improving hydraulic performance, an optimization study was carried out. After optimization, four potential optimized designs were put forward. The efficiency of the optimized design No.1 for engine cooling water pump was nearly 6% higher than that of the original pump model; and the head of the optimized design No.2 for engine cooling water pump was 9% higher than that of the original pump model. Under the condition of maintaining the pump head and considering comprehensive improvement effect, the optimized design No.3 was considered as the best design and selected as the test case for validating the optimum design. The hydraulic performance predictions for this optimum engine cooling water pump agreed well with experimental data at design condition with relative discrepancies of 2.9% and 5.5% for the pump head and pump efficiency, respectively. It proved that performance prediction calculation model and the automatic optimization model were effective. This research work can provide theoretical basis for the design, development and optimization of engine cooling water pump.
| S-EPMC8205170 | biostudies-literature
Project description:Advanced sensor technology provides accurate information for transparent monitoring and real-time control of the power grid. Tunnel magnetoresistance (TMR) elements with high sensitivity and linearity provide a new technical means for current measurement in medium-voltage DC power distribution systems. This paper proposes a dual air-gap closed-loop TMR current sensor and its optimal design method based on the magnetic field's minimum uniformity coefficient. The dual air-gap structure reduces the measurement error caused by the eccentricity of the wire, and the theory and modelling of the minimum magnetic field uniformity coefficient optimise the key parameters, such as the inner radius of the magnetic core, the distance of the air-gap and the area size of the section side. Finally, a sensor prototype with a rated measurement current of ± 50 A was developed. The experiment results show that the relative error of the proposed TMR current sensor is less than 0.2% under the rated current. The conclusion can be drawn that the proposed sensor with the optimised design effectively improves the measurement accuracy.
| S-EPMC9816158 | biostudies-literature
Project description:MotivationVarious computational biology calculations require a probabilistic optimization protocol to determine the parameters that capture the system at a desired state in the configurational space. Many existing methods excel at certain scenarios, but fail in others due, in part, to an inefficient exploration of the parameter space and easy trapping into local minima. Here, we developed a general-purpose optimization engine in R that can be plugged to any, simple or complex, modelling initiative through a few lucid interfacing functions, to perform a seamless optimization with rigorous parameter sampling.ResultsROptimus features simulated annealing and replica exchange implementations equipped with adaptive thermoregulation to drive Monte Carlo optimization process in a flexible manner, through constrained acceptance frequency but unconstrained adaptive pseudo temperature regimens. We exemplify the applicability of our R optimizer to a diverse set of problems spanning data analyses and computational biology tasks.Availability and implementationROptimus is written and implemented in R, and is freely available from CRAN (http://cran.r-project.org/web/packages/ROptimus/index.html) and GitHub (http://github.com/SahakyanLab/ROptimus).
| S-EPMC10174700 | biostudies-literature
Project description:This research focuses on developing an improved and robust measurement for emergency department (ED) performance and a criterion standard for global use via kinetic analysis. Based on kinetic approach, the input-throughput-output conceptual model of ED crowding is compared to the procedure of enzyme catalysis. All in average, the retented patients in EDs are defined as substrate (S), whereas the patients who depart the EDs as product (P). Therefore, the average ED departure velocity (V) can be presented as (P)divided by a given time (t) of the ED length of stay (LOS). The S-V and S²-P plots are depicted hourly for the kinetic analysis. The long-term stability of the kinetic parameters is ascertained by the method of coefficient of variation (CV). The participants collected for this study are from the EDs of Changhua Christian Medical Center and the five branched hospitals, all located in Taiwan. Based on the S-V plot analysis, the results clearly show 2 curves, an upper and a lower curve. The timeline of the lower curve includes approximately the total ED busy hours, and thus it can be used for the subsequent kinetic analysis. In order to explore the adequate kinetic parameters for ED performance, the try-and-error process was followed in this study. As a result, the S²-V plots adapted from the lower curves show the best linear regression of S² on V with a good coefficient of determination (R). The Pan-Wen constant (PW), which is the slope of the liner regression line, and the ED medical personnel unit turnover number (EDMPU TON) were deduced from the kinetic meanings of (Equation is included in full-text article.)plots. In this research, the 2 kinetic parameters, PW and EDMPU TON were applied for the ED performance evaluations. An innovative relationship between the ED retented patients and the ED departure velocity is verified as PW; whereas, a feasible kinetic parameter, the EDMPU TON explicates the teamwork efficiency of the ED providers. Moreover, the EDMPU TON may not only be a reliable universal criterion standard for the ED performance, but also a valuable reference for both ED providers and payers.
| S-EPMC4839888 | biostudies-other
Project description:In this paper, we report data and experiments related to the research article entitled "An adaptive truncation criterion, for linesearch-based truncated Newton methods in large scale nonconvex optimization" by Caliciotti et al. [1]. In particular, in Caliciotti et al. [1], large scale unconstrained optimization problems are considered by applying linesearch-based truncated Newton methods. In this framework, a key point is the reduction of the number of inner iterations needed, at each outer iteration, to approximately solving the Newton equation. A novel adaptive truncation criterion is introduced in Caliciotti et al. [1] to this aim. Here, we report the details concerning numerical experiences over a commonly used test set, namely CUTEst (Gould et al., 2015) [2]. Moreover, comparisons are reported in terms of performance profiles (Dolan and Moré, 2002) [3], adopting different parameters settings. Finally, our linesearch-based scheme is compared with a renowned trust region method, namely TRON (Lin and Moré, 1999) [4].
| S-EPMC5790812 | biostudies-literature
Project description:BackgroundAnxiety disorders are the most prevalent mental disorders globally, with a substantial impact on quality of life. The prevalence of anxiety disorders has increased substantially following the COVID-19 pandemic, and it is likely to be further affected by a global economic recession. Understanding anxiety themes and how they change over time and across countries is crucial for preventive and treatment strategies.ObjectiveThe aim of this study was to track the trends in anxiety themes between 2004 and 2020 in the 50 most populous countries with high volumes of internet search data. This study extends previous research by using a novel search-based methodology and including a longer time span and more countries at different income levels.MethodsWe used a crowdsourced questionnaire, alongside Bing search query data and Google Trends search volume data, to identify themes associated with anxiety disorders across 50 countries from 2004 to 2020. We analyzed themes and their mutual interactions and investigated the associations between countries' socioeconomic attributes and anxiety themes using time-series linear models. This study was approved by the Microsoft Research Institutional Review Board.ResultsQuery volume for anxiety themes was highly stable in countries from 2004 to 2019 (Spearman r=0.89) and moderately correlated with geography (r=0.49 in 2019). Anxiety themes were predominantly long-term and personal, with "having kids," "pregnancy," and "job" the most voluminous themes in most countries and years. In 2020, "COVID-19" became a dominant theme in 27 countries. Countries with a constant volume of anxiety themes over time had lower fragile state indexes (P=.007) and higher individualism (P=.003). An increase in the volume of the most searched anxiety themes was associated with a reduction in the volume of the remaining themes in 13 countries and an increase in 17 countries, and these 30 countries had a lower prevalence of mental disorders (P<.001) than the countries where no correlations were found.ConclusionsInternet search data could be a potential source for predicting the country-level prevalence of anxiety disorders, especially in understudied populations or when an in-person survey is not viable.
| S-EPMC10131769 | biostudies-literature
Project description:SIGNIFICANCE:Uncorrected refractive error is a prevalent problem throughout the world especially among the low-income population who have limited access to professional eye care and cannot afford eyeglasses. PURPOSE:The purpose of this study was to evaluate the accuracy and usability of a low-cost, portable, smartphone-based autorefractor (Netra, EyeNetra Inc., Somerville, MA) in adults. METHODS:A cross-sectional study was conducted to compare the portable refractor with subjective (manifest and cycloplegic) refraction for sequential adult participants with best-corrected visual acuity of 20/40 or greater. For each method of refraction, the spherical equivalent was calculated. Differences between methods were tested with linear mixed regression models. A validated usability questionnaire was administered regarding ease of use (100-point scale, higher scores better) for the portable autorefractor. RESULTS:Eighty-seven subjects (152 eyes) were studied (age range, 20 to 90 years; mean ± standard deviation, 51.9 ± 18.3 years). Mean spherical equivalent by the portable device was -2.76 D (range, -14.75 to 3.63 D) compared with -2.49 D (range, -15.25 to 4.25 D) by manifest refraction. The mean relative difference in spherical equivalent between methods was -0.27 D (P = .001, significantly different than 0 D). The mean absolute difference between methods was 0.69 D (P < .001, significantly different than 0.5-D absolute difference). Similar results were found when comparing spherical equivalent between Netra and cycloplegic refraction methods. Subjects reported average ease of use for the Netra of 75.4 ± 19.8. CONCLUSIONS:The portable autorefractor had small but clinically significant differences from subjective refraction. The device's scores on the usability scale indicate good overall patient acceptance. The device may be valuable for use where there is limited access to a trained refractionist.
| S-EPMC6475906 | biostudies-literature
Project description:With advances in artificial intelligence and semantic technology, search engines are integrating semantics to address complex search queries to improve the results. This requires identification of well-known concepts or entities and their relationship from web page contents. But the increase in complex unstructured data on web pages has made the task of concept identification overly complex. Existing research focuses on entity recognition from the perspective of linguistic structures such as complete sentences and paragraphs, whereas a huge part of the data on web pages exists as unstructured text fragments enclosed in HTML tags. Ontologies provide schemas to structure the data on the web. However, including them in the web pages requires additional resources and expertise from organizations or webmasters and thus becoming a major hindrance in their large-scale adoption. We propose an approach for autonomous identification of entities from short text present in web pages to populate semantic models based on a specific ontology model. The proposed approach has been applied to a public dataset containing academic web pages. We employ a long short-term memory (LSTM) deep learning network and the random forest machine learning algorithm to predict entities. The proposed methodology gives an overall accuracy of 0.94 on the test dataset, indicating a potential for automated prediction even in the case of a limited number of training samples for various entities, thus, significantly reducing the required manual workload in practical applications.
| S-EPMC9748814 | biostudies-literature
Project description:BackgroundIrreversible electroporation (IRE) is a non-thermal cell ablation approach that induces selective damage to cell membranes only. The purpose of the current study was to evaluate and optimize its use for in-vivo myocardial decellularization.MethodsForty-two Sprague-Dawley rats were used to compare myocardial damage of seven different IRE protocols with anterior myocardial infarction damage. An in-vivo open thoracotomy model was used, with two-needle electrodes in the anterior ventricular wall. IRE protocols included different combinations of pulse lengths (70 vs. 100 ?seconds), frequency (1, 2, 4 Hz), and number (10 vs. 20 pulses), as well as voltage intensity (50, 250 and 500 Volts). All animals underwent baseline echocardiographic evaluation. Degree of myocardial ablation was determined using repeated echocardiography measurements (days 7 and 28) as well as histologic and morphometric analysis at 28 days.ResultsAll animals survived 28 days of follow-up. Compared with 50V and 250V, electroporation with 500V was associated with significantly increased myocardial scar and reduction in ejection fraction (67.4%±4% at baseline vs. 34.6%±20% at 28 days; p <0.01). Also, compared with pulse duration of 70 ?sec, pulses of 100 ?sec were associated with markedly reduced left ventricular function and markedly increased relative scar area ratio (28%±9% vs. 16%±3%, p = 0.02). Decreasing electroporation pulse frequency (1Hz vs. 2Hz, 2Hz vs. 4Hz) was associated with a significant increase in myocardial damage. Electroporation protocols with a greater number of pulses (20 vs. 10) correlated with more profound tissue damage (p<0.05). When compared with myocardial infarction damage, electroporation demonstrated a considerable likeness regarding the extent of the inflammatory process, but with relatively higher levels of extra-cellular preservation.ConclusionsIRE has a graded effect on the myocardium. The extent of ablation can be controlled by changing pulse length, frequency and number, as well as by changing electric field intensity.
| S-EPMC5125564 | biostudies-literature