Periodicity and self-similarity of vortex evolution in a double-lid-driven cavity flow

AbstractThe flow configuration of the two-dimensional low Reynolds number flow in a rectangular cavity with two opposite moving lids and different depth-to-width ratios is investigated. The effects of aspect ratio varying from 0.15 to 6.6 on vortex structure in the cavity were numerated using the differential quadrature method. The critical aspect ratios, streamline patterns and bifurcation diagrams were presented. It is found that the vortex structure distributes in the transverse direction of cavity and the sub-eddy centers gradually merge as aspect ratio increases from 0.15 to 0.7. When the aspect ratio is larger than 0.7, the flow structure unfolds in the longitudinal direction of cavity and the number of vortices gradually increases with the aspect ratio increasing. The evolution of flow pattern exhibits the characteristics of periodicity and self-similarity. The large outer vortices evolve from the growth of new vortices in the middle region of cavity. The flow patterns are always symmetric about the cavity centre at different aspect ratios

Robust Predictive Speed Regulation of Converter-Driven DC Motors via a Discrete-Time Reduced-Order GPIO

Converter-driven direct current (dc) motors exhibit various advantages in industry, but impose several challenges to higher precision speed regulation in the presence of parametric uncertainties and exogenous, time-varying load torque disturbances. In this paper, the robust predictive speed regulation problem of a generic dc-dc buck converter-driven permanent magnet dc motors is addressed by using an output feedback discrete-time model predictive control algorithm. A new discrete-time reduced-order generalized proportional-integral observer (GPIO) is proposed to reconstruct the virtual system states as well as the lumped disturbances. The estimates of GPIO are then collected for output speed prediction. An optimized duty ratio law of the converter is obtained by solving a constrained receding horizon optimization problem, where the operational constraint on control input is explicitly taken into account. Finally, the effectiveness of the proposed new algorithm is demonstrated by various experimental testing results

Effect of fiber type and content on mechanical properties of microbial solidified sand

Fibers are applied to construction works to improve the strength and brittle failure of the soil. In this paper, fibers with a length of 6 mm are added to the microbial cemented sand, and fiber types and content are research variable. Unconfined compressive strength (UCS), permeability coefficient, water absorption rate, dry density, and calcium carbonate precipitation of the solidified sand were tested. The physical and mechanical properties of fiber types and content on the immobilization of microorganisms were also analyzed from the micro–macro perspective. Results are presented as follows. The UCS of the Microbial induced calcium carbonate precipitation (MICP) treated sand increases first and then decreases with the increasing fiber content. This phenomenon is due to the promotion of calcium carbonate precipitation by short fiber reinforcement, the limited movement of the sand particles caused by the formed network between the fibers, and the enhanced strength of the microbial solidified sand. However, the agglomeration caused by additional fibers leads to the uneven distribution of calcium carbonate and the reduction in strength. The optimum fiber contents of polypropylene, glass, polyvinyl alcohol, and basalt fibers are 0.4%, 0.2%, 0.2%, and 0.1%, respectively

Circulating Tumor DNA as a Sensitive Marker in Patients Undergoing Irreversible Electroporation for Pancreatic Cancer

Background/Aims: Pancreatic ductal adenocarcinoma (PDAC) is often diagnosed at an advanced stage, resulting in extremely poor 5-year survival. Late diagnosis of PDAC is mainly due to lack of a reliable method of early detection. Carbohydrate antigen (CA) 19-9 is often used as a tumor biomarker in PDAC; however, the test lacks sensitivity and specificity. Therefore, new sensitive and minimally invasive diagnostic tools are required to detect pancreatic cancer. Methods: Here, we investigated circulating tumor DNA (ctDNA) which contained KRAS-mutated as a potential diagnostic tool for PDAC patients who underwent irreversible electroporation (IRE). We used droplet digital polymerase chain reaction (ddPCR) to detect the expression of KRAS-mutated genes in plasma samples of 65 PDAC patients who underwent IRE. Results: In these 65 cases, ctDNA was detected in 20 (29.2%) samples. The median overall survival (OS) was 11.4 months with ctDNA+ patients and 14.3 months for ctDNA- patients. ctDNA+ patients had a obviously poorer prognosis associated to overall survival (P < 0.001). Conclusion: Our results suggested that the existence of ctDNA was a predictor of survival for PDAC patients. Therefore, ctDNA may be a new sensitive biomarker for monitoring treatment outcome in PDAC

Dietary Diversity and Nutrient Intake of Han and Dongxiang Smallholder Farmers in Poverty Areas of Northwest China

This study aimed to evaluate the status of dietary diversity and nutrient intake among Han and Dongxiang smallholder farmers in poor rural areas of northwest China. In this cross-sectional study, dietary intake was assessed in 499 smallholder farmers aged 18–75 years from two nationally designated impoverished counties in Gansu Province, China, using three consecutive 24 h dietary recalls. The dietary diversity score (DDS) and nutrient adequacy ratio (NAR) were adopted to assess dietary diversity and micronutrient adequacy, respectively. The mean DDS (range from 1 to 9) in participants was relatively low (3.81 ± 1.01). Consumption of grains was excessive, while consumption of vegetables, fruits, meat, beans, eggs, fish, and dairy was inadequate. The NAR values were higher in Han Chinese, with the exceptions of vitamin C, potassium, pyridoxine, and selenium (p \u3c 0.05). For each nutrient, the high DDS group had a higher mean NAR (p \u3c 0.05), except for pyridoxine. High household monthly income, being Han Chinese, high DDS, and being aged over 45 years were positively associated with mean adequacy ratio (MAR) of 14 micronutrients evaluated. Lack of dietary diversity and insufficient intake of essential micronutrients are public health concerns in northwest China. Nutrition education and other proper methods to address these issues are needed

Inferring causal molecular networks: empirical assessment through a community-based effort

It remains unclear whether causal, rather than merely correlational, relationships in molecular networks can be inferred in complex biological settings. Here we describe the HPN-DREAM network inference challenge, which focused on learning causal influences in signaling networks. We used phosphoprotein data from cancer cell lines as well as in silico data from a nonlinear dynamical model. Using the phosphoprotein data, we scored more than 2,000 networks submitted by challenge participants. The networks spanned 32 biological contexts and were scored in terms of causal validity with respect to unseen interventional data. A number of approaches were effective, and incorporating known biology was generally advantageous. Additional sub-challenges considered time-course prediction and visualization. Our results suggest that learning causal relationships may be feasible in complex settings such as disease states. Furthermore, our scoring approach provides a practical way to empirically assess inferred molecular networks in a causal sense

Prediction of overall survival for patients with metastatic castration-resistant prostate cancer : development of a prognostic model through a crowdsourced challenge with open clinical trial data

Background Improvements to prognostic models in metastatic castration-resistant prostate cancer have the potential to augment clinical trial design and guide treatment strategies. In partnership with Project Data Sphere, a not-for-profit initiative allowing data from cancer clinical trials to be shared broadly with researchers, we designed an open-data, crowdsourced, DREAM (Dialogue for Reverse Engineering Assessments and Methods) challenge to not only identify a better prognostic model for prediction of survival in patients with metastatic castration-resistant prostate cancer but also engage a community of international data scientists to study this disease. Methods Data from the comparator arms of four phase 3 clinical trials in first-line metastatic castration-resistant prostate cancer were obtained from Project Data Sphere, comprising 476 patients treated with docetaxel and prednisone from the ASCENT2 trial, 526 patients treated with docetaxel, prednisone, and placebo in the MAINSAIL trial, 598 patients treated with docetaxel, prednisone or prednisolone, and placebo in the VENICE trial, and 470 patients treated with docetaxel and placebo in the ENTHUSE 33 trial. Datasets consisting of more than 150 clinical variables were curated centrally, including demographics, laboratory values, medical history, lesion sites, and previous treatments. Data from ASCENT2, MAINSAIL, and VENICE were released publicly to be used as training data to predict the outcome of interest-namely, overall survival. Clinical data were also released for ENTHUSE 33, but data for outcome variables (overall survival and event status) were hidden from the challenge participants so that ENTHUSE 33 could be used for independent validation. Methods were evaluated using the integrated time-dependent area under the curve (iAUC). The reference model, based on eight clinical variables and a penalised Cox proportional-hazards model, was used to compare method performance. Further validation was done using data from a fifth trial-ENTHUSE M1-in which 266 patients with metastatic castration-resistant prostate cancer were treated with placebo alone. Findings 50 independent methods were developed to predict overall survival and were evaluated through the DREAM challenge. The top performer was based on an ensemble of penalised Cox regression models (ePCR), which uniquely identified predictive interaction effects with immune biomarkers and markers of hepatic and renal function. Overall, ePCR outperformed all other methods (iAUC 0.791; Bayes factor >5) and surpassed the reference model (iAUC 0.743; Bayes factor >20). Both the ePCR model and reference models stratified patients in the ENTHUSE 33 trial into high-risk and low-risk groups with significantly different overall survival (ePCR: hazard ratio 3.32, 95% CI 2.39-4.62, p Interpretation Novel prognostic factors were delineated, and the assessment of 50 methods developed by independent international teams establishes a benchmark for development of methods in the future. The results of this effort show that data-sharing, when combined with a crowdsourced challenge, is a robust and powerful framework to develop new prognostic models in advanced prostate cancer.Peer reviewe

Theoretical and experimental study on multiscale coupled Mohr–Coulomb shear strength criterion of fibre-reinforced sand

Fibre-reinforced sand (FRS) is a multiphase and multiscale geo-material, which is widely used in geotechnical engineering as supporting structure of excavation of underground space and reinforcement of foundation of underground structures, and its strength is determined by the properties of the heterogeneous substances of the FRS and their coupling mechanical responses. In order to investigate the influence of fibre characteristics and mechanical properties on the shear strength of the FRS, according to the microscopic interface slip effect generated by the interaction between sand particles and the interaction between these particles and fibre, the material phase of the FRS is divided to conceptualize a micro cell element of the FRS that is capable of reflecting the internal material characteristic information of the FRS. Moreover, based on the coordinated deformation condition between fibres and sand particles at the microscale and the couple stress theory that is capable of effectively describing the discontinuous mechanical responses at the sand-fibre interface, a mesomechanism-based multiscale Mohr–Coulomb shear strength criterion of the FRS is derived, and the yield locus of the FRS is also drawn on the π plane. Furthermore, a series of FRS samples with different fibre content and fibre length were prepared by adopting the freezing method, and consolidated and drained triaxial compression tests were conducted on these samples to validate the proposed multiscale coupled Mohr–Coulomb shear strength criterion. Results show that the multiscale coupled Mohr–Coulomb shear strength criterion is capable of effectively reproducing and predicting the yield strength of the FRS. The yield locus of the FRS extends outwards as fibre content and fibre length increase. The yield stress of the FRS predicted by the proposed multiscale coupled Mohr–Coulomb shear strength criterion is in good agreement with that of the test result

Comparing two models of gradient elution in counter-current chromatography.

International audienceGradient change of mobile phase composition is commonly used in liquid chromatography to shorten analysis duration. Gradient elution is possible in counter-current chromatography if it is demonstrated that the mobile phase composition changes are not associated with liquid stationary phase composition changes. Also, the solute distribution ratios in initial (1) and final (2) eluting systems must be known. If the solute distribution ratios during the changing mobile phase composition are modeled, the full gradient separation can be modeled using classical equations of liquid chromatography. Another approach allowed modeling empirically the gradient step. It considered the decreasing volume of mobile phase 1 and the increasing volume of mobile phase 2 used at each gradient time to derive a very simple equation. The two equations were compared computing the retention volumes of five test solutes. A remarkable agreement was observed considering the very different mathematical expressions of the two models. The step-gradient method was also modeled and its results compared to those of the linear gradient method