Chilling is a major constraint on rice production in mountainous regions of the tropics and in the temperate rice‐growing zones of the world. In this study, our goal is to quantify the impacts of ...chilling at the tillering phases on rice growth and grain yield. In 2017 and 2018, we conducted a factorial chilling treatment at four temperatures (T1, T2, T3 and T4) and four duration days (D2, D4, D6 and D8) on rice plants at the early, middle and late tillering phases. The results showed that chilling at the tillering phases delayed rice growth period. The rice grain yield slightly increased with decrease in chilling temperature but significantly decreased with increase in chilling duration at the tillering phases. For the chilling treatment at T1 (lowest temperature), the D2 (shortest duration) had positive effects on rice yield, while the D8 (longest duration) had adverse effects on rice yield. The middle and late tillering phases were the critical growth phases for rice spike numbers formation, with the increase in temperature and duration, the rice spike numbers per plant significantly decreased. The decrease in chilling temperature and increase in chilling duration both decreased rice thousand‐grain weight under chilling treatments at tillering phases. The prolongation of days from emergence to flowering led to increase in rice aboveground biomass per plant and allocation index of stem; however, the decrease in days from flowering to maturity led to reduction in allocation index of panicle and grain yield under chilling treatments at tillering phases. This study could help farmers to better understand the impacts of chilling on rice growth and yield, especially for rice that are prone to chilling.
•The seismic behavior of concrete slender columns was investigated.•The main parameters include stirrup space, concrete strength and axial load ratio.•The yield, maximum and failure points obtained ...from ABAQUS analysis were shown.•Parameter analysis on deformation and load at different service states was conducted.
To investigate the influence of longitudinal reinforcement strength grade, stirrup spacing, concrete strength and axial load ratio (ALR) on seismic behavior of high-strength concrete (HSC) columns, seven full-scale square HSC columns reinforced with high-strength steel bars (HSSB) with nominal yield strength of 600 MPa or conventional steel bars were tested under constant axial load and cyclic lateral load. Furthermore, corresponding nonlinear finite element analysis was conducted in ABAQUS. The column top deformation and lateral load at different service states, stiffness degradation, bearing capacity degradation and strain of longitudinal and transverse reinforcement were discussed. The test result shows that using steel bars with nominal yield strength of 400 MPa as stirrup is a better choice for HSC columns and ALR is an important factor which determines whether the high-strength longitudinal reinforcement can reach its compressive or tensile yield strain before maximum point. Taking HSSB as longitudinal reinforcement (equivalent volume replacement) greatly improves the seismic behavior of HSC columns. After taking the influence of strain gradient on stress-strain relationship of compressive concrete into consideration, a confined strain gradient model (CSGM) which was suitable for finite element analysis (FEA) was established based on the model established by Razvi and Saatcioglu. Specific verification of finite element model (FEM) on deformation and lateral load at different service states were presented for further parameter analysis. The trend of displacement ductility factor were investigated in detail in numerical analysis part. With proper ALR and stirrup characteristic value, HSC columns reinforced with HSSB is able to present a displacement ductility of higher than 4, which is capable to meet the ductility demand of most codes.
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•Energy yield of HTC for sewage sludge was calculated at different conditions.•Reaction severity played a significant role in HTC product characteristics.•Higher HHV of hydrochar was ...obtained at higher reaction severity.•Biomethane yield of process water was evaluated for all reaction severities.•Higher biomethane yield was achieved for process water at lower reaction severity.
Sewage sludge management is a major operational task that challenges sustainability in municipal wastewater treatment plants. On the other hand, the high level of organic carbon in sewage sludge suggests its utilization potential for renewable energy applications. This study investigates hydrothermal carbonization (HTC) of anaerobic sludge at increasing temperatures (200, 250 and 300 °C) and retention times (30, 60 and 120 min), providing a wide spectrum of reaction severities (logR0 = 4.4–8.0). The goal of the study was to quantify the energy recovery from hydrothermal co-products (i.e., hydrochar and process water) for their use as a solid fuel and a feedstock for anaerobic digestion (AD), respectively. The hydrochar yield was quantified and its quality was evaluated for elemental composition, higher heating value and combustion behavior using thermogravimetric analysis. The hydrothermal process water was analyzed for its chemical oxygen demand and biochemical methane potential. The hydrochar yield was negatively affected by reaction severity with the highest value of 73% at logR0 of 4.4 and the lowest value of 49% at logR0 of 8.0. On the other hand, the hydrochar quality was found to be positively influenced by reaction severity, which enhanced the reduction of oxygen by decarboxylation processes. The biomethane yields were also affected by the reaction severity, with the highest potential value of 227 mL CH4 g COD−1 at the lowest severity and the lowest potential value of 28 mL CH4 g COD−1 at the highest severity. An overall energy balance suggests that mild reaction severities can serve as a suitable platform returning more than 70% of the energy from anaerobic sludge using the HTC-AD process integration.
The flow behavior of soft materials below the yield stress can be rich and is not fully understood. Here, we report shear-stress-induced reorganization of three-dimensional solid-like soft materials ...formed by closely packed nematic domains of surfactant micelles and a repulsive Wigner glass formed by anisotropic clay nano-discs having ionic interactions. The creep response of both the systems below the yield stress results in angular velocity fluctuations of the shearing plate showing large temporal burst-like events that resemble seismic foreshocks-aftershocks data measuring the ground motion during earthquake avalanches. We find that the statistical properties of the quake events inside such a burst map on to the scaling relations for magnitude and frequency distribution of earthquakes, given by Gutenberg-Richter and Omori laws, and follow a power-law distribution of the inter-occurrence waiting time. In situ polarized optical microscopy reveals that during these events the system self-organizes to a much stronger solid-like state.
•Data-driven model based on CNN for predicting torsional strength of RC beams.•Proposed method outperforms existing methods by means of multiple evaluation metrics.•Sensitivity analysis was conducted ...to study the network inputs and output relationship.•A GUI was developed for the design of RC beams in practice.
This study presents the application of deep learning technology in torsional capacity evaluation of reinforced concrete (RC) beams. A data-driven model based on 2D convolutional neural network (CNN) is established, where model inputs contain the beam width, beam height, stirrup width, stirrup height, concrete compressive strength, steel ratio of longitudinal reinforcement, yield strength of longitudinal reinforcement, steel ratio of transverse reinforcement, yield strength of transverse reinforcement and stirrup spacing. To enhance the prediction accuracy of the proposed model, an improved bird swarm algorithm (IBSA) is leveraged to optimise the hyperparameters of CNN in the training phase. A comprehensive dataset, comprising 268 groups of laboratory tests of RC beams collected from published articles, is used for model development and validation. The results show that the proposed 2D CNN with hyperparameter optimisation exhibits high performance in predicting torsional strength of RC beams, which outperforms other machine learning models, building codes and empirical formula in terms of a series of evaluation metrics.
Bronchoscopy is commonly used to evaluate suspicious lung lesions. The yield is likely dependent on patient, radiographic, and bronchoscopic factors. Few studies have assessed these factors ...simultaneously while also including the preprocedure physician-assessed probability of cancer (pCA) when assessing yield.
This study is a secondary data analysis from a prospective multicenter trial. Diagnostic yield of standard bronchoscopy with biopsy ± fluoroscopy, endobronchial ultrasound with transbronchial needle aspiration (EBUS-TBNA), electromagnetic navigation, and combination bronchoscopies was assessed. Definitions for diagnostic and nondiagnostic bronchoscopies were rigorously predefined. The association of diagnostic yield with individual variables was examined by using univariate and multivariate logistic regression analyses where appropriate.
A total of 687 patients were included from 28 sites. Overall diagnostic yield was 69%; 80% for EBUS, 55% for bronchoscopy with biopsy ± fluoroscopy, 57% for electromagnetic navigation, and 74% for combination procedures (P < .001). Patients with larger, central lesions with adenopathy were significantly more likely to undergo a diagnostic bronchoscopy. Patients with pCA < 10% and 10% to 60% had lower yields (44% and 42%, respectively), whereas pCA > 60% yielded a positive result in 77% (P < .001). In multivariate logistic regression, the use of EBUS-TBNA, larger sized lesions, and central location were significantly associated with a diagnostic bronchoscopy. Seventeen percent of those with a malignant diagnosis and 28% of those with a benign diagnosis required secondary procedures to establish a diagnosis.
This study is the first to assess the yield of bronchoscopy according to physician-assessed pCA in a large, prospective multicenter trial. The yield of bronchoscopy varied greatly according to physician suspicion that cancer is present, the patients’ clinical/radiographic features, and the type of procedure performed. Of the procedures performed, EBUS-TBNA was the most likely to provide a diagnosis.
•Previous yield gap analyses have focused on individual crops.•We developed a framework to estimate cropping system yield potential and yield gap.•A proof-of-concept is provided with a case study on ...rice-maize cropping systems in Bangladesh.•The proposed framework identified opportunities to increase cropping system annual yield.
Yield gap analyses of individual crops have been used to estimate opportunities for increasing crop production at local to global scales, thus providing information crucial to food security. However, increases in crop production can also be achieved by improving cropping system yield through modification of spatial and temporal arrangement of individual crops. In this paper we define the cropping system yield potential as the output from the combination of crops that gives the highest energy yield per unit of land and time, and the cropping system yield gap as the difference between actual energy yield of an existing cropping system and the cropping system yield potential. Then, we provide a framework to identify alternative cropping systems which can be evaluated against the current ones. A proof-of-concept is provided with irrigated rice-maize systems at four locations in Bangladesh that represent a range of climatic conditions in that country. The proposed framework identified (i) realistic alternative cropping systems at each location, and (ii) two locations where expected improvements in crop production from changes in cropping intensity (number of crops per year) were 43% to 64% higher than from improving the management of individual crops within the current cropping systems. The proposed framework provides a tool to help assess food production capacity of new systems (e.g. with increased cropping intensity) arising from climate change, and assess resource requirements (water and N) and associated environmental footprint per unit of land and production of these new systems. By expanding yield gap analysis from individual crops to the cropping system level and applying it to new systems, this framework could also be helpful to bridge the gap between yield gap analysis and cropping/farming system design.
Wheat is the important food grain and is cultivated in many Indian states: Punjab, Haryana, Uttar Pradesh, and Madhya Pradesh, which contributes to major crop production in India. In this study, ...popular statistical approach multiple linear regression (MLR) and time series approaches Time Delay Neural Network (TDNN) and ARIMAX models were envisaged for wheat yield forecast using weather parameters for a case study area, i.e., Junagarh district, western Gujarat region situated at the foot of Mount Girnar. Weather data corresponds to 19 weeks (42nd to 8th Standard Meteorological Week, SMW) during crop growing season was used for prediction of wheat yield using these statistical techniques and were evaluated for their predictive capability. Furthermore, trend analysis among weather parameters and crop yield was also carried out in this study using non-parametric Mann–Kendall test and Sen’s slope method. Significant negative correlation was observed between wheat yield and some of the weekly weather variables, viz
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, maximum temperature (48, 49, 50, 51, 52, and 4th SMW), and total rainfall (50, 51, and 1st SMW) while positive correlation was observed with morning relative humidity (49 and 3rd SMW). Study indicated that forecast error varied from 1.80 to 10.28 in MLR, 0.79 to 7.79 in ARIMAX (2,2,2), − 3.09 to 10.18 in TDNN (4,5) during model training period (1985–2014). The MAPE value shows that the time series data predicted less than 5% of variation, whereas the conventional MLR technique indicated more than 7% variation. Both ARIMAX and TDNN approaches indicated better performance during model training periods, i.e., 1985–2014 and 1985–2015, while former performed well during the forecast periods 1985–2016 and 1985–2017. Overall, the study indicated that the ARIMAX approach can be used consistently for 4 years using the same model.
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•Suspensions of graphene oxide (GO) in Carbopol are also elastic yield stress fluids.•Addition of GO nanosheets in Carbopol decreases viscosity and elasticity.•Oxidation level of GO ...affects the rheological behavior.•Higher level of interaction of the GO/water system oxidized for 96 h.
This work investigates the rheology of graphene oxide (GO) suspension on a yield stress model fluid. The effects caused by the variation of the GO concentration in the suspension and by the amount of oxygenated groups pendant present on the nanosheets surface, on the rheology of the suspensions were evaluated. The dispersant used was an aqueous solution of Carbopol® Ultrez 10. This is a transparent, nontoxic elastic yield stress fluid. GO nanosheets were produced from synthesis of graphite oxide (GrO) by modified Hummers method, and the nanosheets were characterized by XRD, Raman, FTIR, TEM and AFM techniques. The rheological behavior of these suspensions was characterized by oscillatory and steady-state flow experiments. The GO structure characterization shows that oxygenated functional groups were incorporated in its graphite surface in different levels after using two distinct times of oxidation. GO oxidized for 96 h (GO 96 h) showed greater interplanar distance and also presented few layers when compared with GO oxidized for 2 h (GO 2 h). The GO exfoliation process directly into the aqueous dispersion of Carbopol® showed to be an effective method. As for the pure Carbopol solutions, the GO suspensions were well modeled by the Hershel-Bulkley equation. The increase of GO concentration in the suspensions impairs the level of fluid structure and leads to a decrease in viscosity, yield stress, and elasticity. When compared, the GO 96 h promoted a lower decrease in viscosity, yield stress and elasticity than the GO 2 h suspension. For the suspension with a higher concentration of GO 96 h, it was observed the appearance of hysteresis at low shear rates. These results show that small changes in the GO nanosheets surface can significantly influence the rheological responses of a non-Newtonian fluid.
One mechanism for airway closure in the lung is the surface-tension-driven instability of the mucus layer which lines the airway wall. We study the instability of an axisymmetric layer of ...viscoplastic Bingham liquid coating the interior of a rigid tube, which is a simple model for an airway that takes into account the yield stress of mucus. An evolution equation for the thickness of the liquid layer is derived using long-wave theory, from which we also derive a simpler thin-film evolution equation. In the thin-film case we show that two branches of marginally yielded static solutions of the evolution equation can be used to both predict the size of the initial perturbation required to trigger instability and quantify how increasing the capillary Bingham number (a parameter measuring yield stress relative to surface tension) reduces the final deformation of the layer. Using numerical solutions of the long-wave evolution equation, we quantify how the critical layer thickness required to form a liquid plug in the tube increases as the capillary Bingham number is increased. We discuss the significance of these findings for modelling airway closure in obstructive conditions such as cystic fibrosis, where the mucus layer is often thicker and has a higher yield stress.
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