In this paper, a strict linear Lyapunov function is developed in order to investigate the exponential stability of a linear hyperbolic partial differential equation with positive boundary conditions. ...Based on the method of characteristics, some properties of the positive solutions are derived for the hyperbolic initial boundary value problems. The dissipative boundary condition in terms of linear inequalities is proven to be not only sufficient but also necessary under an extra assumption on the velocities of the hyperbolic systems. An application to control of the freeway traffic modeled by the Aw-Rascle traffic flow equation illustrates and motivates the theoretical results. The boundary control strategies are designed by integrating the on-ramp metering with the mainline speed limit. Finally, the proposed feedback laws are tested under simulation, first in the free-flow case and then in the congestion mode, which show adequate performance to stabilize the local freeway traffic.
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•Properties of FHP and SHP was comparatively investigated.•A comprehensive exploration on rheological properties has been performed.•FHP exhibited more elastic characteristics, while ...its DE and Mw were both lower.
To investigate the characteristics of the pectins from fermented and steeped hawthorn wine pomace (FHP and SHP), they were acid-extracted, respectively, and compared detailedly. The results of esterification degree indicated that these two pectins were both defined as high methoxyl pectin, which was confirmed by Fourier transform infrared spectroscopy analysis. Molecular weight of SHP was higher than that of FHP. Differential scanning calorimetry analysis showed that the melt temperature of SHP was lower than that of FHP, and the molecular arrangement of SHP is more orderly than FHP. FHP and SHP solutions exhibited shear-thinning properties but SHP had a stronger anti-shear ability. FHP tended to be more elastic-solid as the concentration increased, which was not prominent in SHP. This study suggested that FHP and SHP powder could be new sources of pectin and both pectins could be potentially used as a thicker and stabilizer in food processing.
•UASB performances and microbial mechanisms under pH stress were investigated.•Methane yield was reduced by 25.3% under acidic pH of 5.0.•Primary bacterial communities caused propionate accumulation ...was found.•Desulfovibrio was dominant syntrophic acetogens.•Methanosaeta was dominant acetotrophic methanogens.
The operation performance and microbial mechanisms by pH stress were investigated during anaerobic digestion of sugar refinery wastewater in a upflow anaerobic sludge blanket (UASB) reactor to clarify correlations between pH stress, microbial community and process efficiency. Results showed that the COD removal and methane yield were respectively reduced by 24.8% and 25.3% as pH decreased to 5.0. pH decrease resulted in the composition of dominant fermentative acidogenic bacteria was changed to Butyricicoccus, Lactococcus, Brooklawnia, Armatimonadetes_gp2 and Megasphaera from Prevotella, Streptococcus, Acidaminococcus and Megasphaera, causing an increase in propionate production. In addition, the growth of propionate-oxidizing bacteria was also inhibited at pH 5.0, leading the propionate was accumulated, and then reduced the process efficiency. Methane was mainly produced through acetate cleavage by Methanosaeta during the whole operational period of UASB. pH decrease blocked the metabolic balance and community structure between different trophic groups, resulting in the decrease in reactor performance.
While nuclear compartmentalization is an essential feature of three-dimensional genome organization, no genomic method exists for measuring chromosome distances to defined nuclear structures. In this ...study, we describe TSA-Seq, a new mapping method capable of providing a "cytological ruler" for estimating mean chromosomal distances from nuclear speckles genome-wide and for predicting several Mbp chromosome trajectories between nuclear compartments without sophisticated computational modeling. Ensemble-averaged results in K562 cells reveal a clear nuclear lamina to speckle axis correlated with a striking spatial gradient in genome activity. This gradient represents a convolution of multiple spatially separated nuclear domains including two types of transcription "hot zones." Transcription hot zones protruding furthest into the nuclear interior and positioning deterministically very close to nuclear speckles have higher numbers of total genes, the most highly expressed genes, housekeeping genes, genes with low transcriptional pausing, and super-enhancers. Our results demonstrate the capability of TSA-Seq for genome-wide mapping of nuclear structure and suggest a new model for spatial organization of transcription and gene expression.
This paper investigates the complex causal relationships between various types of environmental regulatory instruments (ERI) and agri-firms' technological innovation employing fuzzy set qualitative ...comparative analysis (fsQCA). The study finds a well-designed set of ERI can promote technological innovation in agribusiness; control-command ERI cannot promote technological innovation in agribusiness solely, market-incentivized ERI is indispensable in promoting firms' innovation performance, implicit ERI plays an important role in promoting firms' innovation and voluntary ERI does not play a significant role in promoting firms' technological innovation. The government should coordinate among various types of ERI and improve the design of ERI to achieve a win-win situation for both economic and environmental performance in the agriculture sector.
Previous work has demonstrated that pre-treatment of waste activated sludge (WAS) with free nitrous acid (FNA i.e. HNO2) enhances the biodegradability of WAS, identified by a 20–50% increase in ...specific methane production in biochemical methane potential (BMP) tests. This suggests that FNA pre-treatment would enhance the destruction of volatile solids (VS) in an anaerobic sludge digester, and reduce overall sludge disposal costs, provided that the dewaterability of the digested sludge is not negatively affected. This study experimentally evaluates the impact of FNA pre-treatment on the VS destruction in anaerobic sludge digestion and on the dewaterability of digested sludge, using continuously operated bench-scale anaerobic digesters. Pre-treatment of full-scale WAS for 24 h at an FNA concentration of 1.8 mg NN/L enhanced VS destruction by 17 ± 1% (from 29.2 ± 0.9% to 34.2 ± 1.1%) and increased dewaterability (centrifuge test) from 12.4 ± 0.4% to 14.1 ± 0.4%. Supporting the VS destruction data, methane production increased by 16 ± 1%. Biochemical methane potential tests indicated that the final digestate stability was also improved with a lower potential from FNA treated digestate. Further, a 2.1 ± 0.2 log improvement in pathogen reduction was also achieved. With inorganic solids representing 15–22% of the full-scale WAS used, FNA pre-treatment resulted in a 16–17% reduction in the volume of dewatered sludge for final disposal. This results in significantly reduced costs as assessed by economic analysis.
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•FNA pre-treatment of WAS assessed by continuously operated bench-scale anaerobic digesters.•FNA pre-treatment enhanced VS destruction and the dewaterability of digested sludge.•FNA pre-treatment reduced the microbial risks of biosolids by enhancing pathogen removal.•FNA pre-treatment significantly reduced sludge disposal costs.
One of the important issues in the study of hybrid stochastic differential delay equations (SDDEs) is the automatic control, with consequent emphasis being placed on the asymptotic analysis of ...stability and boundedness. In the study of asymptotic properties, the robust stability has received a great deal of attention. The theory of robust stability shows how much perturbation a given stable hybrid SDDE can tolerate so that its perturbed system remains stable. Almost all results so far on the robust stability require that the underlying SDDEs be either linear or nonlinear with linear growth condition. However, little is known on the robust stability of nonlinear hybrid SDDEs without the linear growth condition, which is one of the key topics in this paper. The other key topic is the robust boundedness. The aim here is to answer the question: how much perturbation can a given asymptotically bounded hybrid SDDE tolerate so that its perturbed system remains asymptotically bounded?
This paper focuses on 6D pose estimation for weakly textured targets from RGB-D images. A 6D pose estimation algorithm (DOPE++) based on a deep neural network for weakly textured objects is proposed ...to solve the poor real-time pose estimation and low recognition efficiency in the robot grasping process of parts with weak texture. More specifically, we first introduce the depthwise separable convolution operation to lighten the original deep object pose estimation (DOPE) network structure to improve the network operation speed. Second, an attention mechanism is introduced to improve network accuracy. In response to the low recognition efficiency of the original DOPE network for parts with occlusion relationships and the false recognition problem in recognizing parts with scales that are too large or too small, a random mask local processing method and a multiscale fusion pose estimation module are proposed. The results show that our proposed DOPE++ network improves the real-time performance of 6D pose estimation and enhances the recognition of parts at different scales without loss of accuracy. To address the problem of a single background representation of the part pose estimation dataset, a virtual dataset is constructed for data expansion to form a hybrid dataset.
Coastal land reclamation (CLR), particularly port reclamation, is a common approach to alleviating land shortages. However, the spatial extent, percentages, and processes of these newly reclaimed ...ports are largely unknown. The Bohai Sea is the most concentrated area of port reclamation worldwide. Thus, this study addresses the changes in the different coastline types and port reclamation process in the area. The reclamation area of the 13 ports in the Bohai Sea in 2002-2018 was 2,300 km2, which decreased the area of the sea by 3%. The natural coastline length in Tianjin decreased by 47.5 km, whereas the artificial coastline length increased by 46.6 km. Based on the port boundary, however, only 26.3% of the reclaimed areas have been used for port construction, which concentrates in the Tianjin and Tangshan ports. The ratio of built-up area within the ports is only 32.5%, and approximately 48.3% of the reclaimed areas have no construction projects. The port land reclamation in the Bohai Sea has been undergoing periods of acceleration, peak, deceleration, and stagnation since 2002. Hence, future port reclamation should not be totally prohibited, and fine management should be conducted based on the optimization of the reclaimed port area. The innovation of this research is its analysis of the port internal land use pattern, the percentage of built-up area in the ports, and the sustainability of port reclamation policies. The findings have vital implications for scientifically regulating the spatial pattern and exploring the utility of port reclamation.
•High–T hydrothermal fluids have significant effect on Neoproterozoic seawater compositions.•The great majority of Nd in Neoproterozoic seawater originated from terrigenous materials.•The ...Neoproterozoic ocean was not well–mixed with respect to its Nd isotopic composition.•The Neoproterozoic deep sea is still widespread anoxic.
Rare earth element and Nd isotopic data for the recently discovered Neoproterozoic Dahongliutan banded iron formation (BIF) and associated carbonates are employed to infer aspects of the provenance and depositional environment, including ambient seawater compositions. The geochemical evidence is suggestive of deposition of the Dahongliutan marble in an epicontinental shallow–marine environment with riverine influx and low–T hydrothermal input, with restricted exchange to the open ocean. In contrast, the Dahongliutan BIF formed in a more open setting, with high–T hydrothermal input and old continental materials addition. The clearly distinct but negative εNd (0.593 Ga) values indicate that Neoproterozoic seawater at Dahongliutan could be spatially inhomogeneous with respect to 143Nd/144Nd ratios, owing to inefficient vertical and horizontal mixing of seawater closely related to the riverine Nd input derived from the weathering of different types and ages of continental crusts of the Western Kunlun orogenic belt and the Tarim Block. The Nd isotopic mass balance calculations of the Dahongliutan BIF indicate that most (>68%) of the Nd were derived from continental source materials transported by river water. In conjunction with previously published geochemical data of Neoproterozoic BIFs worldwide, we evaluate the chemical compositions of seawater where they formed, represented by a seawater reservoir strongly influenced by continentally derived freshwaters (>10%) mixed with open ocean and minor (<5%) high–T hydrothermal fluids as indicated by Sm/Yb and Eu/Sm ratios. By comparing the Nd isotopic features of Neoproterozoic BIFs, it is concluded that similar to modern oceans, the Neoproterozoic ocean was not well–mixed with respect to its Nd isotopic composition and continental source materials transported by river water dominated the great majority of Nd in Neoproterozoic seawater.
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