Search

The consolidation of soil is one of the most common phenomena in geotechnical engineering. Previous studies for the axisymmetric consolidation of unsaturated soil have usually idealized the boundary conditions as fully drained and absolutely undrained, but the boundaries of unsaturated soil are actually impeded drainage in most practical situations. In this study, we present a general analytical solution for predicting the axisymmetric consolidation behavior of unsaturated soil that incorporates impeded drainage boundary conditions in both the radial and vertical directions simultaneously. The impeded drainage boundary is modeled using the third kind boundary, and it can also realize fully drained and absolutely undrained ones by changing the drainage parameter. A general analytical solution is developed to predict the excess pore-air and pore-water pressures as well as the average degree of consolidation in an unsaturated soil stratum using the common methods of eigenfunction expansion and Laplace transform. The newly developed solution is expressed in the product of the terms of time, depth, and radius, which are derived using Laplace transform, usual Fourier, and Fourier-Bessel series, respectively. The eigenfunctions and eigenvalues are evaluated from the impeded drainage boundaries in both radial and depth dimensions. Then, the correctness of the proposed analytical solution is verified against the existing analytical solution for the case of traditional boundaries and against the finite difference solution for the case of general impeded drainage boundaries, and excellent agreements are obtained. Finally, the axisymmetric consolidation behavior of unsaturated soil involving impeded drainage boundaries is demonstrated and analyzed, and the effects of the drainage parameters are discussed. The results indicate that the larger drainage parameter generally expedites the dissipations of the excess pore pressures and further promotes the soil settling process. As the drainage parameter increases, its influence gradually diminishes and even can be neglected when it is larger than 100. The general analytical solution and findings of this study can help for better understanding the axisymmetric consolidation behavior of the unsaturated soil stratum in the ground improvement project with vertical drains as well as the gas-oil gravity drainage mechanism in the naturally fractured reservoirs. [ABSTRACT FROM AUTHOR]

Land subsidence resulting from the withdrawal of groundwater is one of the problems of major importance to geosciences and geomechanics. In order to analyze the phenomena of land subsidence, this study attempts to constitute a more reliable prediction model to simulate the consolidation process of the aquifer system under the drawdown of groundwater. A fractional-derivative viscoelastic model is introduced to characterize the rheological properties of the aquitard, and the equation governing the consolidation process is established on the basis of the one-dimensional consolidation theory. The semianalytical solutions for the pore-water pressure, the settlement of aquitard, and the degree of consolidation are deduced using both finite sine transform and Laplace transform. Then, the comparisons of two special cases are performed to validate the correctness of the proposed model. The variations in the degree of consolidation and settlement of the aquitard are simulated to analyze the consolidation behavior of the aquifer system, and the influences of model parameters and the drawdown speed of groundwater are investigated. [ABSTRACT FROM AUTHOR]

Queen reproductive potential (=quality) impacts the health and productivity of honey bee colonies. To determine the factors that affect reproductive quality during development, we tested queens produced under larval treatments by supplementing the diet with juvenile hormone (JH), additional sugars, or both, compared to untreated control. Furthermore, we varied the age of the larvae that were grafted (1 and 3 days old). We analyzed newly emerged virgin queens for their morphological characters as proxies for their reproductive potential. We found that the application of a sugar-enriched diet in combination with JH application onto 1st instar queen larvae produced higher-quality queens, while for 3rd instar larvae only the JH treatment resulted in increasing queen quality. For mated queens, those treated with JH plus supplemented sugars showed a significantly higher sperm count and sperm viability. Our findings demonstrate that honey bee queen reproductive potential can be increased through diet supplementation. [ABSTRACT FROM AUTHOR]

Summary This paper presents a general solution to the consolidation system of viscoelastic soil by vertical drains incorporating a fractional‐derivative model and arbitrary time‐dependent loading. The fractional‐derivative Merchant model is introduced to describe the viscoelastic behavior of saturated soil around the vertical drains. Based on this model, the governing partial differential equation of a consolidation system incorporating vertical and horizontal drainage is obtained for the equal strain condition. Then, a general solution to the consolidation system involving arbitrary time‐dependent loading is derived using the Laplace transform technique and eigenfunction expansion method. Further, two comparisons are presented to verify the exactness of the proposed solution, and the consolidation behavior involving four time‐dependent loadings is illustrated and discussed. [ABSTRACT FROM AUTHOR]

A two-dimensional axisymmetric CFD method is proposed for the solar chimney power plant (SCPP), which includes a solar radiation model within the collector, an energy storage model, an air flow and heat transfer model, and a turbine model. Numerical simulation is conducted for the Manzanares pilot plant. Different solar radiation modes in the collector and simulation methods are compared and discussed. Results show that the present two-dimensional method obtains consistent results with the three-dimensional method in the literature and experiment data, validating the feasibility of the proposed two-parallel-plate model for the radiation heat transfer within the collector. [ABSTRACT FROM AUTHOR]

Oxidative stress can lead to premature aging symptoms and cause acute mortality at higher doses in a range of organisms. Oxidative stress resistance and longevity are mechanistically and phenotypically linked; considerable variation in oxidative stress resistance exists among and within species and typically covaries with life expectancy. However, it is unclear whether stress-resistant, long-lived individuals avoid, repair, or tolerate molecular damage to survive longer than others. The honey bee ( Apis mellifera L.) is an emerging model system that is well-suited to address this question. Furthermore, this species is the most economically important pollinator, whose health may be compromised by pesticide exposure, including oxidative stressors. Here, we develop a protocol for inducing oxidative stress in honey bee males (drones) via Paraquat injection. After injection, individuals from different colony sources were kept in common social conditions to monitor their survival compared to saline-injected controls. Oxidative stress was measured in susceptible and resistant individuals. Paraquat drastically reduced survival but individuals varied in their resistance to treatment within and among colony sources. Longer-lived individuals exhibited higher levels of lipid peroxidation than individuals dying early. In contrast, the level of protein carbonylation was not significantly different between the two groups. This first study of oxidative stress in male honey bees suggests that survival of an acute oxidative stressor is due to tolerance, not prevention or repair, of oxidative damage to lipids. It also demonstrates colony differences in oxidative stress resistance that might be useful for breeding stress-resistant honey bees. [ABSTRACT FROM AUTHOR]

• SALSCS demonstration unit in Xi 'an, China is introduced. • A three-dimensional numerical simulation method considering the non-uniformity of solar irradiation is presented. • A sunshine fraction k T that reflects weather conditions is proposed. • The assumption of uniform incident solar radiation overestimates the system thermal airflow rate. Solar-Assisted Large-Scale Cleaning System (SALSCS) is a new attempt to alleviate outdoor air pollution by using solar energy. A demonstration unit was built in Xi 'an, China, in 2016. Field tests and numerical simulations were carried out on the demonstration unit in January 2017. Results show that the thermal airflow rate of the south collector is well predicted, while that of the north collector is seriously overestimated, with a deviation between the simulated value and the measured value being as larger as 47.07%. In this paper, an improved numerical simulation method considering the non-uniformity of solar irradiation, the effects of weather condition and the photovoltaic panels of the collector top is presented. Simulation results show that the deviation between the simulated thermal airflow rate of the north collector and the measured value is only 2.13%. Photovoltaic panels on the collector top have a little influence on the thermal airflow rate of the collectors. If the roof of the north and south collectors is covered with all photovoltaic panels, the thermal airflow rate will be reduced only by 6.93% and 7.99%, respectively. [ABSTRACT FROM AUTHOR]

In most practical consolidation problems, impeded drainage boundaries are a great concern. By simultaneously introducing the impeded drainage boundaries in the horizontal and vertical directions, this study attempts to constitute a general two-dimensional (2D) plane strain consolidation system of unsaturated soil. A newly analytical solution is developed to calculate the excess pore-air and pore-water pressures and average degree of consolidation. On the basis of the eigenfunction expansion method, the developed analytical solution is given as a product of three functions, including one variable of time, horizontal and vertical dimensions only. For the impeded drainage boundaries, the eigenfunctions and eigenvalues are derived in the horizontal and vertical dimensions. The Laplace transform technique is further adopted to solve the ordinary differential system in the time domain. The developed analytical solution is verified with the existing analytical/semi-analytical solutions and finite difference solution for several typical cases. Excellent agreements are obtained so that the correctness of the developed analytical solution is validated. Moreover, two worked examples are presented to show the superiority of the developed analytical solution and to assess the influences of the drainage parameters on the 2D plane strain consolidation behavior of unsaturated soil. [ABSTRACT FROM AUTHOR]

In preloading ground improvement projects, vertical drains are frequently installed to accelerate the consolidation process of a soil stratum which is generally unsaturated and layered in natural. To address such issue, this study attempts to constitute a reliable two-dimensional (2D) plane strain consolidation system of layered unsaturated soil. A novel semi-analytical solution for this system is developed using the methods of Fourier expansion, Laplace transform and their inversions. In order to obtain the final solution, the proposed system is firstly converted into a set of ordinary differential systems using the methods of Fourier expansion and Laplace transform. By defining a set of new variable vectors, these ordinary differential systems are further changed into diagonal ones and solved. Then, the semi-analytical solutions for the pore-air and pore-water pressures and the soil settlement are formulated, and numerical inversion of Laplace transform is applied to obtain the final results in temporal domain. Through comparing against the existing solution and the finite difference solution, the validity and the accuracy of the proposed solutions are verified. Moreover, a worked example incorporating a step load is presented to illustrate the 2D plane strain consolidation behavior of layered unsaturated soil and the influence from the coefficient of horizontal permeability is investigated. [ABSTRACT FROM AUTHOR]

This paper presents a novel analytical solution for one dimensional consolidation system of unsaturated soil incorporating impeded drainage boundary conditions. Through diagonalizing the coefficient matrix, the consolidation system is firstly transformed into a diagonal one with respect to a new variable vector. Then, using the methods of eigenfunction expansion and undetermined coefficients, the analytical solution is developed through deriving the eigenvalues, corresponding eigenfunctions and undetermined coefficients. Its orthogonality and convergence are proven, and several comparisons against existing solutions and two typical experimental data are performed to verify its validity. Finally, two typical examples are provided to illustrate the consolidation behavior of unsaturated soil with different drainage parameters. The results indicate that the present analytical solution converges rapidly, and it is consistent with existing analytical, semi-analytical and numerical solutions for various drainage boundary conditions. The proposed analytical solution achieves an overall better agreement with experimental data, and the impeded drainage boundary condition is more reasonable to describe the consolidation phenomenon of unsaturated soil. In general, larger drainage parameter accelerates excess pore-pressure dissipation and soil settlement. [ABSTRACT FROM AUTHOR]

• Small test setups for both pure and hybrid solar chimney system are built. • A numerical simulation method for the hybrid system is proposed and validated. • Hybrid systems greatly increase the total power output. • Hybrid systems can reduce land requirement of the solar-assisted air cleaning system. Under the background of global energy shortage and environment deterioration, researchers of the world pay high attention to develop renewable energy. This paper proposes a hybrid solar chimney and photovoltaic system for the novel solar-assisted air cleaning system. Small-scale laboratory setups are designed and fabricated. Experimental results reveal that replacing 50.60% acrylic glass of the collector top with photovoltaic panels will reduce the thermal air flow rate only by 14%, but generate significant electric power output. A three-dimensional numerical simulation model is established and validated by experimental results (air flow rate, temperature distribution). The model includes solar ray tracing model, surface to surface radiation model, buoyancy-driven flow and heat transfer model and power generation model. Then, this model is used to predict a large-scale system based on the Manzanares pilot power plant in Spain. For the large-scale system, the electrical energy generated by the photovoltaic panels can be used to drive suction fans to increase air input. Covering the entire top surface of the collector by photovoltaic panels (113-meter-wide), the total air flow rate would increase to 2.21 times compared with the system without photovoltaic panels. And setting photovoltaic panels on the collector bottom with 113-meter-wide, the total air flow rate would increase to 2.42 times. Thus, adding photovoltaic panels for the collector can greatly improve the utilization of solar energy. It can increase the amount of air purification, or reduce land requirement for the same flow rate. [ABSTRACT FROM AUTHOR]

Objective Modify hydroxyapatite whisker (HAPw) by nano zinc oxide(ZnO) to synthesize a kind of antibacterial implant bone compound material, and study its degradation and substantial changing in extreme environment. Methods Nano ZnO was prepared through sol-gel method, and modified HAPw by nano ZnO to achieve nano ZnO-HAPw compound material. According to ISO 10993-14 standards,the degradation rate of nano ZnO-HAPw was tested after soaked in citrate buffer solution, the surface morphology change was examined with by scanning electric microscope(SEM) and XRD analysis. Results The degradation rate was 25.44% (HAPw/n-ZnO),18.59% (HAPw), respectively. SEMshowed apparently that HAPw fractured and the quantities of nano ZnO particles significantly reduced after soaking. XRD analysis indicated that the three strong peaks of HAPw lowered. Conclusion Nano ZnO-HAPw is a low soluble materials. [ABSTRACT FROM AUTHOR]

Abstract: Elucidating the mechanisms by which honey bees process pollen vs. protein supplements are important in the generation of artificial diets needed to sustain managed honeybees. We measured the effects of diet on protein concentration, hypopharyngeal gland development and virus titers in worker honey bees fed either pollen, a protein supplement (MegaBee), or a protein-free diet of sugar syrup. Workers consumed more pollen than protein supplement, but protein amounts and size of hypopharyngeal gland acini did not differ between the two feeding treatments. Bees fed sugar syrup alone had lower protein concentrations and smaller hypopharyngeal glands compared with the other feeding treatments especially as the bees aged. Deformed wing virus was detected in workers at the start of a trial. The virus concentrations increased as bees aged and were highest in those fed sugar syrup and lowest in bees fed pollen. Overall results suggest a connection between diet, protein levels and immune response and indicate that colony losses might be reduced by alleviating protein stress through supplemental feeding. [Copyright &y& Elsevier]