Investigating the Physical Properties and Fragmentation of the AFGL 333-Ridge

We present multiwavelength data to investigate the physical properties and fragmentation of AFGL 333-Ridge. A statistical analysis of velocity dispersion indicates that turbulence is the dominant motion in the ridge. However, the linear mass density (1124.0 M ⊙/pc) of AFGL 333-Ridge far exceeds its critical value of 406.5 M ⊙/pc, suggesting that additional motions are required to prevent the filament radial collapse. Using the getsources algorithm, we identified 14 cores from the Herschel maps, including two protostellar cores and 12 starless cores. All of these starless cores are gravitationally bound, and are therefore considered to be prestellar cores. Based on their radius-mass relation, 11 of 14 cores have the potential to form massive stars. Moreover, the seven cores in two subfilaments of AFGL 333-Ridge seem to constitute two necklace-like chains with a spacing length of 0.51 and 0.45 pc, respectively. Compared the spacing length with theoretical prediction lengths by Jeans and cylindrical fragmentations, we argued that the combination of turbulence and thermal pressure may lead to the fragmentation of the two subfilaments into the cores.

A Model for Correcting the Pressure Drop between Two Monoliths

This paper is concerned with the modeling of the pressure drop through monolith honeycombs. Monolith substrates are promising for the intensification of catalytic processes, especially because of their low back-pressure. There have been several improvements in the modeling of monolith reactors during the last decade, most of them focused on a single substrate configuration, while research in multiple substrates in a single reactor is still sparse. One example is the so-called "minor losses", such as those because of the flow entering and leaving a substrate. Both phenomena interact when two monoliths are placed close in series, and the extra losses produced by them may become relevant when relatively short monoliths are used. In this paper, a spatially resolved computational model of monolith channels arranged in series is used to compute the extra pressure drop because of the flow leaving one substrate and entering the next one downstream. Several Reynolds numbers and spacing lengths for the channels between substrates are investigated. According to the results, for close-coupled monoliths, the inlet and outlet effects produce a negligible pressure drop compared to that in a single monolith configuration. This phenomenon can be accounted for by introducing a correction factor. The magnitude of the correction factor depends on the channel’s Reynolds number, diameter, and spacing length. A model for such a factor is proposed. The model accurately predicts the trend and magnitude of the correction factor.

Simulation and Analysis of Influencing Factors of Solar Energy Inter-seasonal Soil Heat Storage

Taking an office building in Jinan as an example, the simulation model of solar inter-seasonal soil heat storage was established by TRNSYS software, and the variation law of ground temperature in the heat storage period was analyzed. From the perspective of ground temperature change, the influence of the spacing, length, number of drilling wells and area of solar collector on the heat storage effect was analyzed. The results showed that the soil temperature increased rapidly at the beginning of heat storage, and then the temperature rise rate gradually slowed down. The ground heat exchanger spacing, length, number of drilling and collector area will have a great influence on the solar energy seasonal heat storage effect. Therefore, in practical engineering applications, for the solar inter-seasonal soil heat storage system, the parameters of buried pipes, collectors and other components are recommended to be reasonably determined by simulation to obtain the optimal heat storage effect.

Effect of Spacing between Stone Columns on the Behavior of Soft Soil

Soil improvement by stone columns is extensively used, especially for the soft ones. This is because of their efficiency and no environmental impact. Several factors affect its efficiency in improving the mechanical properties of the soil, and the most important of these factors are the spacing, length, and diameter of the stone columns. In this study, the finite element method was used to study the impact of the spacing between the stone columns on the amount of settlement and the bearing capacity of the soil. The study comprises three different spaces (s) that were taken in relation to the columns’ diameter (d), which are (s/d= 3, 4, and 5). In addition, three types of the sectional shape of column involved circular, rectangular, and square sections with different lengths of (L/d=2, 4, 6, 8, and 10). The results showed that the spacing between the stone columns is effective when the vertical load is greater than 30 kN/m2, and below this, there is no effect of the spacing. In general, the settlement decreases, and the bearing capacity increases with the decrease in the spacing between the stone columns. The spacing becomes a more pronounced effect with the longer length of the stone columns. All sections of the stone columns with a short length of (L/d=2) showed the same settlement of 271 mm at a distance (s/d=5), which decreases by 7.4, 6.6, and 8.9% at a distance (s/d=3) for the circular, rectangular and square sections respectively. In the case of long columns (L/d=10), the settlement at (s/d=3) improves by about 27.5% which drop to about 18% at (s/d=5). A slight improvement in the soil's bearing capacity is associated with decreases in the spacing between the stone columns. The improvements in the bearing of soil treated with short columns (L/d=2) are 6.0, 6.5, and 4.7% for circular, rectangular, and square sections, respectively, when changing the distance from (s/d=5) to (s/d=3). Whereas they become greater when increasing the columns’ length to (L/d=10) to be 7.9, 9.2, and 6.4%.

Effects of Various Processing Methods on the Ultrastructure of Tendon Collagen Fibrils from Qinchuan Beef Cattle Observed with Atomic Force Microscopy

Atomic force microscopy was utilized to study the effects of ultrasound oscillation, microwave heating, water bath cooking, and acid-base soaking on the ultrastructure of collagen fibrils of Qinchuan beef cattle tendons. D-spacing length and roughness of collagen fibrils always showed a 1.02% increment in the group which was processed for 20 min rather than for 10 min under different ultrasound frequencies. Microwave heating had a slight impact on D-spacing length and roughness at lower power (140–560 W), and collagen fibrils always showed a 1.02% increment for 20 min. Then, visible changes were noted with increasing power and time. D-spacing length reduced by 1.01% at 50°C for treatment periods of 10 min, 20 min, and 30 min, and there was no obvious change at 60°C; the periodic structure disappeared after cooking for 20 min, when fibrils had become gelatinized at 70°C. Collagen fibrils became disorganized at pH 3, following acid-base soaking. The present study indicated that acid-base soaking had an outstanding effect on the ultrastructure of collagen fibrils, especially in an acidic environment in consideration of the special structure of collagen.

Optimization-Based Unstructured Meshing Algorithms for Simulation of Hydraulically and Naturally Fractured Reservoirs With Variable Distribution of Fracture Aperture, Spacing, Length, and Strike

Summary Multistage hydraulically fractured wells are applied widely to produce unconventional resource plays. In naturally fractured reservoirs, hydraulic-fracture treatments may induce complex-fracture geometries that one cannot model accurately and efficiently with Cartesian and corner-point grid systems or standard dual-porosity approaches. The interaction of hydraulic and naturally occurring fractures almost certainly plays a role in ultimate well and reservoir performance. Current simulation models are unable to capture the complexity of this interaction. Generally speaking, our ability to detect and characterize fracture systems is far beyond our capability of modeling complex natural-fracture systems. To evaluate production performance in these complex settings with numerical simulation, fracture networks require advanced meshing and domain-discretization techniques. This paper investigates these issues by developing natural-fracture networks with fractal-based techniques. After a fracture network is developed, we demonstrate the feasibility of gridding complex natural-fracture behavior with optimization-based unstructured meshing algorithms. Then we can demonstrate that one can simulate natural-fracture complexities such as variable aperture, spacing, length, and strike. This new approach is a significant step beyond the current method of dual-porosity simulation that essentially negates the sophisticated level of fracture characterization pursued by many operators. We use currently established code for fractal discrete-fracture-network (FDFN) models to build realizations of naturally fractured reservoirs in terms of stochastic fracture networks. From outcrop, image-log, and core analysis, it is possible to extract fracture fractal parameters pertaining to aperture, spacing, and length distribution, including center distribution as well as a fracture strike. Then these parameters are used as input variables for the FDFN code to generate multiple realizations of fracture networks mimicking fracture clustering and randomly distributed natural fractures. After incorporating hydraulic fractures, complex-fracture networks are obtained for further reservoir-domain discretization. To discretize the complex-fracture networks, a new mesh-generation approach is developed to conform to nonorthogonal and low-angle intersections of extensively clustered discrete-fracture networks with nonuniform aperture distribution. Optimization algorithms are adopted to reduce highly skewed cells, and to ensure good mesh quality around fracture tips, intersections, and regions of extensive fracture clustering. Moreover, local grid refinement is implemented with a predefined distance function to control cell sizes and shapes around and far away from fractures. Natural-fracture spacing, length, strike, and aperture distribution are explicitly gridded, thus introducing a new simulation approach that is far superior to dual-porosity simulation. Finally, initial sensitivity studies are performed to demonstrate both the capability of the optimization-based unstructured meshing algorithms, and the effect of aforementioned natural-fracture parameters on well performance. This study demonstrates how to incorporate a fractal-based characterization approach into the current work flow for simulating unconventional reservoirs, and most importantly solves several issues such as nonorthogonal intersections, extensive clustering, and nonuniform aperture distribution associated with domain discretization with unstructured grids for complex-fracture networks. The proposed meshing techniques for complex fracture networks can be easily implemented in existing preprocessing, unstructured mesh generators. The sensitivity study and the simulation runs demonstrate the importance of fracture characterization as well as uncertainties associated with naturally fractured reservoirs on well-production performance.

The Effect of Eccentricity of the Tool on the Surface Morphology of FSJ Joint

An attempt is made here to join 2024 aluminum alloy plate by friction stir joining (FSJ) using tools with different eccentricity. Joint surface morphology was observed, and the sizes of both arc line spacing and flash were measured. Furthermore, study the effect of eccentricity of the tool on the surface topography of FSJ joint and analyze the formation of the joint surface topography. It is found that, the space trajectory of long axis of shoulder which formed by the eccentricity of the tool determine the morphology of the arc lines; the ratio between the feed speed and the rotation speed determine the arc line spacing; length of time that long axis of shoulder squeeze the edge of the joint line in the advancing side and the retreating side determines the size of flash in both sides of the joint line. Arc lines were regularly distributed in the joint lines and there are also regular texture structure distributed in the flash of each side. The flash in the advancing side is less than the retreating side. Increasing the amount of eccentricity, it has litter effect on the arc line spacing but will destroy the arc lines morphology in the joint surface and promote the formation of filamentous flash structure in the both sides of the joint.