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Although inlet bent pipes are usually adopted due to limited installation space, the influences of different bend pipes on the inlet flow characteristics and performance of centrifugal compressors are still unclear. The numerical simulation of a centrifugal compressor is established and validated by experimental results with the case of a straight inlet pipe. Then, the internal flow characteristics of the centrifugal compressor with a 90-degree bent pipe (p90) and Z-shaped bent pipe (pz) are simulated and discussed. The results show that the adoption of two inlet bent pipes reduces the performance of the centrifugal compressor to a certain extent, which reduces more greatly with pz, with a maximum reduction of 6.82% in pressure ratio and 14.83% in efficiency, respectively. The pressure ratio and efficiency reduction of the centrifugal compressor both increase with the increment of distortion degree, which maintains the increasing trend as the flow rate increases, and the maximum distortion degree of p90 and pz reaches 0.0351 and 0.0479, respectively. The reduction degree of the pressure ratio shows a power–law relationship with the distortion degree, while the reduction degree of efficiency shows an exponential relationship with it. The flow characteristics at the outlet section of the inlet pipe affect the flow field distribution at the inlet of the impeller, and the distortion area ranges of the total pressure and axial velocity at the inlet of the impeller are near 72°–144° in the circumferential direction for p90, while those of pz are close to 108°–180° and 288°–360°. When the flow with a high distortion degree enters the impeller, a large area with high turbulent kinetic energy is formed in the downstream flow channel, resulting in an increase in the flow loss. [ABSTRACT FROM AUTHOR]

The continuing impact of local and global stressors on coral reefs worldwide is prompting the exploration of novel approaches aimed at mitigating and improving the bleak future projections for corals. Ex situ aquaculture has the potential to provide a standardized supply of source corals to support active intervention-based research endeavours as well as complementary reef restoration initiatives. To effectively achieve this supply of coral, however, ex situ aquaculture systems need to be able to efficiently maintain reproducing colonies, and have the capacity to support each coral life stage. We monitored the monthly reproduction of the brooding coral, Pocillopora acuta, for one year in two distinct aquaculture systems: a natural seawater-supplied flow-through system (FTS) and an artificial seawater-supplied recirculating aquaculture system (RAS). The coral colonies in both aquaculture systems showed relatively consistent reproduction over time (on average > 70% of all colonies reproducing each month) and maintained natural diel reproduction patterns even after 1 year of ex situ culture. Coral colony reproductive output and timing (i.e., lunar day of release) differed between aquaculture systems in some, but not all, seasons. Planulae released from colonies settled and grew to reproductive size after ~16 months of culture, resulting in the ex situ production of an F2 generation of a brooding coral within two distinct aquaculture systems. This demonstrated that the use of ex situ aquaculture could be directly applied to research, restoration, and conservation aimed at mitigating coral decline in a future marred by climate change and local impacts. [ABSTRACT FROM AUTHOR]

In the present study, structural model test using rectangular prismatic granite specimen 200 mm × 200 mm × 200 mm with a horizontal central circular hole of 78 mm diameter was conducted to investigate a rockburst process of borehole. Strain measurement system and high-speed camera were used to capture the rock responses during rockburst. Acoustic emission (AE) system was adopted to monitor the associated AE signals during the rockburst process, and to locate the positions of micro-cracks and subsequently quantitatively investigate the cracking mechanisms. In addition, scanning electron microscope (SEM) was also used to identify the micro-cracks of fragments. The experimental results indicate that rockburst process is characterized by significant spatial distribution and structural responses. As the circumferential stress of surrounding rocks increase, there are some local rockbursts interlacing at different regions of compressive stress concentration along the opening axis direction before overall rockburst. These local rockbursts continued to develop and coalesce, eventually forming overall rockburst. A local rockburst in the present test can be composed of several bursts and persist for a longer period of time than that in true-triaxial tests using rectangular prismatic specimen. Hoop effect, stress gradient around the opening, and last V-shaped bands were accurately simulated. According to AE analysis results, quiet period characterized by few AE hits with high amplitude and a sharp increase in AE energy can be used as an early warning signal for overall rockburst. The time and position of rockburst are related to the spatiotemporal distribution of AE event density, which can be used as a potential indicator for rockburst prediction. During the rockburst process, tensile cracks occupied most of the total micro-cracks, and tensile splitting dominated the failure process. Shear cracks due to tensile cracks interaction initiated at 67% of the spalling strength (tangential stress for spalling failure at the opening boundary) of the borehole. [ABSTRACT FROM AUTHOR]

Numerous methods for predicting γ-turns in proteins have been developed. However, the results they generally provided are not very good, with a Matthews correlation coefficient (MCC) ≤0.18. Here, an attempt has been made to develop a method to improve the accuracy of γ-turn prediction. First, we employ the geometric mean metric as optimal criterion to evaluate the performance of support vector machine for the highly imbalanced γ-turn dataset. This metric tries to maximize both the sensitivity and the specificity while keeping them balanced. Second, a predictor to generate protein shape string by structure alignment against the protein structure database has been designed and the predicted shape string is introduced as new variable for γ-turn prediction. Based on this perception, we have developed a new method for γ-turn prediction. After training and testing the benchmark dataset of 320 non-homologous protein chains using a fivefold cross-validation technique, the present method achieves excellent performance. The overall prediction accuracy Q can achieve 92.2% and the MCC is 0.38, which outperform the existing γ-turn prediction methods. Our results indicate that the protein shape string is useful for predicting protein tight turns and it is reasonable to use the dihedral angle information as a variable for machine learning to predict protein folding. The dataset used in this work and the software to generate predicted shape string from structure database can be obtained from anonymous ftp site freely. [ABSTRACT FROM AUTHOR]