Research on rational layout of strut arms of tainter gate in vertical frame

The overall stability of hydraulic tainter steel gate decrease seriously, and they are caused by improper structure layout of the two-way eccentric compression of struts. Chinese and American specification method, structural mechanics method and finite element method are respectively used to study rational structural layout of strut arms in vertical frame. First of all, a unified method for rational layout of struts of tainter gate in vertical frame is deduced by using structural mechanics method that simplifies curve girder as straight girder on the basis of zero rotation in vertical girder. Second, rational layouts of struts were researched by utilizing spatial finite element method according to zero rotation in vertical girder. The 756 groups rational layout results of the above three methods with different water heads, different number of struts and different unit stiffness ratios were researched. The differences of struts stress and material dosages of various rational layout methods were evaluated. From the point of view of the forces of tainter gate struts in vertical frame, as the results shown, the layouts of struts by Chinese and American specification method, straight beam method and finite element method are large eccentric compression, small eccentric compression and axial compression respectively. The layout of struts with specification method in lower head is quite different from straight beam method and finite element method, and the layouts of deep water head with straight beam method and finite element method are tend to be consistent. Unit stiffness ratio between vertical girder and strut has little effect on layout of tainter gate struts, but has a great influence on material dosages of tainter gate. Compared with specification method, layout of tainter gate with two struts and three struts by using straight beam method and finite element method can improve stability of struts and save materials of overall tainter gate structure, and the material saving rates of tainter gate with two struts and three struts with finite element method are respectively [32.63, 47.58] (%) and [21.61, 30.01] (%). Rational layout concise charts of tainter gate with two struts and three struts by specification method, straight beam method and finite element method are given, which can be used directly for projects designs. Compared with specification method, the layout of struts of straight beam method and finite element method is not only security and economy, but also method and mechanics concept are simple, which can provide the theoretical basis for specification revision of Chinese and American.Peer Reviewe

Design and Evaluation of Automated, Continuous Culture Techniques for Brachionus rotundiformis

A 40-L recirculating rotifer turbidostat (RRT) pilot system consisting of a rotifer reactor, biofilter, foam fractionator, feed container, harvester, and two air-lift pumps was designed to produce B. rotundiformis, a small (S-type) rotifer, that is increasingly demanded for production of small-gape marine finfish larvae. The system’s automatic monitoring (turbidity, pH, conductivity and temperature) and controlling (turbidity, pH, feeding and harvesting) were performed by a Rugid™ computer. A 4 (temperature) x 3 (salinity) study indicated that a 30oC/15 ppt treatment is the most favorable to the growth of B. rotundiformis. Under these conditions, the effect of harvest rate on rotifer system productivity was investigated with a feed ration of 1.3x105 cells Nannochloropsis oculata rot-1 d-1. Three 33-40 d pilot trials (mean stocking density: 742-946 rot mL-1) showed significant improvements in the daily rotifer harvest (1.68, 3.70 to 5.89 million rot d-1) and system volumetric productivity (0.09, 0.20 to 0.32 million rot L-1 d-1) with the increasing rotifer harvest rate (0.12, 0.21 to 0.37 d-1). Pilot trials demonstrated that the designed system functions in ammonia removal (mean TAN \u3c 0.15 mg N L-1), foam/solids reduction, continuous harvesting, pH controlling (pH ≥ 8.0), and culture stability. The Monod constants for B. rotundiformis fed N. oculata were determined using non-linear regression and Lineweaver-Burk plots. A linear equation between μmax and harvest rate (H, 0.12-0.37 d-1) was introduced to modify the Monod equation. A mechanistic model was developed for the designed RRT system and solved using STELLA®. The RRT model was calibrated with three datasets. The economic analyses were compared between 40-L and up-scaling 1-m3 systems at 103 rot mL-1 stocking level. The production cost for one million rotifers was reduced from $3.01 to$0.70 for this volume up-scaling. It lowers to $0.14 for further five-time density up-scaling. Model simulations indicated a harvest rate of 0.35 d-1 for a stable rotifer production under the Pilot Trial 3 scenario, although 0.60-1.10 d-1 could achieve the maximum productivity. The rotifer economic model can function as a useful management tool

Entropy Generation of Secondary Flow in a Turning Passage with Different Boundary Layer Characteristics

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).The development of secondary flow along a curved channel is a fundamental flow phenomenon occurring in a wide range of engineering applications, including turbomachinery, aerospace, heating, ventilation, air conditioning, etc. The underlying flow physics about end-wall secondary flows has been well-documented in the open literature, while the interaction between a secondary flow and a side-wall boundary layer, which is critical to the aerothermal performance of a side-wall surface, has not been comprehensively studied. In this study, the entropy generation of secondary flow and the interaction between an end-wall passage vortex and a side-wall boundary layer were numerically investigated by Reynolds-averaged Navier–Stokes (RANS) CFD for a 90° curved channel. The transportation effect of secondary flow and the generation mechanism of an induced vortex pair on the side wall is reported. It was also found that the growth of the secondary flow can be suppressed due to the displacement effect of the side-wall boundary layer. Furthermore, it was found that the interaction between a secondary flow and a side-wall boundary layer provides a suppression effect on side-wall boundary layer separation.Peer reviewe

Economic Burden for Lung Cancer Survivors in Urban China.

BackgroundWith the rapid increase in the incidence and mortality of lung cancer, a growing number of lung cancer patients and their families are faced with a tremendous economic burden because of the high cost of treatment in China. This study was conducted to estimate the economic burden and patient responsibility of lung cancer patients and the impact of this burden on family income.MethodsThis study uses data from a retrospective questionnaire survey conducted in 10 communities in urban China and includes 195 surviving lung cancer patients diagnosed over the previous five years. The calculation of direct economic burden included both direct medical and direct nonmedical costs. Indirect costs were calculated using the human capital approach, which measures the productivity lost for both patients and family caregivers. The price index was applied for the cost calculation.ResultsThe average economic burden from lung cancer was $43,336 per patient, of which the direct cost per capita was$42,540 (98.16%) and the indirect cost per capita was $795 (1.84$30,277 per capita, which accounted for 171% of the household annual income, a percentage that fell to 107% after subtracting the compensation from medical insurance.ConclusionsThe economic burden for lung cancer patients is substantial in the urban areas of China, and an effective control strategy to lower the cost is urgently needed

MaxViT: Multi-Axis Vision Transformer

Transformers have recently gained significant attention in the computer vision community. However, the lack of scalability of self-attention mechanisms with respect to image size has limited their wide adoption in state-of-the-art vision backbones. In this paper we introduce an efficient and scalable attention model we call multi-axis attention, which consists of two aspects: blocked local and dilated global attention. These design choices allow global-local spatial interactions on arbitrary input resolutions with only linear complexity. We also present a new architectural element by effectively blending our proposed attention model with convolutions, and accordingly propose a simple hierarchical vision backbone, dubbed MaxViT, by simply repeating the basic building block over multiple stages. Notably, MaxViT is able to "see" globally throughout the entire network, even in earlier, high-resolution stages. We demonstrate the effectiveness of our model on a broad spectrum of vision tasks. On image classification, MaxViT achieves state-of-the-art performance under various settings: without extra data, MaxViT attains 86.5\% ImageNet-1K top-1 accuracy; with ImageNet-21K pre-training, our model achieves 88.7\% top-1 accuracy. For downstream tasks, MaxViT as a backbone delivers favorable performance on object detection as well as visual aesthetic assessment. We also show that our proposed model expresses strong generative modeling capability on ImageNet, demonstrating the superior potential of MaxViT blocks as a universal vision module. We will make the code and models publicly available

The multichannel discharge plasma synthetic jet actuator

The plasma synthetic jet actuator (PSJA) is a flow control device capable of generating high speed pulsed jet. However, the performance of conventional PSJA is restricted by low discharge efficiency and small control area, because one power supply only drives one electrode couple. The present work is to propose a new concept of multichannel discharge plasma synthetic jet actuator (MD-PSJA), which is driven by single power supply. The new MD-PSJA has two types, namely the multi-electrode PSJA and the multi-PSJA array. These two types of MD-PSJA are examined experimentally. The multi-electrode PSJA containing 11-electrode PSJA is first studied. Comparison with standard 2-electrode PSJA reveals that the discharge efficiency and jet velocity increase 200% and 47% respectively under the same input energy and discharge voltage. The multi-PSJA array is later evaluated. One power supply is found to be able to drive an array of 12 PSJAs, resulting in 6 times affected area and 64% jet velocity of a conventional PSJA. The proposed MD-PSJA is finally concluded an improved active flow control actuator in high speed applications