Investigation and Experiment on a Short Dump-Diffuser of the Combustor

ABSTRACT This paper is intended to introduce optimal geometrical parameter matching obtained by using water flow simulation on the box-type specimen and blasting tests on the sector-type specimen for the short dump-diffuser of an annular combustion chamber, sad some special problems occurring in practice, such as, the effects of the factors --the head of flame tube,inlet cap, inlet support strut, splitting flow cone, air drawn from the wall surface and inlet velocity profiles on diffuser performance and its flow status, the obtained results provide the foundation for its practical application

Water Conservation Service Assessment and Its Spatiotemporal Features in National Key Ecological Function Zones

In order to improve ecosystem service and protect nation ecology security, the government had designated lots of important ecosystem service protection areas, named national key ecological function zones (NKEFZ) in China. Water conservation service had been assessed with the help of multisource remote sensing data, and spatiotemporal features were analyzed from 2000 to 2014 in these ecological services zones. By assuming precipitation scenario as the constant, contribution for water conservation from human activities and climate change was analyzed, and result shows that, because of vegetation restoration by human activities, evapotranspiration increased obviously with the increase of the vegetation coverage. This could reduce the water conservation. However, actual annual increase of water conservation mainly comes from the increase of precipitation. Our analysis revealed that the choice of evaluation model played a decisive role in the reason analysis, which would affect the development of ecological policy

Fixing the Reference Frame for PPMXL Proper Motions Using Extragalactic Sources

We quantify and correct systematic errors in PPMXL proper motions using extragalactic sources from the first two LAMOST data releases and the Veron-Cetty & Veron Catalog of Quasars. Although the majority of the sources are from the Veron catalog, LAMOST makes important contributions in regions that are not well-sampled by previous catalogs, particularly at low Galactic latitudes and in the south Galactic cap. We show that quasars in PPMXL have measureable and significant proper motions, which reflect the systematic zero-point offsets present in the catalog. We confirm the global proper motion shifts seen by Wu, Ma, & Zhou (2011), and additionally find smaller-scale fluctuations of the QSO-derived corrections to an absolute frame. We average the proper motions of 158,106 extragalactic objects in bins of 3x3 degrees and present a table of proper motion corrections.Comment: Accepted for publication in RAA; 12 pages, 6 figures (Fig. 1 at reduced resolution); full table of corrections available in online journal, with arxiv ancillary files (as ASCII table), or by reques

Query-dominant User Interest Network for Large-Scale Search Ranking

Historical behaviors have shown great effect and potential in various prediction tasks, including recommendation and information retrieval. The overall historical behaviors are various but noisy while search behaviors are always sparse. Most existing approaches in personalized search ranking adopt the sparse search behaviors to learn representation with bottleneck, which do not sufficiently exploit the crucial long-term interest. In fact, there is no doubt that user long-term interest is various but noisy for instant search, and how to exploit it well still remains an open problem. To tackle this problem, in this work, we propose a novel model named Query-dominant user Interest Network (QIN), including two cascade units to filter the raw user behaviors and reweigh the behavior subsequences. Specifically, we propose a relevance search unit (RSU), which aims to search a subsequence relevant to the query first and then search the sub-subsequences relevant to the target item. These items are then fed into an attention unit called Fused Attention Unit (FAU). It should be able to calculate attention scores from the ID field and attribute field separately, and then adaptively fuse the item embedding and content embedding based on the user engagement of past period. Extensive experiments and ablation studies on real-world datasets demonstrate the superiority of our model over state-of-the-art methods. The QIN now has been successfully deployed on Kuaishou search, an online video search platform, and obtained 7.6% improvement on CTR.Comment: 10 page

Effects of intra-aortic balloon pump on cerebral blood flow during peripheral venoarterial extracorporeal membrane oxygenation support

BACKGROUND: The addition of an intra-aortic balloon pump (IABP) during peripheral venoarterial extracorporeal membrane oxygenation (VA ECMO) support has been shown to improve coronary bypass graft flows and cardiac function in refractory cardiogenic shock after cardiac surgery. The purpose of this study was to evaluate the impact of additional IABP support on the cerebral blood flow (CBF) in patients with peripheral VA ECMO following cardiac procedures. METHODS: Twelve patients (mean age 60.40 ± 9.80 years) received VA ECMO combined with IABP support for postcardiotomy cardiogenic shock after coronary artery bypass grafting. The mean CBF in the bilateral middle cerebral arteries was measured with and without IABP counterpulsation by transcranial Doppler. The patients provided their control values. The mean CBF data were divided into two groups (pulsatile pressure greater than 10 mmHg, P group; pulsatile pressure less than 10 mmHg, N group) based on whether the patients experienced cardiac stun. The mean cerebral blood flow in VA ECMO (IABP turned off) alone and VA ECMO with IABP support were compared using the paired t test. RESULTS: All of the patients were successfully weaned from VA ECMO, and eight patients survived to discharge. The addition of IABP to VA ECMO did not change the mean CBF (251.47 ± 79.28 ml/min vs. 251.30 ± 79.47 ml/min, P = 0.96). The mean CBF was higher in VA ECMO alone than in VA ECMO combined with IABP support in the N group (257.68 ± 97.21 ml/min vs. 239.47 ± 95.60, P = 0.00). The addition of IABP to VA ECMO support increased the mean CBF values significantly compared with VA ECMO alone (261.68 ± 82.45 ml/min vs. 244.43 ± 45.85 ml/min, P = 0.00) in the P group. CONCLUSION: These results demonstrate that an IABP significantly changes the CBF during peripheral VA ECMO, depending on the antegrade blood flow by spontaneous cardiac function. The addition of an IABP to VA ECMO support decreased the CBF during cardiac stun, and it increased CBF without cardiac stun

Hierarchical Liouville-space approach for accurate and universal characterization of quantum impurity systems

A hierarchical equations of motion (HEOM) based numerical approach is developed for accurate and efficient evaluation of dynamical observables of strongly correlated quantum impurity systems. This approach is capable of describing quantitatively Kondo resonance and Fermi liquid characteristics, achieving the accuracy of latest high-level numerical renormalization group approach, as demonstrated on single-impurity Anderson model systems. Its application to a two-impurity Anderson model results in differential conductance versus external bias, which correctly reproduces the continuous transition from Kondo states of individual impurity to singlet spin-states formed between two impurities. The outstanding performance on characterizing both equilibrium and nonequilibrium properties of quantum impurity systems makes the HEOM approach potentially useful for addressing strongly correlated lattice systems in the frame work of dynamical mean field theory.Comment: 5 pages, 4 figures, to appear in PR

Improving the efficiency of small-scale wastewater treatment by pneumatic agitation

Small-scale anaerobic and aerobic systems for wastewater treatment suffer relatively low efficiencies due primarily to a lack of mechanical agitation/mixing. Here, a pneumatic agitation system was designed by installing a U-tube between the anaerobic and anoxic units, pumping air to the closed headspace of the anaerobic unit and releasing the pressurized air through the U-tube to create turbulence of the fluid. Computational Fluid Dynamics (CFD) simulation and fluid tracer trial were used to describe the fluid status in a lab-scale system (13 L). The results demonstrated that a continuous 5-cycle pneumatic agitation achieved a complete mixing of the static fluid. The retention time factor () and short-circuiting flow coefficient (/HRT) were increased from 0.93 to 1.14 and 0.02 to 0.27, respectively, indicating that pneumatic agitation significantly reduced dead zone and short-circuiting flow. A prototype at a treatment capacity of 300 L/d was installed in the North-East suburb of Beijing (40.15° N, 116.95° E) to treat rural household wastewater consisting of 630–1200 mg/L chemical oxygen demand and 20–45 mg/L total nitrogen. The field test was monitored in a period of 75 days from September to November 2018. The average removal rate for COD and TN was 96% and 92%, respectively by 10 times/h pneumatic agitation as compared to 49% and 45% without pneumatic agitation. The pneumatic agitation provides a low cost, easy operation and maintenance and efficient means for small-scale domestic wastewater treatment