Numerical Simulation and Experiment of Hydraulic Loss of Two-Stage Flap Valves

As a type of flap valve evolved from integral flap valve, two-stage flap valve has the advantages of large opening angle, small hydraulic loss and small impact force on the flap valve seat when the flap valve is closed. In order to analyze and study the hydraulic loss characteristics of the two-stage flap valve, this paper takes a pump station as an example. Based on theoretical analysis, combined with numerical simulation and model test, the hydraulic loss of two-stage flap valve is studied, and the relationship between hydraulic loss and pump station flow is obtained. According to the test results, the hydraulic loss of two-stage flap valve increases with the increase of flow rate under the same opening angle of flap valve. Under the same flow condition, the larger the opening angle of the flap valve is, the smaller the hydraulic loss of the two-stage flap valve is. When the opening angle of the upper flap valve is greater than 46° and the opening angle of the lower flap valve is greater than 64°, the hydraulic loss is less than 70mm and tends to be stable. The influence of hydraulic loss on the performance of pump device is gradually weakened. The relationship between hydraulic loss and flow of two-stage flap valve no longer satisfies the relationship of square under the constant opening angle. Moreover, the larger the opening angle of the two-stage flap valve is, the greater the relationship between hydraulic loss and flow is. Compared with the integral flap valve, the two-stage flap valve has better structural form and hydraulic characteristics, and has little influence on the performance of the pump device, which can provide reference for the application of the two-stage flap valve in the pump station.

Design and Application of Spiral Wound Gasket Sealing for Big Opening Flange for High Temperature and Pressure Vessel

Metallic spiral-wound gasket sealing are generally applicable for the service conditions, which are subject to the periodic temperature and pressure changes, shocks or vibrations. The nominal size of the largest spiral wound gasket of flanges is according to the provisions of HG/T 20631; those more than this specification are in the scope of non-standard parts, which require customization and manufacturing. This paper aims for introducing the successful experience of the first application of customized for non-standard spiral-wound gasket sealing of the large opening flange used for pressure vessel which bears high temperature and high pressure. The paper demonstrated the basic principle and critical points for the design and application of customized non-standard spiral-wound gasket sealing for the large opening flange and provided the valuable reference of actual application experience for the design and manufacturing of similar components. This paper presents the experiences summary in the study field and provides valuable reference of actual application experience for the design and manufacturing of similar components.

Evaluation of Nutrient Foramen in Adult Dry Human Femur

BACKGROUND Nutrient foramen is a large opening that transfers the arteries that supply the bone to the bone cavity. During surgical procedures, it is very important to have precise and complete information about the location of the foramina to determine whether the fracture line passes close to the nutrient foramina. The purpose of this study was to determine the number and position of the femoral nutrient foramina together with morphometric measurements. METHODS A total of 93 dry adult femurs with unknown sexes were examined in this study. The direction, location and the total number of nutrient foramina of the femur were investigated by using an anthropometer (Lafayette instrument, Indiana). Also, foraminal index was calculated. RESULTS The analysis revealed that 28 (53.8 %) of the femurs with a single nutrient foramen were on the right side and 22 (53.7 %) were on the left side, respectively. Femurs with double nutrient foramina were 23 (44.2 %) and 18 (43.9 %) on right and left sides, respectively. Femurs with triple nutrient foramina were 1(1.9 %) and 1 (2.4 %) on right and left sides, respectively. The foraminal index of femurs was found as (41, 58 %) and (42, 23 %) on the right and left sides, respectively. The nutrient foramen was mostly 84 (90.3 %) located at the middle third of the femur. CONCLUSIONS The findings of this study provide information and details about nutrient foramen which have clinical importance, especially in surgical procedures like bone grafting and microsurgical vascularized bone transplantation. KEY WORDS Femur, Foraminal Index, Nutrient Artery, Nutrient Foramina

Odontossecção intermediária em retenção atípica de caninos inferiores

Two lower canines horizontally situated in the anterior mental region were removed. In order to minimize bone loss during teeth extraction it was used an intermediate tooth section technique. Sectioning allows central, crown and apical portions of the tooth to be removed through a not too large opening provided by bone removal.

Spaceborne infrared imagery for early detection of Weddell Polynya opening

Knowing when sea ice will open is crucial, notably for scientific deployments. This was particularly obvious when the Weddell Polynya, a large opening in the winter Southern Ocean sea ice, unexpectedly re-appeared in 2016. As no precursor had been detected, observations were limited to chance autonomous sensors, and the exact cause of the opening could not be determined accurately. We investigate here whether the signature of the vertical ocean motions or that of the leads, which ultimately re-open the polynya, are detectable in spaceborne infrared temperature before the polynya opens. From the full historical sea ice concentration record, we find 30 polynyas starting from 1980. Then, using the full time series of the spaceborne infrared Advanced Very High Resolution Radiometer, we determine that these events can be detected in the 2 weeks before the polynya opens as a reduction in the variance of the data. For the three commonly used infrared brightness temperature bands, the 15 d sum and 15 d standard deviation of their area median and maximum are systematically lower than the climatology when a polynya will open. Moreover, by comparing the infrared brightness temperature to atmospheric reanalysis, hydrographic mooring data, and autonomous profilers, we find that temporal oscillations in one band and the decrease in the difference between bands may be used as proxies for upwelling of warm water and presence of leads, respectively, albeit with caution. Therefore, although infrared data are strongly limited by their horizontal resolution and sensitivity to clouds, they could be used for studying ocean or atmosphere preconditioning of polynyas in the historical record.

Cryo-EM structure of the photosynthetic RC-LH1-PufX supercomplex at 2.8-Å resolution

The reaction center (RC)−light-harvesting complex 1 (LH1) supercomplex plays a pivotal role in bacterial photosynthesis. Many RC-LH1 complexes integrate an additional protein PufX that is key for bacterial growth and photosynthetic competence. Here, we present a cryo–electron microscopy structure of the RC-LH1-PufX supercomplex from Rhodobacter veldkampii at 2.8-Å resolution. The RC-LH1-PufX monomer contains an LH ring of 15 αβ-polypeptides with a 30-Å gap formed by PufX. PufX acts as a molecular “cross brace” to reinforce the RC-LH1 structure. The unusual PufX-mediated large opening in the LH1 ring and defined arrangement of proteins and cofactors provide the molecular basis for the assembly of a robust RC-LH1-PufX supercomplex and efficient quinone transport and electron transfer. These architectural features represent the natural strategies for anoxygenic photosynthesis and environmental adaptation.

Nanopore design for exceptional rectification of DNA translocation

Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performance. However, reproducible production of arrayed nanopores of predefined geometry is yet to demonstrate despite of numerous methods explored. Here, bowl-shape SSNPs combining unique properties of ultrathin membrane and tapering geometry are demonstrated. The bowl-SSNP upper opening is 100-120 nm in diameter, with the bottom opening reaching sub-5 nm. Numerical simulation reveals the formation of multiple electroosmotic vortexes (EOVs) originating from distributed surface charge around the pore-bowl. The EOVs determine, collaboratively with electrophoretic force, how nanoscale objects translocate the bowl-SSNPs. Exceptional rectification with higher frequencies, longer duration and larger amplitude is found when DNA strands translocate downwards from the upper large opening than upwards from the bottom smallest restriction. The rectification is a manifestation of the interplay between electrophoresis and electroosmosis. The resourceful silicon nanofabrication technology is ingeniously shown to enable innovative nanopore designs targeting unprecedented sensor applications.

Finite element analysis of reinforced concrete deep beam with large opening

Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.