WATER HAMMER IN PIPELINE WITH DIFFERENT CHARACTERISTICS OF VALVE CLOSING AND UNSTEADY WALL FRICTION

This paper presents an analytical investigation of water hammer pressure variation in a reservoir-pipe-valve system. Laplace transform method is used to get the analytical solutions for different characteristics of the valve closing. Specifically, sudden valve closing and piecewise linear closing are used, the latter can be treated as approximated arbitrary characteristics of valve closing. Unsteady wall friction is also included. The new solutions compare well with the previous experimental data. The results show that this solution is suitable for water hammer with laminar and low Reynolds number turbulent unsteady flow. The effects of different characteristics of the valve closing on the water hammer pressure variations are also studied. This solution can be a better choice for optimization of valve closing to reduce the maximum water hammer pressure

Identification of Balanced Chromosomal Rearrangements Previously Unknown Among Participants in the 1000 Genomes Project: Implications for Interpretation of Structural Variation in Genomes and the Future of Clinical Cytogenetics

Purpose Recent studies demonstrate that whole-genome sequencing (WGS) enables detection of cryptic rearrangements in apparently balanced chromosomal rearrangements (also known as balanced chromosomal abnormalities, BCAs) previously identified by conventional cytogenetic methods. We aimed to assess our analytical tool for detecting BCAs in The 1000 Genomes Project without knowing affected bands. Methods: The 1000 Genomes Project provides an unprecedented integrated map of structural variants in phenotypically normal subjects, but there is no information on potential inclusion of subjects with apparently BCAs akin to those traditionally detected in diagnostic cytogenetics laboratories. We applied our analytical tool to 1,166 genomes from the 1000 Genomes Project with sufficient physical coverage (8.25-fold). Results: Our approach detected four reciprocal balanced translocations and four inversions ranging in size from 57.9 kb to 13.3 Mb, all of which were confirmed by cytogenetic methods and PCR studies. One of DNAs has a subtle translocation that is not readily identified by chromosome analysis due to similar banding patterns and size of exchanged segments, and another results in disruption of all transcripts of an OMIM gene. Conclusions: Our study demonstrates the extension of utilizing low-coverage WGS for unbiased detection of BCAs including translocations and inversions previously unknown in the 1000 Genomes Project

CHECKING THE ACCURACY OF LABORATORY TESTS

This paper presents an analytical investigation of water hammer pressure variation in a reservoir-pipe-valve system. Laplace transform method is used to get the analytical solutions for different characteristics of the valve closing. Specifically, sudden valve closing and piecewise linear closing are used, the latter can be treated as approximated arbitrary characteristics of valve closing. Unsteady wall friction is also included. The new solutions compare well with the previous experimental data. The results show that this solution is suitable for water hammer with laminar and low Reynolds number turbulent unsteady flow. The effects of different characteristics of the valve closing on the water hammer pressure variations are also studied. This solution can be a better choice for optimization of valve closing to reduce the maximum water hammer pressure

What determines rail transit passenger volume? Implications for transit oriented development planning

Transit oriented development (TOD) has been an important topic for urban transportation planning research and practice. This paper is aimed at empirically examining the effect of rail transit station-based TOD on daily station passenger volume. Using integrated circuit (IC) card data on metro passenger volumes and cellular signaling data on the spatial distribution of human activities in Shanghai, the research identifies variations in ridership among rail transit stations. Then, regression analysis is performed using passenger volume in each station as the dependent variable. Explanatory variables include station area employment and population, residents’ commuting distances, metro network accessibility, status as interchange station, and coupling with commercial activity centers. The main findings are: (1) Passenger volume is positively associated with employment density and residents’ commuting distance around station; (2) stations with earlier opening dates and serving as transfer nodes tend to have positive association with passenger volumes; (3) metro stations better integrated with nearby commercial development tend to have larger passenger volumes. Several implications are drawn for TOD planning: (1) TOD planning should be integrated with rail transit network planning; (2) location of metro stations should be coupled with commercial development; (3) high employment densities should be especially encouraged as a key TOD feature; and (4) interchange stations should be more strategically positioned in the planning for rail transit network

Efficient and Accurate 3-D Numerical Modelling of Landslide Tsunami

High-speed and accurate simulations of landslide-generated tsunamis are of great importance for the understanding of generation and propagation of water waves and for prediction of these natural disasters. A three-dimensional numerical model, based on Reynolds-averaged Navier–Stokes equations, is developed to simulate the landslide-generated tsunami. Available experiment data is used to validate the numerical model and to investigate the scale effect of numerical model according to the Froude similarity criterion. Based on grid convergence index (GCI) analysis, fourteen cases are arranged to study the sensitivity of numerical results to mesh resolution. Results show that numerical results are more sensitive to mesh resolution in near field than that in the propagation field. Nonuniform meshes can be used to balance the computational efficiency and accuracy. A mesh generation strategy is proposed and validated, achieving an accurate prediction and nearly 22 times reduction of computational cost. Further, this strategy of mesh generation is applied to simulate the Laxiwa Reservoir landslide tsunami. The results of this study provide an important guide for the establishment of a numerical model of the real-world problem of landslide tsunami

Numerical Simulation of Effects of River Reconstruction on Flooding: A Case Study of the Ba River, China

The local reconstruction of river channels may pose obstacles of flood flow, local eddy currents, or high flow velocity which pose potential threats to human life and infrastructures nearby. In the design of such projects, the effects of local reconstruction of the river channel on flooding are often evaluated by the one-dimensional method, which is based on the formula of one-dimensional nonuniform flow. In this study, a two-dimensional hydrodynamic model based on shallow water equations is employed to investigate the impacts of river reconstruction on flooding in the Ba River, China. The finite volume method and an unstructured triangular mesh are used to solve the governing equations numerically. The numerical model is validated by comparison with the results of a physical model of 1 : 120 scale. The backwater effects and impacts of flood flow fields under two flood frequencies are analyzed by comparing the numerical results before and after local reconstruction. The results show that the backwater length under both 10-year and 100-year floods can be reached up to the upstream boundary of the computational domain. However, the maximum water level rises are limited, and the levees in this river channel are safe enough. The flow velocity fields under both floods are changed obviously after local reconstruction in the Ba River. Areas with the potential for scour and deposition of the river bed are also pointed out. The findings of this study are helpful for the evaluation of flood risks of the river

Progress in analytical modeling of water hammer

Analytical formulas for laminar water hammer in horizontal pipes were extended and simplified into a compact mathematical form based on dimensionless parameters: dimensionless time, water hammer number, etc. Detailed treatment of turbulent water hammer analytical solutions is beyond the scope of this paper. In the Muto and Takahashi solution, novel Laplace and time domain formulas for flow velocity and wall shear stress were developed. A series of comparative studies of unified analytical solutions with numerical solutions and the results of measurements were carried out. The study shows that models that account for the frequency-dependent nature of hydraulic resistance agree very well with experimental results over a wide range of water hammer numbers Wh, particularly when Wh ≤ 0.1

Recent progress on organic donor-acceptor complexes as active elements in organic field-effect transistors

Recently, organic donor–acceptor complexes (co-crystals) have been strongly explored as active elements in organic field-effect transistors (OFETs) due to their tunable energy level and different stacking modes. The performance of co-crystal-based FETs can be enhanced through the design and synthesis of novel complexes, the control of the self-assembling morphology of co-crystals on substrates, and the optimization of the fabrication conditions of devices. In this review, we will summarize the recent progress on the methods to prepare donor (D)–acceptor (A) co-crystals and their films, present their structure–property relationships, and discuss their potential applications in OFETs according to the co-crystals with different acceptors, namely, (a) tetracyanoquinodimethane (TCNQ) and derivatives; (b) fullerene derivatives (such as C60 and C70); and (c) naphthalenediimide and perylenediimide derivatives. Moreover, co-crystal-based solid solutions and their FET performance are also mentioned.MOE (Min. of Education, S’pore

Copper-induced injectable hydrogel with nitric oxide for enhanced immunotherapy by amplifying immunogenic cell death and regulating cancer associated fibroblasts

Background Immunogenic cell death (ICD) induced by different cancer treatments has been widely evaluated to recruit immune cells and trigger the specific antitumor immunity. However, cancer associated fibroblasts (CAFs) can hinder the invasion of immune cells and polarize the recruited monocytes to M2-type macrophages, which greatly restrict the efficacy of immunotherapy (IT). Methods In this study, an injectable hydrogel induced by copper (Cu) has been designed to contain antibody of PD-L1 and nitric oxide (NO) donor. The therapeutic efficacy of hydrogel was studied in 4T1 cells and CAFs in vitro and 4T1 tumor-bearing mice in vivo. The immune effects on cytotoxic T lymphocytes, dendritic cells (DCs) and macrophages were analyzed by flow cytometry. Enzyme-linked immunosorbent assay, immunofluorescence and transcriptome analyses were also performed to evaluate the underlying mechanism. Results Due to the absorbance of Cu with the near-infrared laser irradiation, the injectable hydrogel exhibits persistent photothermal effect to kill cancer cells. In addition, the Cu of hydrogel shows the Fenton-like reaction to produce reactive oxygen species as chemodynamic therapy, thereby enhancing cancer treatment and amplifying ICD. More interestingly, we have found that the released NO can significantly increase depletion of CAFs and reduce the proportion of M2-type macrophages in vitro. Furthermore, due to the amplify of ICD, injectable hydrogel can effectively increase the infiltration of immune cells and reverse the immunosuppressive tumor microenvironment (TME) by regulating CAFs to enhance the therapeutic efficacy of anti-PD-L1 in vivo. Conclusions The ion induced self-assembled hydrogel with NO could enhance immunotherapy via amplifying ICD and regulating CAFs. It provides a novel strategy to provoke a robust antitumor immune response for clinical cancer immunotherapy. Graphical Abstrac