利用浮力富集乏风瓦斯的可行性研究

对于开采低渗透难抽采煤层的高瓦斯矿井,因抽采浓度低而难以利用,现场有利用浮力富集乏风中瓦斯的设想,本文研究其可行性。现场试验表明,瓦斯浓度沿着高度方向差别很小,不存在实际意义上的富集。理论分析认为,离析态的瓦斯在浮力作用下可能产生积聚,但积聚不是瓦斯富集而是稀释;气体自发的扩散和通风,使风流中的瓦斯由离析态迅速转变为非离析态,非离析态瓦斯在重力场中的分离程度可以忽略不计。

Fourier-shape-based reconstruction of rock joint profile with realistic unevenness and waviness features

Rock joint shape characteristics,waviness and unevenness play essential but distinct roles in shear mechanism of rock joints.This study presents a novel method to generate virtual rock joint profiles with realistic waviness and unevenness features.Firstly,joint profiles are obtained by 3D laser scanning device.Secondly,quantification of waviness and unevenness is conducted by traditional method,including digital filtering technique and roughness parameter RL.Thirdly,the discrete Fourier transform(DFT)method is employed to analyze the joint outlines.Two representative Fourier shape descriptors(D3,D8)for characterization of waviness and unevenness are suggested.Then,the inverse discrete Fourier transform(IDFT)is adopted to reconstruct the joint profiles with random values of phase angles but prescribed amplitudes controlled by D3 and D8.The traditional method is then applied to the reconstructed joint profiles to examine statistically the relationships between D3 and D8 and parameters RL of waviness and unevenness,respectively.The results show that larger D8 tends to result in larger waviness while higher D3 tends to increase unevenness.Reference charts for estimation of waviness and unevenness with different pairs of D3 and D8 are also provided to facilitate implementation of random joint reconstruction.

Isolation and rapid genetic characterization of a novel T4-like bacteriophage

Ubiquitous on earth,bacteriophages are the most abundant entities in every ecosystem,but human knowledge about them is still limited compared with that about other forms of organisms.To enrich human knowledge and promote the utilization of bacteriophages,it is necessary to isolate and characterize as many as possible different bacteriophages.Here we describe the isolation of a T4-like bacteriophage IME08 and a rapid method for its genetic characterization.With this method we easily cloned a few random fragments of the bacteriophage genome.Sequence analysis of these random clones showed that bacteriophage IME08 shared the highest sequence similarity with T4-like Enterobacteria phage T4（94%identity）,JS98（95% identity）,JS10（95%identity） and RB14（94%identity） respectively,which suggested that IME08 belonged to T4-like bacteriophage genus.

Energy Efficiency and Emissions Reduction Potential of China's Industrial Sector

Based on the total-factor energy efficiency framework,this paper calculates China's industrial energy efficiency and CO2 emissions reduction potential from 2000 to 2009 by utilizing the directional distance function and data envelopment analysis.The empirical results show that:China's industrial overall energy efficiency is relatively lower while the emis-sions reduction potential is relatively greater,given the optimum production frontier.Significant indus-trial disparities of energy efficiency and emissions reduction potential exist.Energy efficiency and emis-sions reduction potential significantly show different tendencies of industrial dynamic variation.This paper suggests the Chinese government impose differential carbon taxes,flexibly utilize carbon market mecha-nism,strengthen energy-saving technological R&D,promote the utilization of renewable energy,and strengthen environmental supervision and regulation,so as to improve China's industrial energy efficiency and reduce CO2 emissions.

Numerical and Experimental Research on the Influence of the Centrifugal Pumps Rotor Damage on Their Natural Frequency Response

The paper presents process of creating a centrifugal pump rotor model in CAD environment. Modeling of a virtual object was divided into two stages, modeling of the efficient pump and the simulated failure of one of the impeller＇s blades. Comparison of the results of the resonance frequency obtained from the model analysis, with those obtained from measurements on the actual object was shown. Measurements and simulations were conducted on the pump before and after the simulated damaged of the rotor. In order to verify the model the rotor of pump was weighted and compared with the masses of the respective components obtained from the virtual object. In the second stage genuine rotor was subjected to the experimental modal analysis.

Numerical Study on Particle Motions in Swirling Flows in a Cyclone Separator

The purpose of this study is to establish the high-accurate prediction method of particle separation in a cyclone separator. Numerical simulation of the swirling flows in a cyclone separator is performed by using a large eddy simulation （LES） based on a Smagorinsky model. The validity of the simulation and the complicated flow characteristics are discussed by comparison with experimental results. Moreover, particle motions are treated by a Lagrangian method and are calculated with a one-way method. A performance for particle separation is predicted from the results of the particle tracing. As results of our investigation, the influences of the inserted height of the outlet pipe on the performance for particle separation of cyclone separator are shown.

Nanopore-based sensing and analysis: beyond the resistive-pulse method

Solid-state nanopores are generally considered as an indispensable element in the research field of fundamental ion transport and molecular sensing. The im- provement in fabrication and chemical modification of the solid-state nanopores remains increasingly updated. During the last decades, numerous works have been reported on the nanopore-based sensing applications. More and more new analytical methods using nanopore-based devices are emerging. In this review, we highlight the recent progress on the analytical methods for the interdisciplinary and fast- growing area of nanopore research. According to the dif- ferent types of the electrical readout, whether it is steady- state ionic current or transient current fluctuation, the nanopore-based sensing and analysis can be generally di- vided into two categories. For the first type, the electrical readout shows a stable blockade or reopening of the nanopore conductance in the presence of target analytes, termed steady-state analysis, including the conductance change, electrochemical analysis, and two-dimensional scanning and imaging. The other type is based on the transient fluctuation in the transmembrane ionic current, termed transient-state analysis, including the noise analysis, transient ion transport, and transverse tunneling current. The investigation of solid-state nanopores for chemical sensing is just in its infancy. For further research work, not only new nanopore materials and chemical modifications are needed, but also other non-electric-based sensing techniques should be developed. We will focus our future research in the framework of bio-inspired, smart, multiscale interfacial materials and extend the spirit of binary cooperative complementary nanomaterials.

Non-equilibrium thermodynamics analysis and its application in interfacial mass transfer

Interfacial transfer plays an important role in multi-phase chemical processes. However, it is difficult to describe the complex interfacial transport behavior by the traditional mass transfer model. In this paper, we describe an interfacial mass transfer model based on linear non-equilibrium thermodynamics for the analysis of the rate of interfacial transport. The interfacial transfer process rate J depends on the interface mass transfer coefficient K, interfacial area A and chemical potential gradient at the interface. Potassium compounds were selected as model systems. A model based on linear non-equilibrium thermo-dynamics was established in order to describe and predict the transport rate at the solid-solution interface. Together with accurate experimental kinetic data for potassium ions obtained using ion-selective electrodes, a general model which can be used to describe the dissolution rate was established and used to analyze ways of improving the process rate.