CAPILLARY PRESSURE-SATURATION RELATIONSHIPS IN ROCK FRACTURE

Understanding and quantifying unsaturated flow through fractures in rocky slope is important for design and construction of drainage system in large-scale hydraulic engineering. The data of the hysteretic relationship between capillary pressure and water saturation are primary for simulating unsaturated flow in fractures and analyzing the stability of high rocky slope. The drainage and imbibition curves are measured for a single fracture in granite sample got at construction site of the Three Gorges Project (TGP). The method used in this study for measuring the capillary pressure-saturation relationship , under the conditions of no normal load to rock sample, is generally following the laboratory technique developed by Reitsma and Kueper. A distinct entry pressure, indicating rise to initiate nonwetting phase invasion, was observed. The drainage curve is found to be well represented by van Genuchten porous media capillary pressure function.     

A creep technique for monitoring the aging precipitation in Cu-Nb bainitic steels

A creep technique was applied on a Gleeble-1500 thermal simulator for monitoring the aging precipitation in ultra-low carbon steels containing various coppers. The aging hardening curve was obtained by the hardness testing. With the aid of an optical microscope and TEM, the microstructure and the aging precipitates were detected. The results indicate that when the precipitation occurs during the creep a plateau will appear on the creep curve; the left-hand and right-hand endings of the plateau correspond to the precipitation start （Ps） and finish （Pf） times, respectively. The Pf obtained from the creep curve coincides with the peak hardness time （tp） at the aging hardening curve. A precipitation-time-temperature （PTT） diagram of the steel can be obtained.     

生物光学材料—细菌视紫红质的性质及其分子电子学应用

生物光学材料──细菌视紫红质的性质及其分子电子学应用范文锦译张春平张存洲校Ｒ．ＲＢｉｒｇｅＰｈｏｔｏｐｈｙｓｉｃｓａｎｄｍｏｌｅｃｕｌａｒｅｌｅｃｔｒｏｎｉｃａｐｐｌｉｃａｔｉｏｎｓｏｆｔｈｅＲｈｏｄｏｐｓｉｎｓ一、引言本文评述了视紫红质的光物理性质...     

10Gb/s EML Module Based on Identical Epitaxial Layer Scheme

A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at －2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 1e－12 after transmission through 35km single mode fiber.     

Adsorption/desorption of toluene on a hypercrosslinked polymeric resin in a highly humid gas stream

In many sources of volatile organic compounds(VOCs), large amounts of water vapor come from the air and the reactors. The relative humidity(RH) of exhaust gas is normally N60% and is supersaturated. Maintaining the property of adsorbent on VOCs in a highly humid gas stream is a serious industrial problem. In this study, the adsorption/desorption behavior of toluene in a micro-mesoporous polymeric resin was investigated in a highly humid environment to explore the influence of abound water vapor on resin adsorption and regeneration.This resin could selectively adsorb toluene at an RH of 80%, and its adsorption property was unaffected by the presence of water vapor. In the case of humidity saturation, the resin displayed a high adsorption capacity at a moisture content of b30%. Therefore, the polymer resin is an excellent water-resistant adsorbent of VOCs.In the regenerative experiment, the resin maintained its original adsorption capability after four adsorption/desorption cycles of toluene purging with nitrogen gas at 120 °C. The resin exhibited excellent regeneration performance at high humidity.     

IDENTIFICATION OF DIESEL FRONT SOUND SOURCE BASED ON CONTINUOUS WAVELET TRANSFORM

Acoustic signals from diesel engines not only colitain useful information but also includeconsiderable noise components. To extract information for condition monitoring purposes the continu-ous wavelet transform (CWT)is used for the characterization of engine acoustics. The charasteristicsof the CWT in terms of the representation of short duration transient signals are reviewed firstlyWavelet selection and CWT implementation are then detailed. With the wavelet transform, the majorsoures of the exterior radiation sound of the engine front are surveyed. The research provides a reli-able basis for engineering practice to reduce vehicle sound level. Furthermore, the idenification resultsof the measured acoustic signals are compared with the identification results of the measured surfacevibration, and good agreement is observed.     

Electrohydrodynamic 3D printing of orderly carbon/nickel composite network as supercapacitor electrodes

Electrohydrodynamic(EHD)3D printing of carbon-based materials in the form of orderly networks can have various applications.In this work,microscale carbon/nickel(C-Ni)composite electrodes with con-trolled porosity have been utilized in electrochemical energy storage of supercapacitors.Polyacrylonitrile(PAN)was chosen as the basic material for its excellent carbonization performance and EHD print-ing property.Nickel nitrate(Ni(NO3)2)was incorporated to form Ni nanoparticles which can improve the conductivity and the capacitance performance of the electrode.Well-aligned PAN-Ni(NO3)2 com-posite structures have been fabricated and carbonized as C-Ni electrodes with the typical diameter of 9.2±2.1 μm.The porosity of the as-prepared C-Ni electrode can be controlled during the EHD process.Electrochemical results show the C-Ni network electrode has achieved a 2.3 times higher areal specific capacitance and 1.7 times higher mass specific capacitance than those of a spin-coated electrode.As such,this process offers a facile and scalable strategy for the fabrication of orderly carbon-based conductive structures for various applications such as energy storage devices and printable electronics.     

High-performance and broadband photodetection of bicrystalline(GaN)1-x(ZnO)x solid solution nanowires via crystal defect engineering

Crystal defect engineering is widely used as an effective approach to regulate the optical and opto-electronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic perfor-mance.In this work,a high-performance photodetector based on(GaN)1-x(ZnO)x solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light.The highest responsivity of the photodetector is as high as 60,86 and 43 A/W under the irradiation of 365 nm,532 nm and 650 nm,respectively.The corresponding response time is as fast as 170,320 and 160 ms.Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire.Moreover,the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast trans-mission channels for photo-generated carriers,reducing the recombination of photo-generated carriers.Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.     

Emerging porous nanosheets: From fundamental synthesis to promising applications

Metal-organic framework(MOF)nanosheets and covalent organic framework(COF)nanosheets as emerging porous materials nanosheets have captured increasing attention owing to their attractive properties originating from the advantages of large lateral size,ultrathin thickness,tailorable physiochemical environment,flexibility and highly accessible active sites on surface,and the applications of them have been explored in a wide range of fields.Although MOF and COF nanosheets own many similar properties,their applications in various fields show significant differences,probably due to their different compositions and bonding modes.Hence,we summarize the recent progress of MOF and COF nanosheets by comparative analysis on their advantages and limitations in synthesis and applications,providing a more profound and full-scale perspective for researchers or beginners to understand this field.Herein,the categories of preparation methods of MOF and COF nanosheets are firstly discussed,including top-down and bottom-up methods.Secondly,the applications of MOF and COF nanosheets for separation,catalysis,sensing and energy storage are summarized.Finally,based on current achievements,we put forward our personal insights into the challenges and outlooks on the synthesis,characterizations,and promising applications for future research of MOF and COF nanosheets.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples, in an automated grading device that uses convolutional neural networks to extract the size, color, texture, and roundness of an apple. The developed machine learning method uses the ability of learning representative features by means of a convolutional neural network (CNN), to determine suitable features of apples for the grading process. This information is fed into a one-to-one classifier that uses a support vector machine (SVM), instead of the softmax output layer of the CNN. In this manner, Yantai apples with similar shapes and low discrimination are graded using four different approaches. The fusion model using both CNN and SVM classifiers is much more accurate than the simple k-nearest neighbor (KNN), SVM, and CNN model when used separately for grading, and the learning ability and the generalization ability of the model is correspondingly increased by the combined method. Grading tests are carried out using the automated grading device that is developed in the present work. It is verified that the actual effect of apple grading using the combined CNN-SVM model is fast and accurate, which greatly reduces the manpower and labor costs of manual grading, and has important commercial prospects.