Search

The hydration exothermic rate of fly ash concrete is significantly affected by the initial concreting temperature and water-binder ratio. Firstly, the adiabatic temperature rise and temperature rise rate of fly ash concrete at different initial concreting temperatures and water-binder ratios were obtained by a thermal test instrument; then, the effects of initial concreting temperature and water-binder ratio on the hydration kinetic parameters of the NG-I-D hydration process of fly ash concrete were analyzed by the theory of hydration kinetics; lastly, the effects of initial concreting temperature and water-binder ratio on chemically bound water and pore bulk of fly ash concrete during hydration were analyzed by applying a thermogravimetric analyzer and industrial CT scanning techniques. The results showed that the increase in initial concreting temperature and the decrease in water-binder ratio accelerated the rate of temperature rise, and the initial concreting temperature had a more significant effect than the water-binder ratio. During the hydration reaction, the I process was significantly influenced by the initial concreting temperature, and the D process was significantly influenced by the water-binder ratio; the content of bound water increased with the increase in water-binder ratio and age and the decrease in initial concreting temperature. The initial temperature had a significant effect on the growth rate of 1 to 3 days bound water, and the water-binder ratio had a more significant effect on the growth rate of 3 to 7 days bound water. The porosity was positively correlated with the initial concreting temperature and water-binder ratio and decreased with age, but 1 to 3 days was the key period of porosity change. Additionally, the pore size was also influenced by the initial concreting temperature and water-binder ratio.

In the present study, we used low-field nuclear magnetic resonance (LF-NMR) measurements and mercury intrusion porosimetry (MIP) to evaluate the influence of the water–binder (w/b) ratio, fly ash (FA) replacement and curing regimes on the pore structure of concrete. The main advantage of LF-NMR is that it is nondestructive and suitable for large concrete samples compared with other traditional methods, such as MIP, adsorption methods and scanning electron microscopy methods. Hence, the LF-NMR relaxometry method measures the pore structures that are closer to reality. The LF-NMR relaxation time, T2, represents the change in the pore structure during the hydration and hardening processes of concrete. The results showed that the T2 spectrum of the concrete sample was mainly composed of 3–5 signal peaks. Additionally, the w/b ratio, FA replacement and the curing regimes have significant effects on the T2 spectrum, porosity, and pore size distribution of concrete. In addition, the compressive strength of concrete has a close relationship with its pore structure. Based on the LF-NMR test results, the relationship between the compressive strength and the porosity, pore size distribution of concrete was established.

Self-restraint stress produced in early age is a matter of interest associated with cracking of concrete. Mesoscopic modelling nowadays is one of the effective approaches to investigate internal stresses, deformation, damage of concrete at much smaller scale. However, grid discretization and mesoscopic properties calibration are still challenging issues that prevent fast pre-processing and require extremely dense meshes for accurate solutions. In this paper, a thermo-mechanical model required only regular-element discretization is proposed by developing a diffuse meshing technique to analyze the evolution of self-restraint stress. Cross-scale numerical validations are carried out to calibrate the mesoscopic parameters, along with verifying the feasibility of the proposed model. Furthermore, the effect of simplified aggregate mesostructure on the thermo-mechanical behavior of concrete is evaluated through comparisons with the results obtained by considering complex-shaped aggregate using the proposed diffuse element model. The results show the thermo-mechanical mismatch between different components is the main reason for producing the self-restraint stress, and aggregate meso-structure have nonnegligible influence on the global response or local behavior.

In this paper, a novel numerical method for random generation of aggregates in concrete is presented. Compared with some other models, the aggregates model generated by this method offers a better approximation to the geometric shape of real aggregates and the target gradation. The research incudes that (1) a surface reconstruction method is developed first on the basis of the implicit T-spline surface algorithm through defining a modified knot vector, determining the off-set point locations and their sign distances, which aims at avoiding occurrence of unclosed curved surface or spurious sheets and reconstructing accurately the complex surface according to a set of scattered surface points of a gravel aggregate; (2) a sinusoidal generatrix function, of which the amplitude represents the aggregate size range and the period reflects the aggregate flatness, is proposed to auto-generate a set of scattered points on the surface of a gravel aggregate. Further modifications are made to improve the quality of the scattered points that agree well with the real crushed aggregate surface; (3) An efficient aggregate packing method is proposed by combining and modifying the “occupation and removal method” and the “layering disposition method” to improve the efficiency of aggregate packing; and (4) a MATLAB computing program for auto-generating aggregates in concrete is developed and validated by examples. The simulation results have demonstrated that the method presented in this paper can generate aggregates for any given mix proportions and gradations and the method can serve as an effective tool for numerical evaluation of mechanical properties of concrete materials.

In order to promote the work of prevention and management of coal mine water disaster in China, it took Panlong coal mine, Xiayukou coal mine and Xiangshan coal mine in Hancheng mining area as object of study, which were compared from 7 classification factors of hydrogeological type, time and scale of water inrush. Ordovician limestone water inrush and water inrush from old and empty areas were then thought out to be the major types of water disaster in Hancheng mining area.

The CAFE (Census of warm-hot intergalactic medium, Accretion, and Feedback Explorer) and LyRIC (Lyman UV Radiation from Interstellar medium and Circum-galactic medium) have been proposed to the space agencies in China respectively. CAFE was first proposed as a joint scientific CAS-ESA small space mission in 2015. LyRIC was proposed as the independent external payload operating on the Chinese Space Station (CSS) in 2019. Both missions are dedicated to mapping the Lyman UV emissions ( ionized oxygen (OVI) resonance lines at 103.2 and 103.8 nm, and Lyman series) for the diffuse sources either in our Galaxy or the circum-galactic mediums of the nearby galaxies. We present the primary science objectives, mission concepts, the enabling technologies, as well as the current status.

If the construction engineering contracted by the constructor has serious quality problems which the constructor fails to repair or refuses to repair, the constructor’s claim for liquidated damages for the progress payment for the engineering shall not be supported. In the case that one party does not claim for the interest on arrears of payment for the engineering, the people’s court cannot regard the party’s claim for liquidated damages for the progress payment for the engineering as the claim for interest on arrears of payment for the engineering, for default in paying liquidated damages for the progress payment for the engineering is a liability for breach of contract, while the interest on arrears of payment for the engineering is civil fruit. They are different in legal nature and function and should be distinguished.

In order to promote the work of prevention and management of coal mine water disaster in China, it took Panlong coal mine, Xiayukou coal mine and Xiangshan coal mine in Hancheng mining area as object of study. Methods of prevention and management of Ordovician limestone water inrush and water inrush from old and empty areas were put forward. Some examples were chosen to approve these methods’ practicability. At last, enhancing management of coal mine and improving stuffs’ comprehensive quality were proposed.

To reduce the alignment difficulty and achieve high diffraction efficiency, a self-aligned method for fabricating large-aperture multi-level Fresnel membrane optic is proposed. Using this method, the rigorous alignment is avoided during fabrication process and high diffraction efficiency is achieved. A 4-level Fresnel diffractive polyimide membrane optic in 200 mm diameter and 20 μm thickness was manufactured by this method, which exhibits about 63% diffraction efficiency into the +1 order. The thickness variation of the membrane has a RMS of 30 nm.

As a kind of slim shell structure flexibly based on its deformable foundation, high concrete arch dam exhibits remarkable spatial–time characteristics. In this paper, the Xiaowan Hydropower Project accommodating 294.5 m high double curvature arch dam is taken as example, to which the factor of time is introduced in the whole numerical simulation procedure. The dynamic inputting of the parameters related to the structural geometry and material properties (e.g. thermal, permeability, deformation/stress) following the construction progress is realized in an intension to establish a four-dimensional (spatial–time) numerical simulation procedure. The Digitized System of Xiaowan Arch Dam (DSXAD) is further formulated by the combination of the instrumentation system, the spatial–time simulation procedure, and the engineering judgments. The DSXAD has been working well in tracing the real working status of the dam during its construction period as well as service period. A series of difficult technical issues in the construction of the Xiaowan Dam are successfully solved with the help of the DSXAD. Through this practices important theoretical insights are achieved, which founds a new landmark for the high arch dam construction in China.

In this paper, we systematically investigate the morphological characteristics and evolution process of plasma induced pitting damage (PIPD) during the inductively coupled plasma (ICP) etching of fused silica with subsurface damage (SSD). Plasma induced pits are found to have uniform diameter as opposed to SSD induced pits. PIPD evolves differently in physical and reactive etching. In physical etching, the pit diameter increases linearly with etching time due to the etching of pit sidewall, while the depth remains constant. In CHF3 plasma, depth also increases with etching time. This is due to the redistribution of F-based etchant caused by the pit sidewall, which enhances the local etching rate at the pit bottom. The fact that with increasing etching time the diameter increases linearly but remains uniform implies that all the pits are generated at the same time. More particularly, the fitted line suggests that PIPD forms at the beginning of plasma process.

Near-field holography (NFH), with its virtues of precise critical dimensions and high throughput, has a great potential for the realization of soft x-ray diffraction gratings. We show that NFH with reflections reduced by the integration of antireflective coatings (ARCs) simplifies the NFH process relative to that of setups using refractive index liquids. Based on the proposed NFH with ARCs, gold-coated laminar gratings were fabricated using NFH and subsequent ion beam etching. The efficiency angular spectrum shows that the stray light of the gratings is reduced one level of magnitude by the suppression of interface reflections during NFH.

To reduce the cost and achieve high diffraction efficiency, a modified moire technique for fabricating a large-aperture multi-level Fresnel membrane optic by a novel design of alignment marks is proposed. The modified moire fringes vary more sensitively with the actual misalignment. Hence, the alignment accuracy is significantly improved. Using the proposed method, a 20 μm thick, four-level Fresnel diffractive polyimide membrane optic with a 200 mm diameter is made, which exhibits over 62% diffraction efficiency into the +1 order, and an efficiency root mean square of 0.051.

We designed and fabricated polarization-independent multilayer dielectric reflection gratings of 1300 line/mm for spectral beam combining. Because the designed grating has a duty cycle (or fill factor) much greater than 0.5, we used the lift-off process to invert a less-than-0.5 duty cycle photoresist mask to a greater-than-0.5 duty cycle chromium mask. Because the simultaneous polarization-independence and high-angular-dispersion requirements greatly reduce fabrication tolerance, we employed the end-point detection techniques to control accurately the duty cycle and groove depth of the grating profile to reach the design target. The measured polarization-averaged diffraction efficiency of the fabricated gratings was greater than 97% in the wavelength range of 1050 nm–1080 nm.

In this work, we introduce an optimum ICP etching technique that successfully removes the subsurface damage (SSD) layer of fused silica without causing plasma induced surface damage (PISD) or lateral etching of SSD. As one of the commonest PISD initiators, metal contamination from reactor chamber is prevented by employing a simple isolation device. Based on this device, a unique low-density pitting damage is discovered and subsequently eliminated by optimizing the etching parameters. Meanwhile etching anisotropy also improves a lot, thus preventing the lateral etching of SSD. Using this proposed technique, SSD layer of fused silica is successfully removed with a surface roughness of 0.23 nm.

The ion beam sputtering (IBS) of smooth mono-elemental Si with impurity co-deposition is extended to a pre-rippled binary compound surface of fused silica (SiO2). The dependence of the rms roughness and the deposited amount of Al on the distance from the Al source under Ar+ IBS with Al co-deposition was investigated on smooth SiO2, pre-rippled SiO2, and smooth Si surfaces, using atomic force microscopy and X-ray photoelectron spectroscopy. Although the amounts of Al deposited on these three surfaces all decreased with increasing distance from the Al target, the morphology and rms roughness of the smooth Si surface did not demonstrate a strong distance dependence. In contrast to smooth Si, the rms roughness of both the smooth and pre-rippled SiO2 surfaces exhibited a similar distance evolution trend of increasing, decreasing, and final stabilization at the distance where the results were similar to those obtained without Al co-deposition. However, the pre-rippled SiO2 surfaces showed a stronger modulation of rms roughness than the smooth surfaces. At the incidence angles of 60° and 70°, dot-decorated ripples and roof-tiles were formed on the smooth SiO2 surfaces, respectively, whereas nanostructures of closely aligned grains and blazed facets were generated on the pre-rippled SiO2, respectively. The combination of impurity co-deposition with pre-rippled surfaces was found to facilitate the formation of novel types of nanostructures and morphological growth. The initial ripples act as a template to guide the preferential deposition of Al on the tops of the ripples or the ripple sides facing the Al wedge, but not in the valleys between the ripples, leading to 2D grains and quasi-blazed grating, which offer significant promise in optical applications. The rms roughness enhancement is attributed not to AlSi, but to AlOxFy compounds originating mainly from the Al source.

A new and simple method is demonstrated to achieve size controllable nanochannels by using nanoimprint lithography and low-pressure thermal bonding methods. The flexible free-standing SU-8 allows the bonding of the nanochannels' pattern features at such a low pressure primarily because of ‘sequential’ bonding made possible by the bonding layer flexibility and the conformal contact made between the bonding layer and the structure layer in a large area. The simple geometrical argument shows that the height of the enclosed nanochannel can be determined by the depth of the cross-linked SU-8 trenches as well as by the initial thickness of the thin unexposed SU-8 layer. The height of the nanochannels can also be controlled by adjusting the ratio of the ridge width to the trench width on the SU-8 trenches. These simple relationships can serve as a guideline in choosing the parameters for SU-8 nanochannel fabrication.

The drawdown velocity of foundation pit water level in existing projects is mostly determined empirically, and the influence of water level drawdown velocity on the seepage field and stress field in the weir body is not fully considered. The water level change of the foundation pit is an important factor affecting the stability of the cofferdam. Therefore, it is of great practical significance to study the variation law of seepage field and stress-strain field of cofferdam during the pumping process of foundation pit, to accurately judge the stability of cofferdam slope and to formulate reasonable pumping and drainage scheme. Based on the 1th temporary earth-rock cofferdam of Yongning Water Conservancy Project, the nonlinear finite element method is used to calculate the spatial-temporal evolution of seepage field and stress-strain field of earth-rock cofferdam under different drawdown velocity of water level. The overall deformation of the cofferdam, the shear failure and instability characteristics of the slope, and the influence of water level changes on the stability of the cofferdam slope are analysed. The results show that the distribution of unsaturated zone and negative pore pressure zone is basically the same. The excessive water level drawdown velocity is easy to break the balance between the seepage field and the water level fall time, resulting in the rise of saturation line height and the increase of the upper bending rate. The effect of seepage control is weakened, and the stability of the slope is poor. The shear deformation of the cofferdam slope develops from the foot of the slope and extends to the crest of the cofferdam until it runs through. At the same time, local plastic deformation occurs at the foot of the outer stone slag berm, and the maximum deformation transits to the foot of the inner slope. Under the action of seepage force, the stability of the inner slope is always smaller than that of the outer one; the change of water level drawdown velocity is very sensitive to the stability of the slope, when the drawdown velocity is greater than the critical velocity, the stability of the slope decreases sharply. Combined with the characteristics of earth-rock cofferdam, on the basis of satisfying the stability of cofferdam, the drawdown velocity of water level should be controlled within 1.28m/d. The research results of the thesis have reference significance for the selection of pumping speed of foundation pit similar to earth-rock cofferdam.

In recent years, steel sheet pile cofferdam has been adopted in some hydropower reconstruction and extension projects because of its many advantages. However, due to insufficient understanding of the bearing mechanism of super-high cellular cofferdam and lack of Engineering experience, there is no exact method to accurately predict the deformation and failure forms of the cofferdam, and there is no perfect safety and economic design theory, which restricts its popularization and application. Taking the Tarbela 4th Extension Project as background, the mechanical behavior and stability evaluation of the cofferdam in 30m deep water during construction and operation are studied by FEM, and influence of structural form and parameters on deformation characteristics of key parts is analysed. Results show that the maximum interlock tension occurs near mudline or top of berm during high lateral load. Development distribution of shear deformation are more in line with the Kitajima Shoichi’ method. The overturning deformation of cell can be effectively restrained by embedment, the rotation point changes regularly with the increase of berm and embedment. The sliding surface in cell conforms to Hansen’s calculation theory, the position of rotation and change of base pressure are closer to the Japanese standard. With the stiffness loss, the change of interlock tension is similar to the damage of low carbon steel, the shear sliding surface is related to berm which above the top overturning deformation is the largest. Based on the stability of cofferdam, there are various combinations of berm height and embedded depth, which can reduce the quantity of embankment works and the cost of later maintenance. The research results are of reference significance for the design and construction of similar super-high steel sheet pile cofferdams.

Soft x-ray varied line spacing grating (VLSG), which is a vital optical element for laser plasma diagnosis and spectrometry analysis, is conventionally fabricated by holographic lithography or mechanical ruling. In order to overcome the issues of the above fabrication methods, a method based on electron beam lithography-near field lithography (EBL-NFH) is proposed to make good use of the flexibility of EBL and the high throughput of NFH. In this paper, we showed a newly designed soft x-ray VLSG with a central groove density of 3600 lines/mm, which is to be realized based on EBL-NFH. First, the optimization of the spatial distribution of line density and groove profile of the VLSG was shown. As an important element in NFH, a fused silica mask plays a key role during NFH in order to obtain a required line density of VLSG. Therefore, second, the transfer relationship of spatial distribution of line densities between fused silica mask and resist grating was investigated in different exposure modes during NFH. We proposed a formulation about the transfer of line density to design of the groove density distribution of a fused silica grating mask. Finally, the spatial distribution of line densities between the fused silica mask, which is to be fabrication by using EBL, was demonstrated.

With the development of micro- & nanofabrication technology, micro- & nanostructures have been widely used in many fields, including spectroscopy, coding, sensor, subwavelength element, etc. With phase masks realized by a combination of electron beam lithography (EBL), near field lithography (NFH) has great potential to fabricate versatile nanostructures, because it combines the advantages of both lithographic methods. Currently, subwavelength structures attract much attention due to their various functions, such as antireflection, polarization beam splitter and filter. In this presentation, aiming at reducing the interface reflection of a fused silica mask of NFH at a wavelength of 441.6 nm and incidence angles of either 0° or 32°. First, we will compare the difference of antireflection property of one-dimensional (1D) and two-dimensional (2D) subwavelength structures with line density of 3600 lines/mm by simulation. Then, the optimized 1D and 2D subwavelength structures with 3600 lines/mm will be fabricated by using EBL-NFH method. Finally, the antireflection property of these 1D and 2D subwavelength structures will be characterized at the wavelength of 441.6 nm.

A new method for controlling the groove profiles of diffraction gratings which changes the etching angle and etching time, meanwhile divides the etching area in the substrate into multi-layers to have a good approximation for the theory is introduced. We put forward a multi-layers etching model on the base of the ion bean sputtering (IBS) which can calculate the etching time and etching angle. We test the curved grooves profiles and get the optimizations for the number of the multi-layers, etching time and etching time in this model. Also a photoresist grating is applied for the etching experiment. The results indicate that the optimized parameters such as the number of the multi-layers result in a smaller root mean square deviation (RMSD) between the theory and the real etching result which show good agreement with the theoretical groove within the variation of ±6% of the etching rate. The simulation predictions and experimental results show that the multi-layers etching model to control the groove profiles of diffraction gratings is available.

Diffractive optical system can be a favorable choice for large-aperture space telescope to reduce the mass and size of image system. To meet the demand of large-aperture, high efficiency, lightweight diffractive optic for high resolution remote sensing, a 200 mm diameter, 20 μmthick, 4-level diffractive membrane fabricated is shown to have over 62% diffraction efficiency into the +1 order, with 0.051 efficiency RMS. Over 66% diffraction efficiency is achieved for a 100 mm aperture membrane, with 0.023 efficiency RMS. The membrane thickness uniformity control is discussed and 8 nm wave front error RMS is achieved in 100 mm diameter.

Structure effects of distributed feedback (DFB) gratings on lasing action have been investigated for detecting explosive vapors. For the first time, we have established the optimized profiles of the DFB grating, and given the theoretical path to design its structure for amplified spontaneous emission (ASE) of organic polymer films based on Bragg conditions. A poly(p-phenylene ethynylene) (PPE) film can realize detection of dinitrotoluene (DNT) vapors in 2 min with a reduced excitation threshold of 26 mJ cm(-2) by using a simple and common 405 nm laser.

Patterned ferromagnetic thin film shows promising applications in ultra-high density magnetic storage, magnetoresistive transducer, magnetic random access memory and many other devices. Since the performance of these devices is closely associated with the magnetic properties of the etched patterns, it is necessary to study the effects of freshly etched surface oxidation on the magnetic properties of the patterned microstructures. In the current work, were carried out an X-ray Magnetic Circular Dichroism (XMCD) study on a 50 nm Co0.9Fe0.1 continuous thin film and a related patterned Co0.9Fe0.1 grating structure etched with a 2 μm period. Based on the sum rules, the spin and orbital moments were calculated for these two samples, respectively. The results indicated that the spin and orbital moments of grating structure (1.34µB and 0.24µB, respectively) decreased 17.3% compared with the corresponding continuous film (1.62µB and 0.29µB, respectively). We proposed that the moment decreasing of the patterned grating structure was mainly caused by the etched surface oxidation during the pattern manufacture process. The oxidation ratio of Co element in the patterned grating structure is 14.4% calculated from X-ray absorption spectroscopy (XAS) measurement. Considering the oxidation ratio, we amend the spin and orbital moment of Co and the amended result is basically in accordance with that of continuous film, demonstrating that the difference of the spin and orbital moments between the sub-micron grating unit and the continuous film is really caused by the oxidation.

In this paper, we demonstrate a new and simple method to achieve ultrasmall nanochannels downing size to about 50nm with well-controlled dimensions in large area by using NIL and angled physical vapor deposition (PVD). The polymer SU-8 nanogratings substrate is fabricated using NIL. After NIL, oblique angle ion beam sputtering of silicon oxide was used, in a single step, to reduce the cross section of the SU-8 imprinted trenches and seal the channels at the same time. During this process, the sidewalls of any trench will shadow the evaporation and most of the silicon oxide film will be deposited on the sidewalls at the top of the trench, therefore, the shadow area will be protected and ultimately formed as sealed nanochannels on substrate. The advantage of this process is that the line width can be adjustable simply by controlling the deposition as well as the imprint depth, offering an alternative solution for high-resolution and low-cost fabrication of nanofluidic chip. The method is applicable for most substrates and cover layer, therefore, it provides a new way to produce size reduction and size controlling of nanopatterns for various material.

In this paper, we demonstrate a new method for fabrication centimetre-long, dense and vertical sidewalls silicon-on-insulator (SOI) mould using holographic method combine with crystallographic anisotropic etching. Holographic method can make narrow dense and multiple continuous lines in large area while crystallographic anisotropic etching could eliminate line-edge-roughness (LER) in sidewalls and make the sidewalls nearly atomic-scale smoothness. Therefore, the line width of the SOI mould will in a high uniformity and the sidewalls will be smooth and vertical over centimetre lengths. Compare to common NIL mould, the smooth and vertical sidewall of SOI mould provided an easier demoulding process after NIL. Multiple centimetre-long fluidic-channels with smooth and vertical sidewall fabricated by faithfully imprint of SU-8 and an optimised sealing process using free-standing SU-8 bonding film.

Fluorinated reduced graphene oxide (F-RGO) is prepared by CF4 plasma treatment of RGO. The fluorine (F) doping is confirmed by X-ray photoelectron spectroscopy and its content is directly related to the plasma exposure time. A modest p-doping effect of the fluorination is observed from the electrical measurements. It is found that the F-RGO is an even better substrate for surface enhanced Raman spectroscopy of molecules than RGO. The relative enhancement factor can be tuned by manipulating the F content in the F-RGO. The effect is attributed to the presence of the strong local electric field induced by the local dipoles of F-containing groups on the F-RGO surface. This shows that the formation of well-designed surface dipoles could be a general way to increase the chemical enhancement of molecular Raman spectra.

This paper reports a novel method for the fabrication of silver electrode with high resolution using transfer printing method. The resolution can reach to 30@mm with high electrical conductivity as we keep a large depth and micro-size particles of the silver. In the study, we prepare the mixture binder for silver paste to improve the property of transferring. The parameters of the transfer process, including paste properties, pressure and surface energy, are also studied. Silver fingers of 50@mm width and 20@mm depth has been successfully fabricated on polysilicon and fired at 600^oC in Tube Furnace. The electrical conductivity after firing test is larger than 10^4S/cm. In this study, room temperature through the whole process and low pressure during the transferring will keep a low cost.

We present a replication process, named reversal soft ultraviolet (UV) nanoimprint, to fabricate a high-aspect-ratio flexible subwavelength grating (SWG) on a polyurethane acrylate (PUA). This nanopatterning technique consists of casting, reversal UV imprint, and dry release. The UV curing process of PUA to avoid pattern collapse is investigated. Revalpha film acts as the supporting and sacrificial layer during the whole process due to its special surface energy property. The free-standing PUA structures with a period of 200 nm and a depth of 350 nm can be automatically released from the Revalpha film by heating. The PUA resist is well suited to replicate fine patterns of the mold with high aspect ratio and large area precisely and uniformly for low surface energy and low viscosity. The measured transmittance is compared with the calculation results based on rigorous coupled-wave analysis in the wavelength region ranging from 500 to 800 nm. The experimental results agree well with the theoretical calculations.

Polymer-based micro/nano fluidic devices are becoming increasingly important for biological applications and fluidic control. In this paper, we propose a new method for the enclosure of the large-area channel by thermal bonding at low pressure using a flexible PET film material as bonding substrate. The flexible film allows bonding of micro/nano pattern features at such a low pressure primarily due to ''sequential'' bonding made possible by the mold flexibility and the conformal contact made between the bonding layer and the structure layer in large area. According to the bonding mechanism investigated using VOF simulation and experiments, high bonding temperature makes melt bonding polymer be filled into the trenches inevitably and achieve the chain entanglement of the polymer over the boundary by the capillary force. This fabrication technique has great potential for low-cost mass production of polymeric-based micro/nano fluidic devices.

It is still very difficult for researchers and engineers to implement the simulation analysis including a complete process and a full model with the complicated arch dam and the foundation, and to evaluate the cracking potential in the construction and service periods. To take Xiaowan project of China for an example, a practical system of simulation feedback analysis, a specific cracking criterion, and a resolution for the conflicting requirements of temperature and stress/strain simulation are presented, which are put into a successful practice. The simulation results of temperature, stress, and cracking are identical well with the monitor data. A modified temperature control measure is propounded, and the significant effect is gained by adopting the new scheme.

This paper mainly studies the mechanical properties of hollow block made from shale, coal gangue and sawdust. In China, shale is gradually used as substitute material for clay in the manufacture of sintered masonry materials. The research goal was to provide basis for the generalization and application of the fired shale hollow block through uniaxial compress compression test and failure mode under biaxial stress state. Results showed that the hollow block had reliable compressive strength and bond strength with lower density and good thermal insulation performance, meaning the feasibility of application in practical engineering.