水性电化铝离型层涂料的制备与研究

本文采用水性丙烯酸改进聚氨酯、水性附着力促进剂、乙醇、去离子水、消泡剂、分散剂、流平剂等制备一种水性电化铝离型层涂料,并选择三种类型的水性附着力促进剂研究附着力促进剂对电化铝离型层的性能影响。结果表明,附着力促进剂可以提高电化铝离型层的离型力和切割性。有机金属类附着力促进剂更适合水性离型层体系,随着促进剂用量的增加,离型层的的离型力逐渐增加,切割性从有残留到转移不全过渡。促进剂质量分数为2.0%时,离型层的综合性能优异。

硅系合成革离型纸的研究

优选出耐热性较好的3种丙烯酸类乳液作为底涂主剂,水性有机硅树脂作为离型剂,并通过混合正交实验探讨了离型层配比、底涂主剂、底涂压光压力及离型层涂布量对离型纸首次剥离强度和可重复使用次数的影响大小,由此确定了达到最佳离型性能,即首次剥离强度为8.7×10-2 kN/m,可重复使用次数为35次的相应涂层工艺条件是:底涂主剂采用的丙烯酸类乳液,其Tg为6℃、涂4-杯黏度20 s时原液固含量为45.0%、原液黏度为300 mPa.s。底涂压光压力为8 MPa,离型层涂布量为1～2 g/m2,离型层配比为4∶1,在该工艺条件下自制硅系合成革离型纸,其耐溶剂性与进口纸相当或更优。

济南大易造纸有限公司——研制开发出新产品——离型纸

济南大易造纸有限公司根据市场需求变化,近期成功的研制开发出了一种新型纸——离型纸。这种纸可分为硅系列离型纸和非硅系列离型纸,是主要用于生产聚氨酯(PU)和聚氯乙烯(PVC)人造革的工业用纸。离型纸生产人造革是在离型层表面涂布粗状树脂,经发泡工艺处理、烘干、交联、固化定型。

热转印膜研究进展

文章以印刷技术的发展为背景,介绍了热转印膜的结构特点和制作工艺,着重叙述热转印膜各部分结构层的功能与内在联系,以及在热转印应用过程中对转印膜的所要达到的性能要求,最后对其研究进展进行了总结性说明。

可降解胶带的研究进展

随着人们环保意识的增加,为实现包装的绿色发展,减少白色污染,包装产品的可降解性能研究有着重要的意义。本文根据胶带的结构特点,分别从离型层、基材层和胶粘层三个方面分别对胶带的可降解性能进行全面的分析,阐述了可降解胶带研究进展。

Influences of pre-existing fracture on ground deformation induced by normal faulting in mixed ground conditions

Physical model tests have been conducted by various researchers to investigate fault rupture propagation and ground deformation induced by bedrock faulting. However, the effects of pre-existing fracture on ground deformation are not fully understood. In this work, six centrifuge tests are reported to investigate the influence of pre-existing fracture on ground deformation induced by normal faulting in sand, clay and nine-layered soil with interbedded sand and clay layers. Shear box tests were conducted to develop a filter paper technique, which was adopted in soil model preparation to simulate the effects of pre-existing fracture in centrifuge tests. Centrifuge test results show that ground deformation mechanism in clay, sand and nine-layered soil strata is classified as a stationary zone, a shearing zone and a rigid body zone. Inclination of the strain localization is governed by the dilatancy of soil material. Moreover, the pre-existing fracture provides a preferential path for ground deformation and results in a scarp at the ground surface in sand. On the contrary, fault ruptures are observed at the ground surface in clay and nine-layered soil strata.

Prediction of upper limit position of bedding separation overlying a coal roadway within an extra-thick coal seam

Failure of the surrounding rock around a roadway induced by roof separation is one major type of underground roof-fall accidents.This failure can especially be commonly-seen in a bottom-driven roadway within an extra-thick coal seam("bottom-driven roadway"is used throughout for ease of reference),containing weak partings in their roof coal seams.To determine the upper limit position of the roof interlayer separation is the primary premise for roof control.In this study,a mechanical model for predicting the interlayer separation overlying a bottom-driven roadway within an extra-thick coal seam was established and used to deduce the vertical stress,and length,of the elastic,and plastic zones in the rock strata above the wall of the roadway as well as the formulae for calculating the deflection in different regions of rock strata under bearing stress.Also,an approach was proposed,calculating the stratum load,deflection,and limiting span of the upper limit position of the interlayer separation in a thick coal seam.Based on the key strata control theory and its influence of bedding separation,a set of methods judging the upper limit position of the roof interlayer separation were constructed.In addition,the theoretical prediction and field monitoring for the upper limit position of interlayer separation were conducted in a typical roadway.The results obtained by these two methods are consistent,indicating that the methods proposed are conducive to improving roof control in a thick coal seam.

AN ADVANCED DUAL-FREQUENCY POSITIONING ALGORITHM FOR SATELLITE NAVIGATION RECEIVERS

With the development of the Ground Positioning System (GPS) modernization and the expectable implementation of Galileo, people pay more and more attention to civil applications on multi-frequency signals. This paper proposes a new and advanced positioning algorithm for the dual-frequency satellite navigation receivers, concerning the various influences of all the ranging error sources and taking advantage of the Klobuchar single-frequency ionospheric model. The paper also presents positioning precision provided by the new algorithm. Theoretical analysis and experimental results show that, the new dual-frequency positioning algorithm can achieve higher positioning accu- racy than the single-frequency positioning algorithm and the traditional dual-frequency positioning algorithm.

Metal cation exchanged silica gel for identification of cationic and nonionic surfactants with preliminary separation by thin layer chromatography

Silica gel impregnated with 1% aqueous solutions of different metal cations （Li^＋, Mg^2＋, Zn^2＋, Cu^2＋, Co^2＋, Ni^2＋, Ba^2＋and Th^4＋） has been used for the analysis of nonionic and cationic surfaetants using simple aqueous acetone as mobile phase system. Co^2＋ was found the most suitable impregnant for the mutual separation of nonionic surfactants （Brij-35 and Brij-57） and cationic from nonionic surfactants （tetmdecyltrimethylammonium bromide and Cween-20）. Zinc sulphate impregnation （Zn^2＋-silica gel） shows identical chromatographic behavior and these layers are useful to separate nonionic surfactant （Brij-35） from cationic surfaetant （cetylpyridinium chloride）. The mutual separation of B J-35 and B J-57 is not influenced by the presence of optical brightener in the sample.

A Multi-Level Authorization Based Tenant Separation Mechanism in Cloud Computing Environment

Separation issue is one of the most important problems about cloud computing security. Tenants should be separated from each other based on cloud infrastructure and different users from one tenant should be separated from each other with the constraint of security policies. Learning from the notion of trusted cloud computing and trustworthiness in cloud, in this paper, a multi-level authorization separation model is formally described, and a series of rules are proposed to summarize the separation property of this model. The correctness of the rules is proved. Furthermore, based on this model, a tenant separation mechanism is deployed in a real world mixed-critical information system. Performance benchmarks have shown the availability and efficiency of this mechanism.

New understanding achieved from 2 years of Chinese ionospheric investigations

In the mainland of China, the number of ionospheric research groups is more than 10. Around 110 articles related to ionospheric physics have been published during 2014–2015. In this annual national report of the Committee on Space Research(COSPAR), we will outline some recent progresses in ionospheric studies conducted by the Chinese mainland scientists in the past 2 years. These investigations cover(1) the ionosphere responses to geomagnetic activities;(2) ionospheric climatology and structures;(3) couplings between the ionosphere, plasmasphere and lower atmosphere, and possible seismic signatures in the ionosphere;(4) ionospheric irregularities and scintillation;(5) ionospheric models, data assimilation and simulations;(6) ionospheric dynamics and electrodynamics;(7) progresses in the observation methodology and technique; and(8) planetary ionospheres. Such investigations will strengthen our ability to monitor the ionosphere,provide a better understanding of the ionospheric states and the underlying fundamental processes, and improve the ionospheric modeling, forecasting, and related applications.

The variation of the estimated GPS instrumental bias and its possible connection with ionospheric variability

Based on the analysis of the satellite DCB data estimated by our method and the Center for Orbit Determination in Europe(CODE)from 1999 to 2011,the features of the temporal variation of differential code biases(DCB)are studied.Summarily,there are three types of variations in DCB on different time scales.The first one is the day-to-day variation that exhibits more obviously in solar maximum years.The second one is the variation with about one year periodic variation that behaves more obviously from 1999 to 2004.The last one is the monotonously descending tendency from 1999 to 2010.Considering the basic ionospheric approximation in DCB estimation method,the features of the variability of the ionospheric morphology from 1999to 2010 are also displayed based on the ionospheric characteristic parameters.It can be concluded that the day-to-day and annual variation of the estimated global positioning system(GPS).DCB is related to the ionospheric variability.The variation of DCBs on solar cycle time scale includes the real hardware DCBs and pseudo-DCBs induced by ionospheric variation.No doubt,these kinds of"pseudo"variations of DCB will affect the precision of ionospheric total electron content(TEC)derived from the GPS data.In addition,this study is helpful for evaluating the influence of ionospheric weather on TEC derivation and is also useful for developing one estimation method of DCB with more stability and precision through introducing a more practical ionospheric model.

Improved method to derive equivalent current systems from global MHD simulations

Derivation of equivalent current systems(ECS)from a global magnetospheric magnetohydrodynamics(MHD)model is very useful in studying magnetosphere-ionosphere coupling,ground induction effects,and space weather forecast.In this study we introduce an improved method to derive the ECS from a global MHD model,which takes account of the obliqueness of the magnetic field lines.By comparing the ECS derived from this improved method and the previous method,we find that the main characteristics of the ECS derived from the two methods are generally consistent with each other,but the eastward-westward component of the geomagnetic perturbation calculated from the ECS derived from the improved method is much stronger than that from the previous method.We then compare the geomagnetic perturbation as a function of the interplanetary magnetic field(IMF)clock angle calculated from the ECS derived from both methods with the observations.The comparison indicates that the improved method can improve the performance of the simulation.Furthermore,it is found that the incomplete counterbalance of the geomagnetic effect produced by the ionospheric poloidal current and field-aligned current(FAC)contributes to most of the eastward-westward component of geomagnetic perturbation.

Global modeling 2^(nd)-order ionospheric delay and its effects on GNSS precise positioning

Ionospheric delay is one of the major error sources in GNSS navigation and positioning.Nowadays,the dual-frequency technique is the most widely used in ionospheric refraction correction.However,dual-frequency measurements can only eliminate the first-order term of ionospheric delay,while the effect of the second-order term on GNSS observations may be several centimeters.In this paper,two models,the International Reference Ionosphere (IRI) 2007 and International Geomagnetic Reference Field (IGRF) 11 are used to estimate the second-order term through the integral calculation method.Besides,the simplified single layer ionosphere model in a dipole moment approximation for the earth magnetic field is used.Since the traditional integral calculation method requires large calculation load and takes much time,it is not convenient for practical use.Additionally,although the simplified single layer ionosphere model is simple to implement,it results in larger errors.In this study,second-order term ionospheric correction formula proposed by Hoque (2007) is improved for estimating the second-order term at a global scale.Thus,it is more practicable to estimate the second-order term.More importantly,its results have a higher precision of the sub-millimeter level for a global scale in normal conditions.Compared with Hoque's original regional correction model,which calculates coefficients through polynomial fitting of elevation and latitudes,this study proposes a piece-wise look-up table and interpolation technique to modify Hoque model.Through utilizing a table file,the modified Hoque model can be conveniently implemented in an engineering software package,like as PANDA in this study.Through applying the proposed scheme for the second-order ionospheric correction into GNSS precise positioning in both PPP daily and epoch solutions,the results have shown south-shift characteristics in daily solution at a global scale and periodic change with VTEC daily variation in epoch positioning solution.

Tectonic contrast between the conjugate margins of the South China Sea and the implication for the differential extensional model

The extensional model of the South China Sea(SCS)has been widely studied,but remains under debate.Based on the latest high-quality multi-channel seismic data,bathymetric data,and other obtained seismic profiles,the asymmetric characteristics between the conjugate margins of the SCS are revealed and extensional model of the SCS margin is discussed further.Spatial variation of morphology,basement structure,and marginal faults are discovered among the SCS margin profiles.As for the NS-trending variation,the basement of northern margin displays in the shape of step downwards to the sea,while the basement of southern margin is composed of wide rotated and tilted blocks,without any obvious bathymetric change.The variation also exists in the development of marginal faults between the conjugate margins,and detachment fault system is identified on the southern margin.Along the southern margin from east to west,the Eastern and Southwestern Basins developed different structural units.Based on the tectonic contrast of the conjugate margins,differential extensional model is proposed to explain the spatial variation of the SCS structure,which introduces detachment faults controlling the evolution of the SCS.The upper crust above the detachment fault was deformed by simple shear,while the lower crust and upper mantle below the detachment fault was deformed by pure shear.Because of the different lateral transfer between the upper brittle faulting and the lower ductile extensional regions,there developed marginal plateau(Liyue basin)and outer rise(Zhenghe massif)on the lower plate margin of the Eastern Basin and the Southwestern Basin,respectively.The evolution of the present SCS may be influenced by the diachronous close of the paleo-SCS.

Establishment of N_mF_2 empirical model in the northern hemisphere based on COSMIC occultation data

Ionospheric peak value of F2 layer （NmF2） is an important parameter in the ionosphere, which has important applications in short-wave communication, ionospheric modeling and so on. In this paper, the empirical orthogonal function （EOF） decompo- sition method is used to analyze the NmFz obtained from the occultation data. Daily spatial distribution of NmF2 at the same time is relatively even. Variance of first modal is much larger than the other modals. A local wavelet power spectrum （LWPS） method is applied to analysis the cycle of Flo.7 index and time coefficient of first modal. The result shows that they have simi- lar cycle distribution, indicating that Flo.7 index is the main factor affecting variation of NmF〉 A function is established be- tween the tine coefficient of first modal and F10.7 index, average F10.7 index value of early 81 days fp by least squares method. The results show that contribution coefficient offp is negative which indicates that fp has an inert effect existing in the iono- sphere. Contribution coefficient of F10.7 is positive, which is consistent with the fact that it has an anomaly in winter/spring seasons. In summary, it is feasible to establish a mid-latitude empirical NmF2 model in northern hemisphere based on occulta- tion data and EOF decomposition method.

A new plasmapause location model based on THEMIS observations

A new empirical model of plasmapause location as functions of magnetic local time and geomagnetic indices has been developed based on the observations from THEMIS mission. We use the two-year data of electron density inferred from spacecraft potential to identify the plasmapause crossings and create a database of plasmapause locations. The database is further used to build up an empirical model of plasmapause related to magnetic local time based on the equation from O'Brien and Moldwin(2003). The new model is compared with previous plasmapause location models. It is found that our newly developed model is the best in predicting plasmapause locations among the existing models. The models based on Kp and Dst indices are better than the model based on AE index, suggesting that the plasmapause location is controlled by large scale convection of the magnetosphere.

BDS triple-frequency carrier-phase linear combination models and their characteristics

An investigation has been made on the models and characteristics of triple-frequency carrier-phase linear combinations for the Bei Dou Navigation Satellite System(BDS). Based on the three frequencies of the BDS, three categories of combinations are developed: ionosphere-free combinations(i.e., those that eliminate the ionospheric effect), minimum-noise combinations(those that mitigate the effects of thermal noise and multiple paths), and troposphere-free combinations(those that mitigate tropospheric effects). Both the ionosphere-free and troposphere-free combinations can be expressed as planes, whereas the minimum-noise combinations can be expressed as a line. The relationships between these three categories of linear combinations are investigated from the perspective of geometry. The angle between the troposphere-free plane and ionosphere-free plane is small, while the angles between the troposphere-free plane and the minimum-noise line, and between the ionosphere-free plane and the minimum-noise line, are large. Specifically, the troposphere-free plane is orthogonal to the minimum-noise line. By introducing the concepts of lane number and integer ionosphere number, the characteristics of the long-wavelength integer combinations and ionosphere-free integer combinations are investigated. The analysis indicates that the longest wavelength that can be formed for integer combinations is 146.53 m, and the ionosphere-free integer combinations all have large noise amplification factors. The ionosphere-free integer combination with minimum noise amplification factor is(0, 62, 59). According to the lane number, integer ionosphere number, and noise amplification factor, optimal integer combinations with different characteristics are presented. For general short baselines and long baselines, three independent integer combinations are suggested.

Preparation and performance evaluation of Er_2O_3 coating-type selective emitter

An Er203 coating-type selective emitter for themophotovoltaic application was prepared by plasma spray technology. The test results show that plasma spray technology could be used to prepare the Er203 coating-type selective emitter with good stability at 1400℃. Based on the measurements of the high temperature normal spectral emissivity and the spectral hemispherical emissivity of the samples at room temperature, the influence of the coating thickness was discussed, and the selective emission performance of the sample was evaluated using radiative efficiency as the criterion. The results demonstrate that the emission of substrate could not be neglected unless the coating thickness would be larger than the penetration depth, which is around 100 μm. The selective emission peak of the Er203 coating occurs at 1550 nm, matching well with the GaSb cells. However, the radiative efficiency is not larger than that of the SiC emitter, because the non-convertible emission of 1.725-5 μm accounts for a large proportion of the total radiation power, especially at high temperature. Effective suppression of this band emission is essential to the improvement of the radiation efficiency of the emitter.

Examples of Boundary Layers Associated with the Incompressible Navier-Stokes Equations

The author surveys a few examples of boundary layers for which the Prandtl boundary layer theory can be rigorously validated.All of them are associated with the incompressible Navier-Stokes equations for Newtonian fluids equipped with various Dirichlet boundary conditions(specified velocity).These examples include a family of(nonlinear 3D) plane parallel flows,a family of(nonlinear) parallel pipe flows,as well as flows with uniform injection and suction at the boundary.We also identify a key ingredient in establishing the validity of the Prandtl type theory,i.e.,a spectral constraint on the approximate solution to the Navier-Stokes system constructed by combining the inviscid solution and the solution to the Prandtl type system.This is an additional difficulty besides the wellknown issue related to the well-posedness of the Prandtl type system.It seems that the main obstruction to the verification of the spectral constraint condition is the possible separation of boundary layers.A common theme of these examples is the inhibition of separation of boundary layers either via suppressing the velocity normal to the boundary or by injection and suction at the boundary so that the spectral constraint can be verified.A meta theorem is then presented which covers all the cases considered here.