软测量的工程化设计

将软测量应用到工业生产之前必须解决其工程化设计的问题.为此,在软测量技术理论研究和应用经验的基础上,对软测量工程化设计中应解决的关键问题和解决方法进行了研究.软测量的工程化设计包括机理分析、辅助变量选择、数据采集和预处理、建立软测量模型、设计校正模块等步骤.其关键技术在于软测量过程的数据处理、模型的建立和校正.并以杭州龙山化工厂碳酸化塔中C02浓度软测量的工程化设计为例,对工程化设计中的一些关键问题处理进行介绍.实践表明,软测量的工程化设计在实际工业生产中具有很好的应用性和指导性,但也有待更进一步的研究.     

Surface engineered active photocatalysts without noble metals: CuS–ZnxCd1−xS nanospheres by one-step synthesis

CuS(y)–Zn_xCd_1−xS (where 0.3 ≤ x ≤ 0.8, 0% ≤ y ≤ 15.8%) nanospheres with a Zn and Cu-rich surface were synthesized via a one-step method in ethylene glycol. Structural, morphological and optical properties of the samples have been investigated by XRD, TEM, XPS, ICP, N₂ physisorption and UV–vis DRS techniques. The cubic phased nanospheres of approximately 20–30 nm in diameter are comprised of nanocrystals of about 5 nm. Due to the reactivity difference among the metal ions in the organic solvent, the surface of the nanospheres was found enriched with Zn and Cu sulfide layers. In the absence of Cu, sample Zn_0.65Cd_0.35S gives a H₂ production rate of 29 μmol/h under the irradiation of a 300 W Xenon lamp with a cut-off filter (λ ≥ 420 nm) in aqueous solutions containing S²⁻ and SO₃²⁻. The activity, which can only be increased by four times by a traditional Pt cocatalyst for the as-prepared Zn_0.65Cd_0.35S sample, can be enhanced by around 20 times to 550 μmol/h and 624 μmol/h after adding 5.9 mol% and 11.1 mol% (metal basis) of Cu during the synthesis to form a Cu-rich surface. It is believed that the surface Cu²⁺ 3d impurity levels can function as the same role of the noble metal cocatalysts as charge accommodation sites for the charge separation, and hence increase the photocatalytic performance for water splitting.     

High efficiency process for the production of pure oxygen based on solid oxide fuel cell–solid oxide electrolyzer technology

This paper presents a novel system for production of pure oxygen based on the integration of a solid oxide fuel cell (SOFC) and a solid oxide electrolyzer (SOEC). In the proposed arrangement, the SOFC provides electricity, heat and H₂O in vapour phase to the SOEC which carries out the inverse reactions of the SOFC, that is the separation of H₂O into H₂ (used as a fuel for the SOFC) and O₂ (representing the yield of the system). Simulations carried out in different operating conditions show that when the integrated SOFC–SOEC device runs at low current densities (less than 1000 A m⁻²), pure oxygen can be generated with an electric consumption comparable to mid-size cryogenic air separation units, and significantly lower than small scale systems based on the PSA technology.     

Estimating using cost significant global cost models

Cost significant models have been suggested as one way of overcoming criticisms of the amount of detail contained within the traditional bill of quantities. Recent research into these models reveals a lack of formal rules for the selection of work packages to be used within the models, and a potential to overestimate the cost of projects. This paper presents a methodology for selecting work packages, and recommends a refinement to the technique that reduces the variability in estimates produced using cost significance. Estimates are produced using both the traditional method of producing cost significant models, and a refined global cost methodology. Both techniques are tested against unpriced bills to measure the difference in results, with significant improvements being achieved with the new technique.     

Determination of Viscoelastic Poisson’s Ratio of Solid Propellants using an Accuracy‐enhanced 2D Digital Image Correlation Technique

Poisson’s ratio plays a significant role in the structural response of solid propellants, which is, in essence, a nearly incompressible viscoelastic material. Numerical models that assume a constant Poisson’s ratio generally cannot achieve good results, thus requiring an accurate knowledge of time‐dependent viscoelastic Poisson’s ratio of solid propellants. In this work, accurate determination of tensile strains and viscoelastic Poisson’s ratio of solid propellants using an accuracy‐enhanced 2D digital image correlation (DIC) technique is described. To achieve high‐accuracy measurement, great improvements were made to regular 2D‐DIC technique to maximally eliminate the errors caused by non‐ideal loading conditions, specimen deformation and lens distortion. Rigid body translation tests with zero strain state are first performed to verify the accuracy of the proposed DIC technique. Then application of the proposed technique for determining the time‐varying viscoelastic Poisson’s ratios of solid propellants in stress relaxation tests are demonstrated. The results reveal that, by adequately eliminating the measurement errors associated with the unavoidable out‐of‐plane displacements and lens distortion, the present DIC technique can be used for precise determination of viscoelastic Poisson’s ratio of solid propellants, which is found to be increasing nonlinearly to the incompressible value of 0.50 as time increases.     

Analysis of Leakages in a Solid Oxide Fuel Cell Stack in a System Environment

A solid oxide fuel cell (SOFC) stack can exhibit both anodic and cathodic leakages, i.e. a fuel leak from the anode side and an air leak from the cathode side of the stack, respectively. This study describes the results of an in‐situ leakage analysis conducted for a planar SOFC stack during 2000 hours of operation in an actual system environment. The leakages are quantified experimentally at nominal system operating conditions by conducting composition analysis and flow metering of gases for both fuel and air subsystems. Based on the calculated atomic hydrogen‐to‐carbon ratio of the fuel and air gases, it is found that the fuel leakages are mostly selective by nature: the leaking fuel gas does not have the same composition as the fuel system gas. A simple diffusive leakage model, based on the leakage being driven by concentration differences weighted by diffusion coefficients, is applied to quantify the amount of leakages. The leakage model provides a good correspondence with the experimental results of the gas analysis.     

Shape transformation by boundary representation interpolation: A recursive approach to establishing face correspondences

The issues relating to the shape transformation problem are discussed and a new algorithm is presented for computing the transformation of one shape into another. In this algorithm, the boundary definitions of the two initial shapes are used and a mapping is established between the vertices and edges of the respective objects. New vertices and edges are introduced into the object definitions when necessary to establish a one-to-one vertex correspondence and to match connectivity relationships between vertices. These can then be used to do a vertex-to-vertex interpolation that maintains valid polyhedral topologies for all of the intermediate shapes. The algorithm establishes a mapping between areas of the object such that adjacency relationships are preserved. These areas are recursively subdivided so that adjacency relationships of subareas are also preserved. During subdivision, vertices and edges are added to the boundaries of subareas so that a one-to-one mapping is established between them. Subdivision continues until each subarea consists of a single face. The algorithm presented works for objects that are topologically equivalent to spheres and can easily be extended to other pairs of objects as long as they are topologically equivalent to each other.     

The visualization of knots and braids

We describe a new method for modelling braids and certain classes of knots and links, and how they may be visualized. The method uses generalized cylinders built around a bicubic spline centre line. We also show how multi-stranded, recursive, hawser laid ropes can be modelled using related techniques.     

Microorganisms in landfill bioreactors for accelerated stabilization of solid wastes

Landfill bioreactors (LBRs) with management of leachate and biogas have presented numerous advantages such as accelerated stabilization of solid wastes, reduced amount of leachate, and in situ leachate treatment. Such advantages have minimized environmental risks, have allowed extension of the useful life of the landfill site, and have fostered cost reduction. LBRs of three types have been developed using both anaerobic and aerobic modes: anaerobic, aerobic, and hybrid. Microorganisms in landfills cause various reactions related with organic fractions and heavy metals. Such functions have been stimulated in LBRs by recirculation of leachate with or without aeration. To date, most studies of microorganisms in LBRs have analyzed bacteria and archaea based on 16S rRNA genes and have analyzed fungi based on 18S rRNA genes from a taxonomical viewpoint. Indicator genes for specific functions in LBRs such as nitrification, denitrification, and methane production have also been monitored. The population dynamics of microorganisms in LBRs have been partially clarified, but the obtained data remain limited because of highly heterogeneous features of solid wastes inside LBRs. Systematic monitoring of microorganisms should be established to improve LBR performance.     

沉淀剂的不同对固体超强酸SO_4~(2-)/TiO_2-NiO性能的影响

通过对固体超强酸的比表面测定,差热分析及催化酯化性能考察, 研究了不同沉淀剂对固体超强酸ＳＯ４２－ ／ＴｉＯ２ － ＮｉＯ 催化剂在物性和催化性能的影响,认为尿素作沉淀剂可增强ＴｉＯ２ 与ＮｉＯ之间相互作用,抑制Ｎｉ 离子和ＳＯ４２ － 生成盐,氨水作为沉淀剂则不能促使ＴｉＯ２ 与ＮｉＯ 的强相互作用,用尿素作沉淀剂得到的催化剂比表面、稳定性要比氨水作沉淀剂时的比表面大,稳定性要高。