工业大麻秆的显微构造和纤维形态研究

大麻秆芯是大麻的废弃物,一种优质的木质纤维原料。为了更好地开发和利用这种原料,论文主要对大麻秆的显微构造和纤维形态进行了研究,结果表明大麻秆的显微构造类似于阔叶材的散孔材。大麻秆皮部的纤维平均长度为22.7 mm,平均壁腔比为0.40,平均长宽比为705.38,83.5%纤维的长度为11～30 mm,72%的细胞长宽比为310～900,72%的壁腔比为0.11～0.50;是一种长度大、壁腔比小、长宽比大的优质纤维原料。而木质部的纤维平均长度为0.65 mm,平均壁腔比为0.32,平均长宽比为29.53,92%纤维的长度为0.41～0.90 mm,91.5%纤维的长宽比为11～50,66%纤维的壁腔比为0.11～0.40;是一种长度中等,长宽比大,壁腔比小的优质原料,可用于造纸和人造板制造的工业原料。     

连续聚酯装置增容

叙述该装置增容的各项措施。在充分利用原有厂房、设备的基础上 ,经过物料衡算 ,调整部分设备和部件解决物流瓶颈 ;更换终聚釜气相出口挡板 ,由圆形换成扇形 ,并尽量缩短与出口的距离以防止真空系统堵塞。浆料总量比保持在 1.74,酯化温度提高 2～ 3℃ ,压力增加 5～ 8kPa,停留时间不变或略有缩小 ;预缩聚Ⅱ的液位加大到 45 % ,升高温度 ,余压降低到1.3kPa ,搅拌转速调为 8.9r/min ;终缩聚液位增加到 49% ,并适当提高搅拌速度等。当熔体日产量由 32 5t提到 35 3t时 ,切片质量指标没有明显变化 ,一等品率在 99%以上。     

Permeability model for a woven fabric

The resin transfer molding (RTM) method is used to manufacture composite parts. The reinforcing fibers are placed in a mold cavity and the resin is injected to fill up the empty spaces. After the resin cures, the mold is opened and the part ejected. To predict necessary pressures and filling times and the proper locations for the inlet ports for resin injection and vents for air ejection it is necessary to model the resin infiltration process. A key to this modeling is permeability which characterizes the resistance of fibers to the flow of infiltrating resin. A simplified model for in-plane permeability of fabric reinforcement (preform) is developed here. This model uses lubrication theory for modeling the flow through open pores and Darcy's law for the transverse flow through the reinforcement. Scaling analysis is provided to justify the simplification and to estimate the range of validity for resulting expressions. Extension of the model to cover multi-layered preforms is derived. Boundary conditions and the data necessary to specify the problem geometry are discussed. A numerical experiment is conducted to estimate the influence of the transverse permeability of the preform on the solution. A calculation is provided for the permeability of a plain weave fabric.     

粗糙集与模糊推理相集成的过程建模方法及其应用

针对复杂化工过程机理建模困难的问题,采用适应性较广的模糊方法经验建模,鉴于模糊法对于高维、强相关的样本数据很难导出规则,本文提出先用粗糙集方法消除冗余性,约简系统,获取最小规则集,在此基础上构建结构合理、参数可适当初始化的模糊-神经网络,并采用LM算法训练,收敛速率快,模型预测性能良好.将此法用于PTA装置溶剂脱水塔精馏过程的经验建模,效果令人满意,性能优于现代统计方法和前馈神经网络.     

Approximate solutions for the ignition of a solid as a function of the Biot number

The ignition of a finite planar 1‐dimensional solid is addressed for constant applied radiant heat flux. An ignition temperature criterion is used, with constant properties, and linearized reradiation. An approximate integral analysis leads to analytic formulas to predict the ignition time in terms of Biot (Bi) number and heat flux. The accuracy of the integral solution is found to be good compared to the exact infinite series solution for the conduction equation. The integral model is then used to assess the accuracy of common ideal thick and thin formulas for ignition. There is a domain of heat flux and Bi where the ideal formulas are not accurate. An example is given where the integral model is accurately applied to ignition data to illustrate the range where the ideal formula is not accurate.     

Design of flyash concrete

A method for the design of flyash concrete to achieve a specified compressive strength at 7 and 28 days is presented. The method is simple and easy to use. The validity of this method has been tested by comparing the actual and the predicted strength for a number of mixes.Abrams' law is used in this method to develop design charts; the law is found to hold good for flyash concrete when the water cement ratio is replaced by the water cementitious ratio. The constants of the equations are found to vary according to a cubic polynomial of the flyash cement ratio. The reduction in the water demand with the increase in the flyash cement ratio is also included. It is shown that the contribution to the compressive strength due to the pozzolanic reaction is related to both the curing period and the flyash cement ratio. The paper also includes a typical design example.     

Universal sequential outlier hypothesis testing

Universal outlier hypothesis testing is studied in a sequential setting. Multiple observation sequences are collected, a small subset of which are outliers. A sequence is considered an outlier if the observations in that sequence are generated by an “outlier” distribution, distinct from a common “typical” distribution governing the majority of the sequences. Apart from being distinct, the outlier and typical distributions can be arbitrarily close. The goal is to design a universal test to best discern all the outlier sequences. A universal test with the flavor of the repeated significance test is proposed and its asymptotic performance, as the error probability goes to zero, is characterized under various universal settings. The proposed test is shown to be universally consistent. For the model with at most one outlier, conditioned on the outlier being present, the test is shown to be asymptotically optimal universally when the typical distribution is known and as the number of sequences goes to infinity when neither the outlier nor the typical distribution is known. With multiple identical outliers, the test is shown to be asymptotically optimal universally when the number of outliers is the largest possible and with the typical distribution being known, and its asymptotic performance with neither the outlier nor the typical distribution being known is also characterized. Extensions of the findings to models with multiple distinct outliers are also discussed. In all cases, it is shown that the asymptotic performance guarantees for the proposed test when neither the outlier nor the typical distribution is known converge to those when the typical distribution is known as the number of sequences goes to infinity.     

Adhesion of RFL-coated aramid fibres to elastomers: The role of elastomer–latex compatibility

The performance of fibre-reinforced composites is strongly dependent on the nature and the strength of the fibre–matrix interface. Good interfacial bonding is required to ensure load transfer from matrix to reinforcing fibres. For rubber-reinforced composites, resorcinol formaldehyde latex (RFL) is known as a fibre surface coating which is able to provide good adhesion between rubber and fibres. In the present study, aramid fibres are investigated, because of their significantly higher modulus and strength, compared to other commercial fibres. Their adhesion after being coated with RFL, in compounds based on natural rubber (NR) and in NR blended with a small amount of styrene butadiene rubber (SBR) is investigated. It is shown that though having very similar tensile properties, the latter compound has much better adhesion to RFL which is also less sensitive to RFL ageing, compared to the pure NR compound. It is argued that an interphase region is formed between RFL and the elastomer, which is stronger for the compound containing SBR due to its enhanced compatibility with the latex part of the RFL.     

LIFE CYCLE ASSESSMENT OF AN ENERGY-SYSTEM WITH A SUPERHEATED STEAM DRYER INTEGRATED IN A LOCAL DISTRICT HEAT AND POWER PLANT.

Life cycle assessment (LCA) is a method for analysing and assessing the environmental impact of a material, product or service throughout the entire life cycle. In this study 100 GWh heat is to be demanded by a local heat district. A mixture of coal and wet biofuel is frequently used as fuel for steam generation (Case 1). A conversion of the mixed fuel to dried biofuel is proposed. In the district it is also estimated that it is possible for 4000 private houses to convert from oil to wood pellets. It is proposed that a sustainable solution to the actual problem is to combine heat and power production together with an in improvement in the quality of wood residues and manufacture of pellets. It is also proposed that a steam dryer is integrated to the system (Case 2).

Most of the heat from the drying process is used to the municipal heating networks. In this study the environmental impact of the two cases is examined with LCA. Different valuation methods shows that Case 2 is an improvement over Case 1, but there is diversity in the magnitudes of environmental impact in the comparison of the cases. The differences depend particularly on how the emissions of CO₂, NO_x and hydrocarbons are estimated. The impact of the organic compounds from the exhaust gas during the drying is estimated as low in all of the three used methods.     

重新认识磷矿加工的科学合理性 实施循环经济可持续发展战略

介绍了磷对生命及磷化工行业的重要性,分析了目前高浓度磷肥产能过剩的现状及带来的困境和隐患。指出每年增加的磷石膏利用率,不可能从根本上解决潜在的环境与资源危机。呼吁调整国内当前的磷肥结构和改变传统的施肥观念,应减少发展有磷石膏排出的产品数量,重新认识钙镁磷肥。     

Microcomputer-based system for data acquisition and analysis of oxygen uptake studies

The use of a Warburg Respirometer to study oxidation reactions is tedious and time-consuming. A microcomputer-based oxygen uptake device that is more sensitive than a Warburg Respirometer is described. The device consists of stainless steel or Teflon reaction vessels coupled to ultrasensitive pressure transducers. A high speed analog to digital convertor is used to poll the transducers. The direct memory access (DMA) controller of an IBM XT is used to poll the convertor and store the data in memory. Software used to program the DMA controller and IBM XT is described. The reproducibility and utility of the device is demonstrated with a brief study of lipid oxidation.     

CFRP层板的疲劳损伤研究方法

介绍了CFRP层板疲劳损伤研究方面的主要模型。剩余强度来度量疲劳损伤破坏准则清楚明了，但实验工作量大、费用高，并且一个试件只能得到一个数据；剩余刚度可在疲劳试验过程中连续测量而不影响材料的性能，但破坏准则较难确定，弹性模量对损伤不很敏感；用电阻的变化来反映碳纤维层板结构的疲劳损伤操作简单易行，具有较高的工程实用价值。     

Solubility of Natural Gas in Diesel Fuel

The solubility of commercially available natural gas in commercially available diesel fuel at room temperature and defined pressure is investigated experimentally. The gas phase is considered to be pure methane. The use of Henry's law to model the solubility is discussed. Solubility is given in terms of the mole fraction and the volumetric mass concentration of dissolved gas and the corresponding Henry's coefficients. The solubility is compared to that of pure methane in pure hexadecane, which is similar to diesel fuel with respect to the mean carbon number.     

Diffusion Deposition on a Cylinder Due to Nearly Parallel Flow

The diffusional deposition of the particles in an aerosol on a cylindrical fiber when the aerosol is carried in a slow laminar flow whose mean direction is at an angle to the axis of the fiber is studied by considering the parallel and transverse components of this flow, ft is shown that when the flow is nearly transverse to the fiber, the analysis carried out by Natanson and Stechkina applies. When the flow is nearly parallel to the fiber, the asymptotic method of Stechkina is used to obtain an expression for the contribution to the single fiber diffusion efficiency. This contribution is shown to be somewhat less, but of the same order of magnitude, as that obtained by Natanson and Stechkina for purely transverse flow.     

内电解法处理印染废水的效果研究与分析

印染废水成分复杂、色度高、CODCr高且难降解,对环境造成较大污染。印染废水处理一般采用生化一混凝沉淀法、混凝气浮法、化学氧化及活性炭吸附法等,但这些方法存在运行费用较高、不易管理等缺点。内电解的基本原理是利用铁屑中的铁和炭组分构成微小原电池的正极和负极,以充入的废水为电解质溶液,发生氧化-还原反应,形成原电池。利用内电解对印染废水进行预处理,脱色率可达75％。90％,CODCr去除率达55％左右。另外还可提高废水的可生化性,废水的BOD5/CODCr值从原来的0.23提高到0．57,为后续生化处理和处理后达标排放奠定了基础,且运行成本低,易于管理。     

Considerations on nonlinear model predictive control techniques

The nonlinear model predictive control (NMPC) is an on-line application based on nonlinear convolution models. It is an appealing control methodology, but it is difficult to implement and its solution is not so performing since it unavoidably means to solve a usually large-scale, constrained, and multidimensional optimization. To increase the difficulty, this optimization problem is subject to computationally heavy differential and algebraic constraints constituting the same convolution model and the least squares nature of the objective function easily leads to narrow valleys and multimodality issues.Beyond a short review of the state-of-the-art, the paper is aimed at highlighting the possibility to exploit at best the intrinsic features of the specific system one is going to control using the NMPC. The idea is to give the NMPC the possibility to automatically select the best combination of algorithms (differential solvers and optimizers) in accordance with the specific problem to be solved. From this perspective, the NMPC could be easily extended to many scientific fields traditionally far from process systems and computer-aided process engineering and the user has not to worry about which specific differential solvers and optimizers are needed to solve his/her problem.     

The coefficient of restitution for normal incident, low velocity particle impacts

This paper examines the theoretical regimes underlying the collision and recoil of elasto-plastic particles in low-velocity normal impacts. The coefficient of restitution is shown to be an approximate function of the ratio of the relative impact velocity to the system compressional wave speed, and the ratio of yield pressure to Young's modulus. The system compressional wave speed is further a function of the relative radii of the impacting particles, and it is predicted that the coefficient of restitution for equally sized sphere-sphere impacts is about 19% small than for sphere-plate impacts of otherwise identical particles. This result is confirmed experimentally. Theory is also developed to quantify an increase in restitution coefficient following identical impacts at the same point. Progressive plastic deformation about the impact point leads to a collision that is increasingly more elastic, and the restitution coefficient for typical particles approaches unity after about five to 10 impacts. This is also approximately confirmed experimentally.     

Volume of fluid method for interfacial reactive mass transfer: Application to stable liquid film

A volume of fluid method is developed in order to simulate reactive mass transfer in two-phase flows and is applied to study reactive laminar liquid film. The thermodynamic equilibrium of chemical species at the interface is considered using Henry's law. The chemical species concentration equation is solved using primitive variables and local fluxes are locally directly calculated at the interface. The present treatment of jump discontinuity of chemical concentration is consistent with a volume of fluid approach and the difficulty to calculate accurate local mass flux across interface is overcome. For plane interface, the precision of the numerical simulation is found to be very satisfactory while for curved interface a special procedure has been developed to reduce the development of spurious fluxes at the interface. The algorithm is validated for different cases by comparison with available solutions. The method is then applied to study non-reactive and reactive mass transfer in a falling liquid film. The results show that the liquid side mass transfer is well predicted by the Higbie (1935) theory when the transfer is controlled by the film advection provided that adequate parameters are considered, i.e. the actual velocity at interface and not the average liquid film velocity. For situations controlled by diffusion, the Sherwood number tends to a constant value characteristic of purely diffusive situations. For the reactive mass transfer, first and second order irreversible chemical reactions in the liquid phase are considered. The numerical results are compared respectively, with Danckwerts (1970) and Brian et al. (1961) solutions and good agreement is observed. The proposed Volume of Fluid method is shown to be well adapted to deal with interfacial reactive mass transfer problems.     

人工湿地填料对氮磷的静态吸附筛选实验

通过考察填料对水中氮磷的吸附性能,为人工湿地填料的选择提供依据。在水中投加一定量填料,在不同条件下进行磁力搅拌,测定填料对氮磷的吸附性能。结果表明填料粒径为8~12目,固液比50 mg/L,搅拌速率300 r/min,搅拌时间3 h,原水pH约为6.5,氨氮的初始质量浓度30 mg/L左右、磷的初始质量浓度3 mg/L左右时,煤灰渣对氨氮的去除率6.6%,对磷的去除率30%;沸石对氨氮的去除率40%,对磷的去除率22.8%;蛭石对氨氮的去除率28.5%,对磷的去除率9%。pH对氮磷吸附的影响较大,原水在碱性和中性的条件下,对氮磷的吸附性能要优于酸性条件。     

Distributed semi-cooperative filter for a nonlinear multi-agent system with heterogeneous and homologous unknown inputs

In this study, the simultaneous estimation of the states and unknown inputs for a nonlinear multi-agent system with homologous and heterogeneous unknown inputs is performed. The decentralized sub-filter is used to estimate the states and heterogeneous unknown inputs, whereas the distributed sub-filter is used to estimate the homologous unknown inputs. The extended Kalman filter is used to solve the estimation problem for nonlinear systems. Compared with previous studies, the distributed solution is improved to relax the existence of the homologous unknown input sub-filter. Moreover, the updating method of the residual generator is improved to relax the heterogeneous unknown input sub-filter. The practical problem of estimating the state of charge and temperature of the battery pack is used to verify the effectiveness of the proposed filter.