Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.

Manufacturing Process Selection of “Green” Oil Palm Natural Fiber Reinforced Polyurethane Composites Using Hybrid TEA Criteria Requirement and AHP Method for Automotive Crash Box

In this study,the best manufacturing process will be selected to build an automotive crash box using green oil palm natural fibre-reinforced polyurethane composite materials.This paper introduces an approach consist of technical aspects(T),the economic point of view(E)and availability(A),and it’s also called as TEA requirement.This approach was developed with the goal of assisting the design engineer in the selection of the best manufacturing process during the design phase at the criteria selection stage.In this study,the TEA requirement will integrate with the analytical hierarchy process(AHP)to assist decision makers or manufacturing engineers in determining the most appropriate manufacturing process to be employed in the manufacture of a composite automotive crash box(ACB)at the early stage of the product development process.It is obvious that a major challenge in the manufacturing selection process is lack of information regarding manufacturing of ACB using natural fibre composite(NFC).There have been no previous studies that examined ranking manufacturability processes in terms of their suitability.Therefore,the TEA-AHP hybrid method was introduced to provide unprejudiced criteria-ranking selection prior to evaluation of pairwise comparisons.At the end of this study,the pulforming process was selected as the best manufacturing process for fabrication of the ACB structural component.

DIFFERENCE SCHEME FOR TWO-PHASE FLOW

A numerical method for two-phase flow with hydrodynamics behavior was considered. The nonconservative hyperbolic governing equations proposed by Saurel and Gallout were adopted. Dissipative effects were neglected but they could be included in the model without major difficulties. Based on the opinion proposed by Abgrall that “a two phase system, uniform in velocity and pressure at t=0 will be uniform on the same variable during its temporal evolution", a simple accurate and fully Eulerian numerical method was presented for the simulation of multiphase compressible flows in hydrodynamic regime. The numerical method relies on Godunov-type scheme, with HLLC and Lax-Friedrichs type approximate Riemann solvers for the resolution of conservation equations, and nonconservative equation. Speed relaxation and pressure relaxation processes were introduced to account for the interaction between the phases. Test problem was presented in one space dimension which illustrated that our scheme is accurate, stable and oscillation free.

Study on an improved rotating microchannel separator in the intensification for demulsification and separation process

An improved rotating microchannel(IRM) separator was further explored in the intensification for demulsification and separation process. Oil-in-water(O/W) emulsion system of 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507)–water without emulsifier was employed to evaluate the performance of the new equipment. In this experiment, the influence on demulsification separation process was explored by changing the geometrical structure and channel height of the microchannel and combining the liquid–liquid two-phase flow pattern, and the correlation general graph between demulsification efficiency and dimensionless parameters was established. The total demulsification effect of the IRM and the separation capacity of the clear organic phase recovered from demulsification are significantly improved. In addition, the liquid–liquid two-phase flow pattern of the clear organic phase after demulsification and the remaining emulsion in the IRM are observed and recorded by high-speed photography. The separation ability of organic phase from the upper outlet can be significantly improved when the total demulsification rate of IRM is up to 90%. There are 3 types and 6 kinds of flow patterns observed. The results demonstrated that the suitable demulsification performance is obtained when the liquid–liquid two-phase inside the IRM is in a parallel pattern. Finally, the relation map between total demulsification efficiency and the universal flow is drawn, which provides a basis for the accurate control of the IRM device.

Process intensification in vapor–liquid mass transfer: The state-of-the-art

The concept of process intensification(PI) has absorbed diverse definitions and stays true to the mission—'do more with less', which is an approach purposed by chemical engineers to solve the global energy & environment problems. To date, the focus of PI has been on processes mainly involving vapor/liquid systems. Based on the fundamental principles of vapor–liquid mass transfer process like distillation and absorption, there are three strategies to intensify interphase mass transfer: enhancing the overall driving force, improving the mass transfer coefficient and enlarging the vapor–liquid interfacial area. More specifically, this article herein provides an overview of various technologies to strengthen the vapor–liquid mass transfer, including application of external fields, addition of third substances, micro-chemical technology and usage of solid foam, with the objective to contribute to the future developments and potential applications of PI in scientific research and industrial sectors.

SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND COMPRESSION COSTS （PART I：EQUAL TIMES AND COSTS）

Abstract Most papers in scheduling research have treated individual job processing times as fixed parameters. However, in many practical situations, a manager may control processing time by reallocating resources. In this paper, authors consider a machine scheduling problem with controllable processing times. In the first part of this paper, a special case where the processing times and compression costs are uniform among jobs is discussed. Theoretical results are derived that aid in developing an O(n 2) algorithm to slove the problem optimally. In the second part of this paper, authors generalize the discussion to general case. An effective heuristic to the general problem will be presented.

SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND COMPRESSION COSTS ： PROOF OF THEOREMS

Abstract This report is virtually the appendix part of the author's previous paper which includes the proofs for the theorems and lemmas.

晶体倒角工艺改进方法研究

针对非标准尺寸的晶块和晶圆在倒角过程中存在崩边、崩缺等问题,该文通过设计并排式组合夹具和真空吸附盘组件将产品固定,同时设计45°和弧形刀具,然后采用单一直线和正偏移路径进行加工。实验结果表明,与传统的倒角工艺相比,优化能大幅度地降低倒角过程中产生的崩边、崩缺等问题,不合格率从14.78%降低到3.09%,有利于批量生产。

Green microfluidics in microchemical engineering for carbon neutrality

The concept of“carbon neutrality”poses a huge challenge for chemical engineering and brings great opportunities for boosting the development of novel technologies to realize carbon offsetting and reduce carbon emissions.Developing high-efficient,low-cost,energy-efficient and eco-friendly microfluidicbased microchemical engineering is of great significance.Such kind of“green microfluidics”can reduce carbon emissions from the source of raw materials and facilitate controllable and intensified microchemical engineering processes,which represents the new power for the transformation and upgrading of chemical engineering industry.Here,a brief review of green microfluidics for achieving carbon neutral microchemical engineering is presented,with specific discussions about the characteristics and feasibility of applying green microfluidics in realizing carbon neutrality.Development of green microfluidic systems are categorized and reviewed,including the construction of microfluidic devices by bio-based substrate materials and by low carbon fabrication methods,and the use of more biocompatible and nondestructive fluidic systems such as aqueous two-phase systems(ATPSs).Moreover,low carbon applications benefit from green microfluidics are summarized,ranging from separation and purification of biomolecules,high-throughput screening of chemicals and drugs,rapid and cost-effective detections,to synthesis of fine chemicals and novel materials.Finally,challenges and perspectives for further advancing green microfluidics in microchemical engineering for carbon neutrality are proposed and discussed.

The wind-water two-phase erosion and sediment-producing processes in the middle Yellow River basin, China

Based on data from the middle Yellow River basin, a wind-water two-phase mechanism for erosion and sediment-producing processes has been found. By using this mechanism, the extremely strong erosion and sediment yield in the study area can be better explained. The operation of wind and water forces is different in different seasons within a year. During winter and spring, strong wind blows large quantities of eolian sand to gullies and river channels, which are temporally stored there. During the next summer, rainstorms cause runoff that contains much fine loessic material and acts as a powerful force to carry the previously prepared coarse material. As a result, hyperconcentrated flows occur, resulting in high-intensity erosion and sediment yield.

Improvement of signal processing in Coriolis mass flowmeters for gas-liquid two-phase flow

As an increasingly popular flow metering technology,Coriolis mass flowmeter exhibits high measurement accuracy under single-phase flow condition and is widely used in the industry.However,under complex flow conditions,such as two-phase flow,the measurement accuracy is greatly decreased due to various factors including improper signal processing methods.In this study,three digital signal processing methods—the quadrature demodulation(QD)method,Hilbert method,and sliding discrete time Fourier transform method—are analyzed for their applications in processing sensor signals and providing measurement results under gas-liquid two-phase flow condition.Based on the analysis,specific improvements are applied to each method to deal with the signals under two-phase flow condition.For simulation,sensor signals under single-and two-phase flow conditions are established using a random walk model.The phase difference tracking performances of these three methods are evaluated in the simulation.Based on the digital signal processor,a converter program is implemented on its evaluation board.The converter program is tested under single-and two-phase flow conditions.The improved signal processing methods are evaluated in terms of the measurement accuracy and complexity.The QD algorithm has the best performance under the single-phase flow condition.Under the two-phase flow condition,the QD algorithm performs a little better in terms of the indication error and repeatability than the improved Hilbert algorithm at 160,250,and 420 kg/h flow points,whereas the Hilbert algorithm outperforms the QD algorithm at the 600 kg/h flow point.

移动式园林枝条破碎装置设计

随着城市园林的数量不断增多,园林废弃物也不断增多。为了响应资源再利用的号召,可将大量的园林废弃物进行破碎处理后重新利用。但是由于缺乏园林枝条就地破碎装置,废弃枝条通常先收集再运送至处理场集中处理,大大增加人力物力和运输成本。本文设计一款移动式园林枝条破碎装置,通过二级破碎,将破碎颗粒控制在2mm内,满足园林废弃物重复利用需求。

An application of two-phase 1DV model in studying sedimentary processes on an erosional mudflat at Yangtze River Delta, China

A two-phase flow model for predicting sedi- mentation processes under wave and current conditions is presented. The model is based on solving the one- dimensional continuity and momentum equations for both fluid and solid phases through water column （1 DV）. The standard mixing length model is modified to take into account the buoyancy effect due to the gradient of suspended sediments near the seabed. The model is applied to study sedimentation processes on an erosional mudflat in the Yangtze River Delta, China, and intra-tide variations of flow properties and mud concentration are predicted and compared with field measurements. It was found that it is necessary to include the wave-induced shear stress in determining sediment erosion and the existence of a fluid mud layer can significantly influence both the flow structure and the distribution of sediment concentration in the water column. The turbulence dissipation induced by the fluid mud layer has the effect of increasing the duration of re-suspension during the early stage of the ebb. The overall good agreement between measured data and model results demonstrates the capability of the model.

Reliability Evaluation of Two-Phase Degradation Process with a Fuzzy Change-Point

For some products,degradation mechanisms change during testing,and therefore,their degradation patterns vary at different points in time;these points are called change-points.Owing to the limitation of measurement costs,time intervals for degradation measurements are usually very long,and thus,the value of change-points cannot be determined.Conventionally,a certain degradation measurement is selected as the change-point in a two-phase degradation process.According to the tendency of the two-phase degradation process,the change-point is probably located in the interval between two neighboring degradation measurements,and it is a fuzzy variable.The imprecision of the change-point may lead to the incorrect product’s reliability evaluation results.In this paper,based on the fuzzy theory,a two-phase degradation model with a fuzzy change-point and a statistical analysis method are proposed.First,a two-phase Wiener degradation model is developed according to the membership function of the change-point.Second,the reliability evaluation is carried out using maximum likelihood estimation and a fuzzy simulation approach.Finally,the proposed methodology is verified via a case study.The results of the study show that the proposed methodology can achieve more believable reliability evaluation results compared with those of the conventional approach.

轴向载荷下复合材料元件吸能能力的试验研究

试验研究了三种结构形式的复合材料元件在轴向准静态载荷下的压溃过程和能量吸收能力。通过六组试件在轴向准静态载荷下的压溃试验 ,研究复合材料的缓冲吸能机理 ,对吸能能力进行了定义 ,并对试件的峰值载荷。

基于AHP的矿岩爆破破碎性能影响因素分析

为了便于爆破参数选择,建立了矿岩爆破破碎性能影响因素指标体系,应用AHP层次分析法进行定量化分析。结果表明,矿岩的弹性模量、抗压强度、抗拉强度、摩擦角、粘结力为最主要影响因素,权重均为7.93%;炸药威力、猛度(7.04%),炮孔排距、孔底距、一次炸药单耗(6.73%)次之;炮孔偏斜率、超深欠深(2.77%)及矿岩容重(2.54%)影响较小。这为爆破参数选择和爆破设计提供了科学的理论依据。

数字滤波技术在汽车碰撞试验中的应用研究

为了使开发的汽车碰撞试验系统的数据处理结果满足CMVDR294法规要求,研究了汽车碰撞试验数据处理过程中的关键技术.根据汽车碰撞试验的具体要求改进了数字滤波器的设计过程,并应用Matlab进行了不同频率的幅频特性仿真分析,提出了一种能够简化设计过程、提高计算精确性的数字滤波器设计方法,并根据该方法在LabVIEW平台上开发了满足法规要求的数字滤波器.同时,通过对大量的碰撞试验数据进行分析处理,验证了该数字滤波器能够有效屏蔽原始数据中的噪声与高频分量,幅值不失真.

大客车侧翻安全性仿真分析

分析大客车侧翻车身结构安全性研究的意义,建立了侧翻试验仿真流程。用Hy-perMesh建立了整车有限元模型,并用OptiStruct验证了模型的有效性,然后参照ECE R66标准建立侧翻试验台,用能量转换的方法简化碰撞过程,用LS-DYNA进行仿真计算,并引用星级评价方法对结果进行安全性评价。最后对腰身部位的结构进行改进设计,提高了大客车的侧翻安全性。

蛋壳粉补钙面条加工技术研究

对蛋壳粉补钙面条加工技术进行了研究。产品配方和工艺为:在面粉中添加0.6%过200目筛的超微蛋壳粉(以面粉计)和25%～35%的水(以面粉计),和面时间为15～20min,和面温度为30～40℃,面团熟化控制在10～15min,异径滚轧,压延道数6～7道,压片厚度为1.3～1.4mm,再切成2mm的面条,采用中温中速干燥法加工。所得产品外观色泽良好,风味独特,具有较高的保健作用和食疗效果。