金属注射成形过程中的粉末堆积问题

本文综述了金属注射成形中颗粒及粉末堆积的研究状况，对双组元球形颗粒的数学模型的理论基础、基本概念和方法作了比较详细的介绍和分析，并扼要介绍了连续粒径分布的颗粒堆积和影响粉末—粘结剂的装载量大小的因素。     

A novel approach using Dynamic Social Impact Theory for optimization of impedance-Tongue (iTongue)

This paper presents a novel multiobjective wrapper approach using Dynamic Social Impact Theory based optimizer (SITO). A Fuzzy Inference System in conjunction with support vector machines classifier has been used for the optimization of an impedance-Tongue for the classification of samples collected from single batch production of Kangra orthodox black tea. Impedance spectra of the tea samples have been measured in the range of 20 Hz to 1 MHz using a two electrode setup employing platinum and gold electrodes. The proposed approach has been compared, for its robustness and validity using various intra and inter measures, against Genetic Algorithm and binary Particle Swarm Optimization. Feature subset selection methods based on the first and second order statistics have also been employed for comparisons. The proposed approach outperforms the Genetic Algorithm and binary Particle Swarm Optimization.     

Wastewater renovation using constructed soil filter (CSF): A novel approach

Constructed soil filter (CSF) also known as Soil Biotechnology (SBT) is a process for water renovation which makes use of formulated media with culture of soil macro- and microorganisms. CSF combines sedimentation, infiltration and biodegradation processes to remove oxidizable organics and inorganics of wastewater in a single facility. Operating experience shows hydraulic loading in the range of 0.05–0.25 m³/m² h and organic loading up to 200–680 g/m² d. The results show increase in dissolved oxygen levels, COD removal (from 352 mg/l to 20 mg/l); BOD removal (from 211 mg/l to 7.0 mg/l); suspended solids removal (from 293 mg/l to 16 mg/l); turbidity reduction (from 145 NTU to 5.3 NTU); iron (from 5 mg/l to 0.3 mg/l); arsenic (from 500 μg/l to 10 μg/l); total coliform and fecal coliform removal (from 145 × 10⁵ to 55 CFU/100 mL and 150 × 10⁸ to 110 CFU/100 mL respectively), with desired pathogen levels as per WHO standards, i.e. ≤10³ CFU/100 mL. CSF reveals advantages such as low HRT (0.5–2.0 h), low energy requirement (0.04 kW h/m³), no pre-treatment, high dissolved oxygen levels in the effluent, no biosludge production, no mechanical aeration and no odor, fish compatible water quality and evergreen ambience.     

A Methodology for the Design of Effective Cooling System in Injection Moulding

In this work, the forming behaviour of a commercial sheet of AZ31B magnesium alloy at elevated temperatures is investigated and reported. The experimental activity is performed in two phases. The first phase consists in free bulging test and the second one in analysing the ability of the sheet in filling a closed die. Different pressure and temperature levels are applied. In free bulging tests, the specimen dome height is used as characterizing parameter; in the same test, the strain rate sensitivity index is calculated using an analytical approach. Thus, appropriate forming parameters, such as temperature and pressure, are individuated and used for subsequent forming tests. In the second phase, forming tests in closed die with a prismatic shape cavity are performed. The influence of relevant process parameters concerning forming results in terms of cavity filling, fillet radii on the final specimen profile are analysed. Closed die forming tests put in evidence how the examined commercial magnesium sheet can successfully be formed in complicated geometries if process parameters are adequately chosen.     

A novel X-ray technique for inspection of steel pipes

The corrosion-induced material loss in crude oil carrying steel pipelines was originally studied by making use of the backscatter X-ray technique. The steel thickness can be determined by studying the density profile of the backscatter intensity vs. the depth location of a voxel. There are, however, some practical limitations to the above method, and a new method for evaluating steel thickness, namely, the transcatter technique is described. This technique uses the intensity of the beam which is transmitted by the pipe wall and subsequently scattered by the hydrocarbon inside the pipeline. The thickness is evaluated using three techniques, namely, the sequential technique, the dual angle technique, and the reference technique. Of the three techniques, the sequential technique has been studied in detail. The mathematical equations and experimental results related to the transcatter technique show that the thickness can be measured with an accuracy of better than 10% for a nominal steel thickness of 8 mm with a measurement time of several minutes.     

Adaptive crosshatch approach for the laminated object manufacturing (LOM) process

The waste material removal process of laminated object manufacturing (LOM), so-called 'decubing', is a labour-intensive and time-consuming work resulting from the commonly used uniform crosshatch setting. An adaptive crosshatch approach to improve working efficiency and alleviate the effort involved in the decubing process is developed. The working region is divided into two portions, the inner region and the outer region, by the proposed rectangle and original contour offset approaches. The fine crosshatch pattern is designated to the inner region based on the shape of the cross-section contour, and the rules to select crosshatches for different shapes are given. The outer region has a coarse crosshatch pattern, and it is an integer multiple of that of the inner region. The brick-layered effect in the overlap zone of the waste material is eliminated by the projection method. Experiments show that with the adaptive crosshatch approach there are four major advantages: saving laser power consumption, protecting the part from damage, improving machining efficiency and easier decubing.     

Measuring long-term performance of a manufacturing firm using the Analytic Network Process (ANP) approach

This paper provides a multicriteria performance measurement model to measure a manufacturing firm's performance in terms of areas of success, which can be defined as critical areas in generating revenues and controlling costs in the operations of a manufacturing firm. In developing the performance measurement model, the Analytic Network Process (ANP) approach is used. The ANP approach, which is the general form of the Analytic Hierarchy Process (AHP) methodology, is recommended when independence among different elements of a system assumption is violated. In a manufacturing system, the system's attributes are interrelated. Furthermore, the relative importance of these attributes with respect to each other and their contribution to the overall performance are affected by the competitive strategies applied by the manufacturing firms. The performance evaluation model developed here incorporates the competitive strategies and interdependence between the system attributes in its hierarchical structure and achieves a more realistic and accurate representation of the firm's long-term performance.     

A study concerning the characteristic of capillary-porous wicks for low-temperature heat pipes

A method is described and results are shown of measuring the characteristics of capillaryporous wicks for heat pipes on a single test stand.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 4, pp. 606–611, October, 1972.     

A differentiated approach for justification of advanced manufacturing technologies

European companies rely on advanced manufacturing technologies (AMTs) in order to succeed in an environment of high labour costs, increasing competition and rising customer expectations. AMT implementation is often a high-risk investment. Many companies experience a misalignment between the installed functionality and production needs. There is a need for decision support in order to take into account all possible advantages and disadvantages of the technology implementation, and ensure that the technology meets the requirements of the production processes. In this article, a differentiated technology justification approach is introduced. The approach suggests a combination of strategic, financial and risk justification methods. The recommended number and type of methods depend on the integration level of the technical system under consideration, ranging from stand-alone machines to large and integrated production systems. The approach was developed based on a literature review and a case study. The application of the approach was presented in a case where several types of pipe bending technology were evaluated.     

一种压力波驱动的非共振型直流换热器的工作原理及实验

分析了传统交流型换热器的不足,提出了一种压力波(声波)驱动的非共振直流型换热器,对其基本工作原理进行了阐述,建立了原理性实验系统,初步研究了其换热性能,验证了该换热器用于交变流动热力系统的可行性.     

A novel electromagnetic design and a new manufacturing process for the cavity BPM (Beam Position Monitor)

The Cavity Beam Position Monitor (BPM) is a beam diagnostic instrument which, in a seeded Free Electron Laser (FEL), allows the measurement of the electron beam position in a non-destructive way and with sub-micron resolution. It is composed by two resonant cavities called reference and position cavity, respectively. The measurement exploits the dipole mode that arises when the electron bunch passes off axis. In this paper we describe the Cavity BPM that has been designed and realized in the context of the FERMI@Elettra project [1]. New strategies have been adopted for the microwave design, for both the reference and the position cavities. Both cavities have been simulated by means of Ansoft HFSS [2] and CST Particle Studio [3], and have been realized using high precision lathe and wire-EDM (Electro-Discharge) machine, with a new technique that avoids the use of the sinker-EDM machine. Tuners have been used to accurately adjust the working frequencies for both cavities. The RF parameters have been estimated, and the modifications of the resonant frequencies produced by brazing and tuning have been evaluated. Finally, the Cavity BPM has been installed and tested in the presence of the electron beam.     

A new inverse analysis approach for multi-region heat conduction BEM using complex-variable-differentiation method

This paper presents a new inverse analysis approach for identifying material properties and unknown geometries for multi-region problems using the Boundary Element Method (BEM). In this approach, the material properties and coordinates of an unknown region boundary are taken as the optimization variables, and the sensitivity coefficients are computed by the Complex-Variable-Differentiation Method (CVDM). Due to the use of CVDM, the sensitivity coefficients can be accurately determined in a way that is as simple to use as the Finite Difference Method (FDM) and an inverse analysis for a complex composite structure can be easily performed through a similar procedure to the direct computation. Although basic integral equations are presented for heat conduction problems, the application of the proposed algorithm to other problems, such as elastic problems, is straightforward. Two numerical examples are given to demonstrate the potential of the proposed approach.     

A novel approach for high-quality microarray processing using third-dye array visualization technology

Historically, microarray image processing has been technically challenging in obtaining quality gene expression data. After hybridization of Cy3- and Cy5-labeled samples, images are collected and processed to obtain gene expression ratio measurements for each of the elements on the array. The hybridization process often brings in contaminating noise, which can make correct identification of the signal difficult. In addition, spot intensity levels are highly variable due to the expression differences of different genes, and weak spots are often difficult to detect. These conditions are further complicated by inherent irregularities in spot position, shape, and size commonly found on high-density microarrays, making image processing an often labor-intensive task that is difficult to reliably automate. We previously reported a novel third-dye array visualization (TDAV) technology that allows prehybridization visualization and quality control of printed arrays. Here, we present a new microarray image processing approach utilizing TDAV. By incorporating the third-dye image, we show that overall quality of the microarray data is significantly improved, and automation of processing is feasible and reliable. Furthermore, we demonstrate use of the third-dye image to better quality control microarray image analysis. Both the principle and implementation of the approach are presented in detail, with experimental results.     

Microthermoforming as a novel technique for manufacturing scaffolds in tissue engineering (CellChips)

The CellChip is a microstructured polymer scaffold, which favours a three-dimensional cultivation of cells within an array of cubic microcontainers. The manufacturing process used so far is microinjection moulding combined with laser-based perforation. In a first attempt to simplify the process, costly perforation was avoided by using commercially available, inexpensive microfiltration membranes for the bottom of the microcavities. Microthermoforming is a promising novel technique which allows the CellChip to be produced from thin film. Working pressures of approximately 4000 kPa were required for the adequate moulding of 50 microm thick films from three different polymers (polystyrene, polycarbonate, cyclo-olefin polymer). Integrating drafts and chamfers in micromoulds is not going to eliminate an uneven thickness profile, but reduces demoulding forces. Microthermoformed CellChips of polycarbonate were perforated by an ion track technique to guarantee a sufficient supply of medium and gases to the cells. The prestructured CellChips were irradiated with 1460 MeV xenon ions at a fluence of a few 10(6) ions/cm2. The tracks were etched in an aqueous solution of 5 N NaOH at 30 degrees C, which resulted in cylindrical pores approximately 2 microm in diameter. Microinjection-moulded, membrane-bonded and thermoformed CellChips were subjected to comparative examination for viability in a cell culture experiment with parenchymal liver cells (HepG2). The cells stayed viable over a period of more than 20 days. No significant differences in viability between injection-moulded, membrane-bonded, and thermoformed CellChips were observed.     

Metal dusting (catastrophic carburization) of a waste heat boiler tube

A waste-heat boiler at a chemical plant suffered an unusual tube failure. The boiler is part of the partial oxidation (POx) syngas production for a 2-ethyl hexanol unit. The syngas primarily consists of H₂, CO and CO₂ with trace amounts of CH₄. Steam is also reportedly injected into the process. The syngas enters the boiler at approximately 1800°F (980°C) on the internal side of the tube and is cooled, while generating approximately 640 psi (4.41 MPa) steam at 490°F (255°C) on the outside of the tube. The internal surface of the tube contained a region of metal loss that was approximately 1 inches long by inch wide (44.5 mm by 19 mm). The metal loss was very localized with little evidence of attack elsewhere on the tube's surface. Molten salt attack, sulfidation and metal dusting were considered as possible mechanisms for the metal loss. It was determined that metal dusting, also called catastrophic carburization, was the cause of the metal loss. The cause of the metal dusting was localized overheating of the tube, which developed because of water/steam flow disruption due to contact of the tube baffle with the tube. Approximately one year after this tube failure, the boiler suffered two more tube failures, which were also attributed to metal dusting.     

Framework for the control of automated material-handling systems using the holonic manufacturing approach

In today's global economy, manufacturing companies must be able to change both the product variety and production quantity without incurring major disturbances in the production process. A manufacturing system capable of performing these changes efficiently needs a control system flexible enough to go from one state to another without significant delays in production. To compensate for the deficiencies of both hierarchical and heterarchical control systems, a control architecture based on the holonic concept is proposed. After presenting the general holonic control architecture, the paper focuses on the integration of the holonic-based control concept in the design of an automated material-handling control system. When performing transport activities in a manufacturing system, due to its architecture, the holonic system can operate both as a hierarchical system, following a predefined schedule during normal operation conditions, and as a heterarchical system in the presence of disturbances.     

A novel approach for the biosynthesis of silver oxide nanoparticles using aqueous leaf extract of Callistemon lanceolatus (Myrtaceae) and their therapeutic potential

This study describes a novel biological route for the biosynthesis of silver oxide nanoparticles utilising the aqueous extract of Callistemon lanceolatus D.C. leaves. Formation of silver oxide nanoparticles was confirmed by UV–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope–energy dispersive X-ray spectroscopy and X-ray diffraction spectroscopy analysis. The biologically synthesised silver oxide nanoparticles were found to be 3–30 nm in size with spherical and hexagonal shape by high-resolution transmission electron microscope analysis. Furthermore, the biogenic silver oxide nanoparticles demonstrated significant (p?in vitro antioxidant methods. These particles also exhibited significant (p?相似文献   

新型通用级苯酚-淀粉模塑料(PF2A1)的研制

研制的产品典型配方(质量份)是苯酚-淀粉树脂:六次甲基四胺:木粉:碳酸钙:氧化镁:硬脂酸锌:硬脂酸:油溶苯胺黑:群青=37.0:6.4:48.0:6.0:0.6:0.6:0.4:0.5:0.5;制备工艺参数是混合时间≥60min,工作辊温度85～95℃,空转辊温度145～155℃,辊距2.3～2.5mm,热炼时间4～5min,拼批时间≥45min;模塑工艺参数是预热温度100～110℃,预热时间10～15min,模塑压力≥25MPa,模塑温度175～180℃,模塑时间0.8～1.0min/mm,排气≥3次.产品性能达到酚醛模塑料(PF2A1)国家标准或优良,原料成本比苯酚-甲醛模塑料(PF2A1)低20.4%.     

A novel pilot-scale production of fuel gas by allothermal biomass gasification using biomass micron fuel (BMF) as external heat source

A novel pilot-scale allothermal biomass gasification system integrating steam gasification, thermal cracking, and catalytic reforming aiming at fuel gas production was developed. Biomass micron fuel (BMF) was used as external heat source by combusting with air in the combustor. Biomass feedstock was gasified with steam, and then, tar in the produced gas was decomposed by thermal cracking and catalytic reforming. The waste heat of high-temperature flue gas and fuel gas was recovered and used for biomass feedstock pre-heating and steam generation, respectively. The fuel gas yield is 1.36 Nm³/kg with lower heating value of 11.61 MJ/Nm³. An overall energy analysis of the system was also investigated. The results showed that the cold gas efficiency and energy conversion efficiency in this system are 88.11 and 63.59 %, respectively. Meanwhile, combustion of BMF accounts for 25.66 % of the total energy input.     

A fracture mechanics approach for the prediction of the failure time of polybutene pipes

In this work two grades of Isotactic polybutene-1 with a different degree of isotacticity have been investigated; fracture tests have been performed at various temperatures and testing speeds on DCB and SENB samples. Optical methods have been used to record crack advancement.Results of the tests have been interpreted using the fracture mechanics framework; a time–temperature superposition scheme has been adopted to describe crack propagation behaviour over several decades of time-scale. An analytical model has been applied to predict the lifetime of pressurised pipes from experimental fracture data. There is good agreement between model predictions and experimental data obtained from full-scale tests on real pipes.