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density measurement for plastic injection molding via ultrasonic technology

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0714-2

摘要： Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.

关键词： ultrasonic measurement     melt density     in-situ measurement     injection molding    

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Utilizing melt crystallization fundamentals in the development of a new tabletting technology

Ahmed ABOUZEID,Sandra PETERSEN,Joachim ULRICH

《化学科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 346-352 doi: 10.1007/s11705-014-1443-9

摘要： Increasing production effeciency and lowering costs are some of the many advantages melt crystallization technology offers over the conventional methodology of tabletting. A normal tablet consists of a pure shell or a coat and a separate core constituting the pharmaceutical active ingredient. Great emphasis is put on the purity of the shell since its purpose is to solely protect and deliver the active ingredient to its target. Melt crystallization is a purification (separation) process. It is discussed here for its ability to produce coated tablets, by separating the “coating” material from the “to be coated” material coming from one molten mixture. Molten drops of lutrol-ibuprofen mixture are produced using the drop forming technique. The subsequent analysis involves proving and quantifying the phase separation (coat purity). The mechanism of a crystallizing drop is shown as direct evidence of the ongoing process. Moreover, solidified tablet batches are analyzed for the purity of their coating by measuring the ibuprofen concentration. This optimization process is carried out through multiple stages of development and condition enhancements in order to produce the most pure tablet coating. As a result, a trial showing an almost purely coated tablet is presented here.

关键词： phase separation     melt crystallization     tablets     process optimization    

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Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 435-441 doi: 10.1007/s11705-011-1139-3

摘要： In this paper a porous media seepage model was applied to analyze the permeability and study the seepage process of crystal pillar formed in the preparation of electronic grade phosphoric acid (EGPA). By inspecting the seeping process, the structure parameter of crystal pillar could be obtained. Two basic ideal models (perfectly separated model and perfectly connected model) were presented and a characterized factor was introduced to modify the model. A good simulation result was obtained which met the experiment result well. The relationship between and permeability were also discussed. The characterized factor showed potential application on optimizing process.

关键词： melt crystallization     porous media     fractal     permeability     hyperpure material     simulation    

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Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

《化学科学与工程前沿（英文）》 2010年 第4卷 第3期   页码 263-269 doi: 10.1007/s11705-009-0276-4

摘要： Research on the extrusion of natural polymers (food, feed, etc.) is relatively new due to the complex physicochemical transformations of raw materials, although plastics melt conveying and transport have been well studied. The structure and composition, rheological behavior as well as extrusion processing of natural polymer are much more complicated. In this study, a quasi-three-dimensional (3D) fluid flow model for non-Newtonian, non-isothermal and undeveloped temperature was developed, the model prediction being in reasonably good agreement with the experiment. Results show that the influence of moisture content, among other process variables, is the most significant, followed by screw speed. Some interaction exists between these two variables and the screw speed effect becomes marginal at high moisture contents. In addition, viscosity change in the channel was studied.

关键词： quasi-three-dimensional     rheological     viscosity     processing     influence    

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Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 125-134 doi: 10.1007/s11705-009-0001-3

摘要： The morphology and lateral growth rate of polybutene-1 ( -PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of -PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.

关键词： isotactic polybutene-1     tetragonal phase (form Ⅱ)     melt crystallization     growth rate     kinetic roughening     morphology    

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Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 26-32 doi: 10.1007/s11705-009-0002-2

摘要： Lamellar crystal thickness of isotactic polybutene-1 ( -PB1) have been investigated for crystallization in the melt over a wide range of crystallization temperature from 40°C to 90°C by small angle X-ray scattering experiments and density measurements. The crystal thickness demonstrates two linear dependences on inverse supercooling and a transition from one dependence to the other has been observed around = 65°C. Each of the two dependences obeys the nucleation theory in the high and low supercooling ranges, respectively. Chain folding free energy determined from the low supercooling range is larger than that determined from the high supercooling range. Possible mechanisms for the transition are discussed taking account of entropy of chain folding directions.

关键词： isotactic polybutene-1     tetragonal phase     crystal thickness     melt growth     chain folding     small angle X-ray scattering     nucleation theory     end surface free energy    

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压水堆熔融物堆内滞留策略：历史回顾与研究展望 Review

马卫民,元一单,Bal Raj Sehgal

《工程（英文）》 2016年 第2卷 第1期   页码 103-111 doi: 10.1016/J.ENG.2016.01.019

摘要：

本文对广泛应用于第三代压水堆的严重事故缓解措施——熔融物堆内滞留(IVR)进行了历史回顾。IVR策略最早源自于第二代反应堆Lovissa VVER-440的改进设计，以应对堆芯熔化事故。随后，IVR策略被应用于许多新设计的反应堆，如西屋的AP1000、韩国的APR1400以及中国的先进压水堆CAP1400和华龙一号。对IVR策略有效性影响最大的因素分别为堆内堆芯熔化进程、熔融物加载于压力容器壁面的热流密度和压力容器外部冷却。对于堆芯熔化进程，过去人们一直仅关注压力容器下腔室内熔池的换热行为。但通过回顾与分析，本文认为堆内的其他现象，如堆芯的降级和迁移、碎片床的形成及其可冷却性以及熔池的动态形成过程等，可能也会对熔池的最终状态及其作用于下封头的热负荷产生影响。通过对相关研究的回顾，本文希望找出IVR策略的研究中有待完善的部分，并据目前发展水平提出未来IVR研究的需求。

关键词： 压水堆     严重事故     熔融物堆内滞留     碎片床形成     碎片床再熔化     熔池形成     熔池热工水力学     临界热流密度    

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Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

《机械工程前沿（英文）》 2018年 第13卷 第1期   页码 53-65 doi: 10.1007/s11465-017-0437-y

摘要：

Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the so-called “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

关键词： premature solidification     mold filling     as-cast structure     modeling    

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Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing and melt-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

《化学科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 395-402 doi: 10.1007/s11705-012-1269-2

摘要： A novel phenolic rigid organic filler (named KD) with a high melting point was dispersed in an isotactic polypropylene (iPP) matrix by solution-mixing and/or melt-mixing. A series of KD/iPP blends was prepared with or without addition of maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer. Influences of MAPP and mixing methods on the filler dispersion were studied using polaried optical microscope (POM), scanning electron microscope (SEM) and tensile test. The filler particles are always inclined to form large irregular aggregates in the iPP matrix due to their significant differences in polarity and solubility in solvent. However, an iPP/MAPP/KD (PMK) blend containing filler particles with a quasi-spherical shape (~97.8 nm in diameter) and narrow particle size distribution (polydispersity index= 1.076) was successfully prepared by incorporating MAPP to reduce the interfacial tension and surface free energy between the dispersion phase and the continuous phase, and adopting a spray-drying method after solution-mixing to suppress the increase of the size of the dispersed phase during the removal of solvent.

关键词： dispersion     rigid organic filler     isotactic polypropylene     mixing    

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Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1399-1

摘要：

• With the same charge, current density had little effect on As(III) removal in ACEC.

关键词： Electrocoagulation     Air cathode     Arsenic     Current density     Energy consumption    

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Effects of exercise therapy on bone mineral density in early postmenopausal women: a controlled trial

Shilin DENG MD ,

《医学前沿（英文）》 2009年 第3卷 第3期   页码 323-329 doi: 10.1007/s11684-009-0061-2

摘要： The purpose of this article is to determine the effect of a well-designed combined aerobic, resistance, and extension exercise program on bone mineral density (BMD) in postmenopausal women. The population comprised 45 postmenopausal women, who exercised over 12months (exercise group), and 36 women who served as a non-training control group. BMD of the hip, and lumbar spine was measured at the baseline and 12th month. Repeated measurement analysis of variance and nonparametric test were utilized to compare differences between the exercise group and controls. Thirty-six out of 45 persons in the exercise group and 36 controls completed the study. Average compliance was 82.2% for the whole exercise group at the 12th month. All the subjects had decreased BMD, but the rate of bone loss was lower in the exercise group than in the control group at the L4 and hip. Although the exercise program in this study may probably reduce the rate of bone loss in weight-bearing skeletal sites, we do not suggest the exercise by itself be viewed as prevention or treatment for osteoporosis. Further, the exact dose-response relationship of exercise and bone mass in early postmenopause is not clear.

关键词： early postmenopausal women     bone mineral density     exercise     effects    

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Relationship of adrenomedullin expression and microvessel density and prognosis in smooth muscle tumor

JIANG Yuan, TIAN Xuehong, YUAN Jie, JIN Yuemei, TAN Yusong

《医学前沿（英文）》 2007年 第1卷 第4期   页码 398-400 doi: 10.1007/s11684-007-0077-4

摘要： The aim of this paper was to investigate the relationship between the expression of adrenomedullin (ADM) and microvessel density (MVD) and prognosis in smooth muscle tumor of uterus. The expression of ADM was detected using immunohistochemical staining in specimens from 15 normal controls, 28 cases of uterine leiomyoma (LE) and 19 cases of uterine leiomyosarcoma (LES). The MVD was assayed by immunostainting with CD. There was a positive correlation between the ADM expression and MVD in LE and LES respectively ( = 0.823, <0.01; = 0.793, <0.01). The expression of ADM in LE was statistically lower than that in LES (<0.05). There was a positive correlation between the ADM expression and mitotic figures in LES (<0.05): the more mitotic figures, the higher levels of the ADM expression and poor prognosis. The ADM is an important angiogenic factor in smooth muscle tumor of uterus. The ADM can be used as an accessory marker in estimating the malignant potency of LE and judging the pro gnosis of LES, and as a novel molecular target of anti-angiogenic and anticarcinogenic strategies.

关键词： anticarcinogenic     microvessel density     malignant potency     muscle     uterine leiomyosarcoma    

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Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

《机械工程前沿（英文）》 2021年 第16卷 第1期   页码 186-195 doi: 10.1007/s11465-020-0608-0

摘要： This paper presents a single-electromagnet levitation device to measure the densities and detect the internal defects of antimagnetic materials. The experimental device has an electromagnet in its lower part and a pure iron core in the upper part. When the electromagnet is activated, samples can be levitated stably in a paramagnetic solution. Compared with traditional magnetic levitation devices, the single-electromagnet levitation device is adjustable. Different currents, electromagnet shapes, and distances between the electromagnet and iron core are used in the experiment depending on the type of samples. The magnetic field formed by the electromagnet is strong. When the concentration of the MnCl aqueous solution is 3 mol/L, the measuring range of the single-electromagnet levitation device ranges from 1.301 to 2.308 g/cm . However, with the same concentration of MnCl aqueous solution (3 mol/L), the measuring range of a magnetic levitation device built with permanent magnets is only from 1.15 to 1.50 g/cm . The single-electromagnet levitation device has a large measuring range and can realize accurate density measurement and defect detection of high-density materials, such as glass and aluminum alloy.

关键词： single-electromagnet     electromagnetic levitation     density measurement     defect detection    

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Application of gamma-ray attenuation technology in density measurement of a slurry reactor

Jian XU, Weisheng WEI, Kai ZHANG

《化学科学与工程前沿（英文）》 2010年 第4卷 第4期   页码 486-490 doi: 10.1007/s11705-010-0509-6

摘要： Axial density profile of the gas-liquid-solid mixture in a slurry bubble column was measured by gamma-ray attenuation technology. Several measures for improving measurement precision were presented based on the discussion on attenuation law. It was found that the response frequency and the ray intensity should be as high as possible to improve the measurement precision. The mass absorption coefficient depended on not the object’s thickness but the location where the object was placed between the ray source and the detector. The results showed that the density in the column decreases with the increase of column height, which indicates that the measurement by gamma-ray attenuation is reasonable.

关键词： slurry reactor     axial density distribution     gamma-ray attenuation technology    

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Development of lunar regolith-based composite for - 3D printing via high-pressure extrusion system

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0745-8

摘要： To fully utilize the in-situ resources on the moon to facilitate the establishment of a lunar habitat is significant to realize the long-term residence of mankind on the moon and the deep space exploration in the future. Thus, intensive research works have been conducted to develop types of 3D printing approach to adapt to the extreme environment and utilize the lunar regolith for in-situ construction. However, the in-situ 3D printing using raw lunar regolith consumes extremely high energy and time. In this work, we proposed a cost-effective melting extrusion system for lunar regolith-based composite printing, and engineering thermoplastic powders are employed as a bonding agent for lunar regolith composite. The high-performance nylon and lunar regolith are uniformly pre-mixed in powder form with different weight fractions. The high-pressure extrusion system is helpful to enhance the interface affinity of polymer binders with lunar regolith as well as maximize the loading ratio of in-situ resources of lunar regolith. Mechanical properties such as tensile strength, elastic modulus, and Poisson’s ratio of the printed specimens were evaluated systematically. Especially, the impact performance was emphasized to improve the resistance of the meteorite impact on the moon. The maximum tensile strength and impact toughness reach 36.2 MPa and 5.15 kJ/m2, respectively. High-pressure melt extrusion for lunar regolith composite can increase the effective loading fraction up to 80 wt.% and relatively easily adapt to extreme conditions for in-situ manufacturing.

关键词： in-situ resource utilization     melt extrusion molding     lunar regolith-based composites     mechanical properties     additive manufacturing    

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标题 作者 时间 类型 操作

density measurement for plastic injection molding via ultrasonic technology

期刊论文

Utilizing melt crystallization fundamentals in the development of a new tabletting technology

Ahmed ABOUZEID,Sandra PETERSEN,Joachim ULRICH

期刊论文

Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

期刊论文

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

期刊论文

Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

期刊论文

Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

期刊论文

压水堆熔融物堆内滞留策略：历史回顾与研究展望

马卫民,元一单,Bal Raj Sehgal

期刊论文

Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

期刊论文

Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing and melt-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

期刊论文

Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

期刊论文

Effects of exercise therapy on bone mineral density in early postmenopausal women: a controlled trial

Shilin DENG MD ,

期刊论文

Relationship of adrenomedullin expression and microvessel density and prognosis in smooth muscle tumor

JIANG Yuan, TIAN Xuehong, YUAN Jie, JIN Yuemei, TAN Yusong

期刊论文

Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

期刊论文

Application of gamma-ray attenuation technology in density measurement of a slurry reactor

Jian XU, Weisheng WEI, Kai ZHANG

期刊论文

Development of lunar regolith-based composite for - 3D printing via high-pressure extrusion system

期刊论文