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A review of selective laser melting of aluminum alloys: Processing,microstructure, property and developing trends

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Journal of Materials Science & Technology 2019年第2期35卷 270-284页

作者： Jinliang Zhang Bo Song Qingsong Wei Dave Bourell Yusheng Shi State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Dave Bourell Laboratory for Freeform Fabrication Mechanical Engineering Department The University of Texas at Austin

Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural materials, is well known for high specific strength and good corrosion resistance. But the poor laser formability of aluminum alloy restricts its application. There are problems such as limited processable materials, immature process conditions and metallurgical defects on SLM processing aluminum alloys. Some efforts have been made to solve the above problems. This paper discusses the current research status both related to the scientific understanding and technology applications. The paper begins with a brief introduction of basic concepts of aluminum alloys and technology characterization of laser selective melting. In addition, solidification theory of SLM process and formation mechanism of metallurgical defects are discussed. Then, the current research status of microstructure, properties and heat treatment of SLM processing aluminum alloys is systematically reviewed respectively. Lastly, a future outlook is given at the end of this review paper.

关键词： Selective laser melting Aluminum alloy Metallurgical defects Mechanical properties Heat treatment developing trend

developing stages and causes of desertification in the Mu Us sandland

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Chinese Science Bulletin 1999年第9期44卷 845-849页

作者： Bo Wu Longjun Ci Chinese Acad Forestry Chinese Res & Dev Ctr Combating Desertificat Beijing 100091 Peoples R China

Based on historical aerial photography of three periods and together with field investigation, the status of desertification development after the 1950s in the Mu Us sandland was analyzed, the difference of the desertification developing speed at two stages was compared, and its possible causes were explored. The results show that the developing speed of desertification from the late 1970s to the early 1990s is apparently slowed down, compared with that from the late 1950s to the late 1970s and there exists an obvious recovery trend at the second stage. The difference between the two stages accounts for severely over-reclaiming, over-grazing and unrestricted cutting during the first stage, which are the main causes of desertification development in the semi-arid steppe and arid desert steppe areas.

关键词： Mu Us sandland desertification developing stage over-reclaiming over-grazing unrestricted cutting.

Hepatitis B:Epidemiology and prevention in developing countries

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World Journal of Hepatology 2012年第3期4卷 74-80页

作者： Elisabetta Franco Barbara Bagnato Maria Giulia Marino Cristina Meleleo Laura Serino Laura Zaratti Department of Public Health University Tor Vergata PhD Program for Methodologies in Preventive Medicine and Therapy University Tor Vergata Specialization School for Hygiene and Preventive Medicine University Tor Vergata

Hepatitis B virus(HBV)infection is a serious global public health problem.The infection may be transmitted through sexual intercourse,parenteral contact or from an infected mother to the baby at birth and,if contracted early in life,may lead to chronic liver disease,including cirrhosis and hepatocellular carcinoma.On the basis of the HBV carrier rate,the world can be divided in 3 regions of high,medium and low endemicity.The major concern is about high endemicity countries,where the most common route of infection remains vertical transmission from mother to child.Screening of all pregnant women and passive immunization with human hepatitis B immunoglobulin are not affordable for many developing countries.The infection rate can be reduced by modifying behavior,improving individual education,testing all blood donations,assuring asepsis in clinical practice and screening all pregnant women.However,availability of a safe and efficacious vaccine and adoption of appropriate immunization strategies are the most effective means to prevent HBV infection and its consequences.The unsolved problem for poorest countries,where the number of people currently infected is high,is the cost of the vaccine.A future challenge is to overcome the social and economic hurdles of maintaining and improving a prevention policy worldwide to reduce the global burden of the disease.

关键词： Hepatitis B developing countries Endemicity Seroprevalence Vaccine

The microbial content of unexpired pasteurized milk from selected supermarkets in a developing country

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Asian Pacific Journal of Tropical Biomedicine 2011年第3期1卷 205-211页

作者： Melisa Anderson Patrice Hinds Stacyann Hurditt Princena Miller Donovan McGrowder Ruby Alexander-Lindo Department of Pathology Faculty of Medical SciencesUniversity of the West Indies School of Allicd Health and Nursing College of Health SciencesUniversity of Technology Department of Basic Medical Sciences Faculty of Medical SciencesUniversity of the West Indies

Objective:To determine the presence and levels of microbes in unexpired pasteurized milk from randomly selected supermarkets in Kingston,Jamaica.Methods:The quantitative study used a stratified random sampling technique in the selection of the 20 representative milk samples from six(6) supermarkets.Microbiological tests such as methylene blue reduction,standard plate count(SPC),coliform plate count(CPC),purity plate culture,gram staining and biochemical tests were performed to examine the microbes in purchased unexpired pasteurized milk.Results:One sample(BCr016) had a pH of 4.0.a rancid odour and curdled appearance.It decolourized within one hour during the methylene blue reduction test and was classified as class 4 milk.Seven of the samples were sterile with no microbe growth on the plate count agar and violet red bile salt agar(VRBA).The milk samples that appeared to be safe for consumption were all 10,11,12 and 13 days before expiration.The VRBA sample BCr016,had a colony count of 13 400 CFU/ mL.There was the presence of Escherichia coli in sample LCr021 which had a standard plate count of 1 580 SPC/mL and a coliform count of 500 CFU/mL.Enterobacter sp.was present in colonies from BCr016 and all the other milk samples.Conclusions:Unacceptable levels of Entembacter spp.and Escherichia coli were found in most of the samples.Effective measures to ensure safe milk for human consumption such as the phosphatase test and methylene blue reduction test should be routinely performed on each batch of milk processed by dairy plants.

关键词： Microbial content Pasteurized milk Supermarkets Microbe Microbiological test Escherichia coli Enterobacter spp Milk Dairy plant developing country

Hepatitis A:Epidemiology and prevention in developing countries

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World Journal of Hepatology 2012年第3期4卷 68-73页

作者： Elisabetta Franco Cristina Meleleo Laura Serino Debora Sorbara Laura Zaratti Department of Public HealthUniversity Tor Vergata Specialization School for Hygiene and Preventive Medicine University Tor Vergata

Hepatitis A is the most common form of acute viral hepatitis in the world.Major geographical differences in endemicity of hepatitis A are closely related to hygienic and sanitary conditions and other indicators of the level of socioeconomic development.The anti-hepatitis A virus(HAV)seroprevalence rate is presently decreasing in many parts of the world,but in less developed regions and in several developing countries,HAV infection is still very common in the first years of life and seroprev-alence rates approach 100%.In areas of intermediate endemicity,the delay in the exposure to the virus has generated a huge number of susceptible adolescents and adults and significantly increased the average age at infection.As the severity of disease increases with age,this has led to outbreaks of hepatitis A.Several factors contribute to the decline of the infection rate,including rising socioeconomic levels,increased access to clean water and the availability of a hepatitis A vaccine that was developed in the 1990s.For populations with a high proportion of susceptible adults,implementing vaccination programs may be considered.In this report,we review available epidemiological data and implementation of vaccination strategies,particularly focusing on developing countries.

关键词： Hepatitis A developing countries Endemic-ity Seroprevalence Vaccine

Modeling Open Software Architectures of Robot Controllers: A Brief Survey of Modeling Methods and developing Methods

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High Technology Letters 2002年第4期8卷 74-79页

作者：徐华 Jia Peifa Zhao Yannan State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing 100084 P.R.China

Openness is one of the features of modern robot controllers. Although many modeling technologies have been discussed to model and develop open robot controllers, the focus is always on modeling methodologies. Meanwhile, the relations between the former and the latter are usually ignored. According to the general software architecture of open robot controllers, this paper discusses modeling and developing methods. And the relationships between the typical ones are also analyzed.

关键词： robotics, modeling methodology, developing methodology, robot controller, openness

developing EBay Business Tools For Dummies (For Dummies (Business & Personal Finance))

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THE developing METHOD OF AI SOFTWARE FOR APPLICATION OF AERIAL PHOTOGRAPH(AIAAP)

2005年

作者： John Kaufeld Tim Harvey

ISBN: (纸本)9780764579066

Features ready-to-use applications-all available on the CD-ROM-that eBay sellers can plug right into their pages; more advanced users can tweak the applications to suit specific needsShows you how to streamline an eBay business by leveraging programming technologies and the eBay API (application program interface)Explains how to connect eBay pages to the APIs of related companies (PayPal, Fed Ex, UPS, and the USPS) as well as to Microsoft Office applications such as Outlook and ExcelProvides expert tips and tricks for implementing eBay technologies such as image handling, shipping calculators, enhanced About Me pages, and back-office tools

关键词： business dummies personal tools ebay developing

来源：畅想之星图书光盘版（南... 评论

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Journal of Northeast Forestry University 1995年第4期6卷 28-31页

作者：朱峰范文义 Northeast Forest University China

This paper put forward a framework of artificial intelligence (AI) for app;ication of aerial photograph. The framwork contains structures of knowledge base and inference mechanism.The functions of framework about how to convert expert’s knowledge into logical rules and how to inference using the rules wer discussed. The regeneraion pltring of fired land in Dwi’an Mountains area was taken as an example to have a ditail discuss on the contation of knowledge base and the steps of inference mechaism. the program was written using the basic langUae and the running result proyed tha the software can take the place of expert’s work with high efficiellcy.

关键词： developing method Artificial intelligence Knowledge base Inference mechanism

BASIC FIBROBLAST GROWTH FACTOR （bFGF） IMMUNOREACTIVITY IN developing GRANULATION TISSUE ：ANIMMUNOHISTOCHEMICAL STUDY

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中华创伤杂志 1995年第6期 84-88页

Ｉｎｓｅｖｅｒｅｔｒａｕｍａａｎｄｂｕｒｎ，ｔｈｅｏｖｅｒｇｒｏｗｔｈｏｆｇｒａｎｕｌａｔｉｏｎｔｉｓｕｅｗｉｌｄｅｖｅｌｏｐｉｎｔｏｅｘｃｅｓｉｖｅｓｃａｒ，ｗｈｉｃｈｒｅｐｒｅｓｅｎｔｓａｍａｌａｄａｐｔｉｖｅｒ... 详细信息

Ｉｎｓｅｖｅｒｅｔｒａｕｍａａｎｄｂｕｒｎ，ｔｈｅｏｖｅｒｇｒｏｗｔｈｏｆｇｒａｎｕｌａｔｉｏｎｔｉｓｕｅｗｉｌｄｅｖｅｌｏｐｉｎｔｏｅｘｃｅｓｉｖｅｓｃａｒ，ｗｈｉｃｈｒｅｐｒｅｓｅｎｔｓａｍａｌａｄａｐｔｉｖｅｒｅｓｐｏｎｓｅｔｏｔｉｓｕｅｒｅ┐...

关键词： BASIC developing FACTOR FIBROBLAST GRANULATION GROWTH IN STUDY TISSUE