A Laser Induced Liquid Phase Reaction Synthesis Assisted Joining technique is employed for SiC-particulate/Al-alloy composite to produce joints. Joints in SiC/Al-alloy composite are produced by synthesis of suitable material product as a result of interaction between composite and Ti (or Ti-alloy) reactive filler material induced by laser energy in the joint region. Such reaction product minimizes or eliminates the formation of deleterious aluminum carbide phase in the joint region depending upon the type and nature of die interfacial reactive filler material and also the laser processing parameters. A laser beam is utilized to both synthesize the interfacial reactant mixture and to heat the base material adjacent to the joint region to minimize the thermal stresses. The technique along with suitable filler material, further can be extended to a variety of metal matrix composite systems including combinations of Gr/Al, B/Al, B4C/Mg, Steel/Al, W/Al, Al2 O3 and Gr/Cu which are excellent for use in various automotive, aerospace and electronic applications. Preliminary observations describing the proof of concept of laser induced reaction joining of metal matrix composites are reported 相似文献
This study investigated the effectiveness of different types of on-line feedback following user errors for informing users of the information and functions available in a system with a natural language interface. Twenty-four individuals performed a task based on an industry cost savings program, in which they were given general goals to pursue with regard to the task. Three feedback levels which differed according to the type and amount of feedback provided, along with two levels of system complexity, were examined. In addition, subjects performed the task again after one week to determine the effects of feedback on retention. Results indicated that the subjects in the second level of feedback generally performed better with respect to accessing system functions and information than those in the first level. Although there was some performance improvement from the second to third level, it was not significant. However, the third level of feedback did significantly improve the efficiency with which subjects used information to complete the task during the return condition. Overall, feedback did not affect the errors made, though at certain more limited stages of the tasks this effect was observed. 相似文献
Contends that tests in repeated-measures designs based on MANOVA are free of sphericity assumptions, and with modern computing software, MANOVA is straightforward to use, even for complex designs and nontraditional hypotheses. A general strategy for implementing MANOVA within statistical computing packages is presented. Regular (preplanned) tests and simultaneous (post hoc) tests are illustrated for a variety of designs and hypotheses. Optimal contrasts for unbalanced repeated measures designs are appended. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
The electronic mail (EM) network in a large, multi-campus community college district was used by some employees to gain support for positions contrary to those of the leadership. The case study offered an opportunity to look at technology within an organizational setting. It raised questions about the loose coupling of the educational organization's technical and authority systems, about the strength of coupling among employee groups during the incident, about the boundaries of the EM political activists, and about the power manifested within educational organization's technical and authority systems. A variety of research methods (stages of event progression, fantasy types associated with consciousness-building, and evidence of user technical and rhetorical skills) were used to answer questions about the organization's loosely coupled systems during the EM political incident. Notes were taken of conversations and more formal interviews. From this the technical and authority systems of the institution were described and compared. Results indicated that (1) the loose coupling of the technical and the authority systems made the EM political incident possible; (2) employees were more tightly coupled on organizational goals and more loosely coupled on organizational means; (3) political activists did not make full use of the EM's political medium potential; and (4) when the college district's administration refused to limit anyone's use of the EM network, they reinforced the integrity of both the authority and the technical systems.
Implications included: (1) the potential of some of the research methods for EM study, especially fantasy theme analysis; (2) a political interpretation of EM language, especially flaming; (3) the importance of technical and rhetorical skills for mature EM users; and (4) the role of the authority and technical systems in the debate about appropriate EM network use within an organization. 相似文献
Client/server, open systems, joint application development, and legacy systems—what happens when the silver bullet meets the glass house? And what does all of this have to do with end-user computing, anyway? Read this column and find out. 相似文献
The coevolution of genomics and proteomics has led to advancements in the field of diagnosis and molecular mechanisms of disease. Proteomics is now stepping into the field of obstetrics, where early diagnosis of pregnancy complication such as preeclampsia (PE) is imperative. PE is a multifactorial disease characterized by hypertension with proteinuria, which is a leading cause of maternal and neonatal morbidity and mortality occurring in 5-7% of pregnancies worldwide. This review discusses the probable molecular mechanisms that lead to PE and summarizes the proteomics research carried out in understanding the pathogenicity of PE, and for identifying the candidate biomarker for diagnosis of the disease. 相似文献
We present a number of alternative ways of handling transitive binary relations that commonly occur in first-order problems, in particular equivalence relations, total orders, and transitive relations in general. We show how such relations can be discovered syntactically in an input theory, and how they can be expressed in alternative ways. We experimentally evaluate different such ways on problems from the TPTP, using resolution-based reasoning tools as well as instance-based tools. Our conclusions are that (1) it is beneficial to consider different treatments of binary relations as a user, and that (2) reasoning tools could benefit from using a preprocessor or even built-in support for certain types of binary relations.
Fish oils containing different levels of polymers of triacylglycerols formed during autoxidation were incubated with pancreatic
lipase to establish whether these polymers are substrates for lipase hydrolysis. With oils containing low amounts (less than
4%) of triacylglycerol polymers as substrates, both triacylglycerols and polymers of triacylglycerols were almost completely
hydrolyzed, and fatty acid monomers and monoacylglycerols were the major lipid products. Under the same incubation conditions,
some triacylglycerols remained intact when highly oxidized oils containing 20 or 30% triacylglycerol polymers were the substrate.
The fatty acid composition of these residual triacylglycerols was almost identical to that of triacylglycerols present at
the start of the assay. When fish oil containing 30% triacylglycerol polymers was incubated with the lipase, the component
triacylglycerols and polymers of triacylglycerols were hydrolyzed at similar rates, and fatty acid dimers were detected as
a product. It is concluded that the high molecular weight polymers of triacylglycerols present in oxidized fish oils can be
hydrolyzed by pancreatic lipasein vitro. 相似文献