ABSTRACT: : We report that porous silicon acoustic Bragg reflectors and AlN-based transducers can be successfully combined and processed in a commercial solidly mounted resonator production line. The resulting device takes advantage of the unique acoustic properties of porous silicon in order to form a monolithically integrated bulk acoustic wave resonator. 相似文献
Ceramic Matrix Composites (CMCs) are increasingly demanded especially for the production of structural components for several industries such as aerospace because of their excellent thermo-mechanical and fatigue properties. As one of the last production steps final machining is necessary to meet the required tolerances. From the economic point of view final machining of CMCs is highly critical and special knowledge is assumed to avoid irreparable damage, because of their heterogeneous, anisotropic and brittle nature. In this work diamond grinding and diamond milling have been applied to a 2D C/C-SiC composite at various feed rates and cutting speeds and in both main laminate directions, in-plane and out-of-plane. The microstructures of in-plane and out-of-plane machining indicate different material removal mechanisms due to different composite architecture. Increasing feed rate leads generally to more surface defects and consequently to higher roughness. Little influence on the four-point-bending strength was observed when changing the machining speed. 相似文献
Water pollution regulations and the types and sources of water pollution common to a ``typical' cement plant are discussed. With the exception of the problem of totally dissolved solids in ``process' water, solutions to most of the other water pollution problems common to a cement plant have been known. A solution to the problem of totally dissolved solids in ``process' water is offered in this paper. 相似文献
4,4′-Di(N-carbazoyl)biphenyl monomer (CBP) was synthesized and coated onto ITO–glass surface by electrochemical oxidative polymerization. Its CV shows two distinct one-electron and stepwise oxidation processes occurred at 1.29 and 1.61 V. By using this property, the monomer was electrochemically polymerized separately at these oxidation states and thus, two different oligomer films were obtained afterwards. Their spectro-electrochemical and electrochromic properties were also investigated. Switching ability of the oligomers was evaluated by kinetic studies upon measuring the percent transmittance (%T) at their maximum contrast point, indicating that these oligomers were found to be suitable material for electrochromic devices. 相似文献
In the online and printed versions of the original article, there was a typographical error in I. Peker’s name. His name is
spelled correctly above. This error occurred in both the html and pdf versions of the online article.
The online version of the original article can be found at 相似文献
The influence of bond–coating on the mechanical properties of plasma-spray coatings of hydroxyatite on Ti was investigated.
Plasma-spray powder was produced from human teeth enamel and dentine. Before processing the main apatite coating, a very thin
layer of Al2O3/TiO2 was applied on super clean and roughened, by Al2O3 blasting, Ti surface as bond-coating. The experimental results showed that bond-coating caused significant increase of the
mechanical properties of the coating layer: In the case of the enamel powder from 6.66 MPa of the simple coating to 9.71 MPa
for the bond-coating and in the case of the dentine powder from 6.27 MPa to 7.84 MPa, respectively. Both tooth derived powders
feature high thermal stability likely due to their relatively high content of fluorine. Therefore, F-rich apatites, such those
investigated in this study, emerge themselves as superior candidate materials for calcium phosphate coatings of producing
medical devices. The methods of apatite powder production and shaping optimization of powder particles are both key factors
of a successful coating. The methods used in this study can be adopted as handy, inexpensive and reliable ways to produce
high quality of powders for plasma spray purposes.
An erratum to this article is available at . 相似文献
This paper considers the scheduling problems arising in two- and three-machine manufacturing cells configured in a flowshop
which repeatedly produces one type of product and where transportation of the parts between the machines is performed by a
robot. The cycle time of the cell is affected by the robot move sequence as well as the processing times of the parts on the
machines. For highly flexible CNC machines, the processing times can be changed by altering the machining conditions at the
expense of increasing the manufacturing cost. As a result, we try to find the robot move sequence as well as the processing
times of the parts on each machine that not only minimize the cycle time but, for the first time in robotic cell scheduling
literature, also minimize the manufacturing cost. For each 1-unit cycle in two- and three-machine cells, we determine the
efficient set of processing time vectors such that no other processing time vector gives both a smaller cycle time and a smaller
cost value. We also compare these cycles with each other to determine the sufficient conditions under which each of the cycles
dominates the rest. Finally, we show how different assumptions on cost structures affect the results. 相似文献
A statistical database (SDB) is a database that provides simple summary statistics (e.g., SUM, COUNT, MAX, MEDIAN, etc.) about individuals in the database and that supports statistical data analysis. When SDB users infer protected information in the SDB from responses to queries, we say that the SDB is compromised.
Summary tables are tabular representations of summary data. For a given aggregate function and a set of attributes to specify subsets of individuals in the SDB, all possible summary tables form a lattice. The SDB security problem in the lattice model is defined as preventing the users from obtaining the information that a table element (i.e., cell) is of size one.
In this paper, to solve the SDB security problem in the lattice model, we generalize three cell-level control techniques, namely, cell suppression by merging, m-cube, axis merging, into the lattice model. We define the concept of information loss, derive various properties of the minimum information loss, and then investigate the effectiveness of heuristic algorithms for the minimum information loss in each of the three cell-level control techniques. 相似文献