An embedded 0.8 V/480 /spl mu/W 6b/22 MHz flash ADC in 0.13-/spl mu/m digital CMOS process using a nonlinear double interpolation technique

For high-data-rate wireless communication, low-voltage baseband converters integrated with DSP in deep submicrometer processes are area- and power-efficient. Through careful architecture selections and circuit techniques, this paper demonstrates a low-voltage (0.8 V), low-power (480 /spl mu/W), 6-b/22-MHz flash-interpolation ADC which occupies 0.3 mm/sup 2/ and achieves 33 dB SNDR and 47 dB SFDR. The power efficiency of this converter is 0.6 pJ/conv-step which compares favorably with all published results. We also introduce a nonlinear double interpolation technique that enables the use of a 0.13-/spl mu/m standard digital CMOS process without special resistors.     

二氧化碳管道意外泄漏减压过程的断裂控制研究进展

管道是二氧化碳捕集、利用和封存（carbon capture, utilization, and storage,CCUS）技术产业链中输运大量二氧化碳（CO₂）的最优方式,但其在运行中具有意外泄漏风险。本文从实验和计算机模拟两个方面综述了国内外开展CO₂管道泄漏减压、断裂扩展的研究进展,分析了相态、管材、埋地条件等初始状态对裂纹扩展规律的影响。阐述了状态方程、杂质因素、理论模型对开展实验和模拟计算研究的影响。归纳了适用于建立减压波预测模型的状态方程,开展流固耦合研究的理论方法和模拟仿真软件,设计CO₂输运管道参考的技术文档。总结了当前CO₂管道泄漏减压、断裂扩展控制研究方面需深入研究的科学问题,展望了亟待开展的研究内容,包括构建多元混合物状态方程在三相点、相间线的计算模型;探究裂纹裂间处CO₂热物性质与裂纹断裂扩展的耦合关系;建立管道止裂准则,开发、优化CO₂输运管道专用止裂器。     

Coating of Small Alumina Crucibles with Magnesia using a Two-Step Drain Casting Technique

A new technique of coating ceramic ware using two-step drain casting is described in which small alumina crucibles are drain cast followed by drain casting a magnesia coat in the same mold. Cosintering at 1500°C resulted in ware defects unless heating schedules embodying arrests at lower temperatures were used.     

Volume of fluid method for interfacial reactive mass transfer: Application to stable liquid film

A volume of fluid method is developed in order to simulate reactive mass transfer in two-phase flows and is applied to study reactive laminar liquid film. The thermodynamic equilibrium of chemical species at the interface is considered using Henry's law. The chemical species concentration equation is solved using primitive variables and local fluxes are locally directly calculated at the interface. The present treatment of jump discontinuity of chemical concentration is consistent with a volume of fluid approach and the difficulty to calculate accurate local mass flux across interface is overcome. For plane interface, the precision of the numerical simulation is found to be very satisfactory while for curved interface a special procedure has been developed to reduce the development of spurious fluxes at the interface. The algorithm is validated for different cases by comparison with available solutions. The method is then applied to study non-reactive and reactive mass transfer in a falling liquid film. The results show that the liquid side mass transfer is well predicted by the Higbie (1935) theory when the transfer is controlled by the film advection provided that adequate parameters are considered, i.e. the actual velocity at interface and not the average liquid film velocity. For situations controlled by diffusion, the Sherwood number tends to a constant value characteristic of purely diffusive situations. For the reactive mass transfer, first and second order irreversible chemical reactions in the liquid phase are considered. The numerical results are compared respectively, with Danckwerts (1970) and Brian et al. (1961) solutions and good agreement is observed. The proposed Volume of Fluid method is shown to be well adapted to deal with interfacial reactive mass transfer problems.     

Synthesis of calcium hydroxyapatite from calcium carbonate and different orthophosphate sources: A comparative study

The synthesis of calcium hydroxyapatite (Ca-HA) starting from calcium carbonate and different orthophosphate sources, including orthophosphoric acid, potassium, sodium and ammonium dihydrogen orthophosphates, was investigated under ambient conditions. The reaction started with calcium carbonate dissolution in an acid medium, followed by rapid precipitation of calcium cations with orthophosphate species to form calcium phosphate based particles which were in the size range of 0.4–1 μm. These particles then agglomerated into much larger ones, up to 350 μm in diameter (aggregates). These aggregates possessed an unstable porous structure which was responsible for the porosity of the final products. The highest specific surface area and pore volume were obtained with potassium dihydrogen orthophosphate. On the other hand, orthophosphoric acid led to the highest dissolution of calcium carbonate and the complete precipitation of orthophosphate species. Under ambient conditions, calcium phosphate based solid products of low crystallinity were formed. Different intermediates were identified and a reaction pathway proposed.     

Articulate Virtual Labs in Thermodynamics Education: A Multiple Case Study*

This paper describes the use of CyclePad—an articulate virtual laboratory for creating and analyzing thermodynamics cycles—at three different types of educational institutions: a research university, an engineering technology program in a large state university, and a military academy. Case studies of each site were created based on classroom observations, student surveys, and interviews with faculty. In comparing these three institutions, we found that the context of the school and the ways in which professors chose to implement CyclePad led to different student experiences. Depending on the types of problems that students worked on, they found the software more or less helpful in increasing their understanding of thermodynamics. Students in the class that had the most constraints on its curriculum, where little change was possible, were less able to take full advantage of the software's capabilities.     

Behavior of Cyclically Loaded Squat Reinforced Concrete Bridge Columns Upgraded with Advanced Composite-Material Jackets

This paper summarizes comprehensive experimental studies on scaled models of squat bridge columns repaired and retrofitted with advanced composite-material jackets. In the experimental program, a total of 14 half-scale squat circular and rectangular reinforced concrete columns were tested under fully reversed cyclic shear in a double bending configuration. In order to provide a basis for comparison, a total of three as-built columns were tested. Another 10 column samples were tested after being retrofitted with different composite jacket systems. One circular as-built column was repaired after failure. The repair process involved both crack injection as well as addition of carbon/epoxy composite jacket. The repaired column was then retested and evaluated. Experimental results showed that all as-built columns developed an unstable behavior and failed in brittle shear mode. The common failure mode for all retrofitted samples was due to flexure with significant improvement in the column ductility. The repaired column demonstrated ductility enhancement over the as-built sample.     

Reduced and selective integration techniques in the finite element analysis of plates

Efforts to develop effective plate bending finite elements by reduced integration techniques are described. The basis for the development is a ‘thick’ plate theory in which transverse shear strains are accounted for. The variables in the theory are all kinematic, namely, displacements and independent rotations. As only C⁰ continuity is required, isoparametric elements may be employed, which result in several advantages over thin plate elements. It is shown that the avoidance of shear ‘locking’ may be facilitated by reduced integration techniques. Both uniform and selective schemes are considered. Conditions under which selective schemes are invariant are identified, and they are found to have an advantage over uniform schemes in the present situation. It is pointed out that the present elements are not subject to the difficulties encountered by thin plate theory elements, concerning boundary conditions. For example, the polygonal approximation of curved, simply-supported edges is convergent. Other topics discussed are the equivalence with mixed methods, rank deficiency, convergence criteria and useful mass ‘lumping’ schemes for dynamics. Numerical results for several thin plate problems indicate the high degree of accuracy attainable by the present elements.     

FIR digital filters with simultaneous conditions on amplitude and delay

A general analytic technique is given for the design of FIR digital filters with simultaneous conditions on both the amplitude and delay responses. It is shown that phase linearity can be maintained only within the passband, resulting in increased amplitude selectivity as compared with filters with exact linear phase at all frequencies.     

Investigation of Removal of Cu(II) Ions by Commercial Activated Carbon: Equilibrium and Thermodynamic Studies

Protection of Metals and Physical Chemistry of Surfaces - The present study deals with the application of activated carbon for the adsorptive removal of Cu(II) from its aqueous solutions. This...