Determination of the bulk-saturated liquid condition for maximum heat fluxes at boiling crises

In this paper is presented a method of predicting the thermodynamic state of the bulk-saturated liquid at which peak nucleate boiling and minimum film boiling heat fluxes attain a maximum in pool boiling. The data in the form of saturated pressure and temperature in both absolute and reduced quantities are listed for several cryogenic liquids, hydrocarbons and halocarbon refrigerants. It is observed that the bulk liquid condition for a maximum in critical heat flux in nucleate boiling corresponds to intermolecular separation at maximum attractive potential, which in turn can be determined from saturated liquid density data. The predictions are fairly well corroborated by experimental data available in literature.     

XPS and XAES studies on hydrogen storage magnesium-based alloys

XPS and XAES studies of air-exposed Mg₂Cu and Mg₂Ni alloys showed surface decomposition and preferential segregation of Mg by the influence of oxygen and moisture. The segregated magnesium is mostly present as oxide and hydroxide on the surface. The second metallic component namely Ni or Cu is also present in the oxidized state. The passivation of these alloys arises by the oxidation of the transition metal component. We suggest that the activation of these alloys involves reduction of the oxidized 3d elements and the formation of metallic clusters.     

Experimental investigation on a series–parallel cluster of photovoltaic panels

This paper presents results of experimental investigations on a field of 8 photovoltaic panels assembled 2 in series and 4 such parallel combinations. The diurnal and environmental effects have been characterized systematically. The usage conditions are clean and dusty states of panels, the centers of each series combinations shorted and unshorted. It is observed that the curvature at the maximum power point of the I–V curve could be an indicator of the panel characteristics. The temperature effects on the voltage at the maximum power point are also discussed. It is brought out that field evaluation is essential and often maximum power point tracking can be dispensed if a known load exists and a judicious choice of battery bank capacity is made.     

High optical quality InP-based nanopillars fabricated by a top-down approach

Dense and uniform arrays of InP-based nanopillars were fabricated by dry etching using self-assembly of colloidal silica particles for masking. The pillars, both single and arrays, fabricated from epitaxially grown InP and InP/GaInAsP/InP quantum well structures show excellent photoluminescence (PL) even at room temperature. The measured PL line widths are comparable to the as-grown wafer indicating high quality fabricated pillars. A stamping technique enables transfer with arbitrary densities of the nanopillars freed from the substrate by selectively etching a sacrificial InGaAs layer.     

Optomechanical transduction of an integrated silicon cantilever probe using a microdisk resonator

Sensitive transduction of the motion of a microscale cantilever is central to many applications in mass, force, magnetic resonance, and displacement sensing. Reducing cantilever size to nanoscale dimensions can improve the bandwidth and sensitivity of techniques like atomic force microscopy, but current optical transduction methods suffer when the cantilever is small compared to the achievable spot size. Here, we demonstrate sensitive optical transduction in a monolithic cavity-optomechanical system in which a subpicogram silicon cantilever with a sharp probe tip is separated from a microdisk optical resonator by a nanoscale gap. High quality factor (Q ≈ 10(5)) microdisk optical modes transduce the cantilever's megahertz frequency thermally driven vibrations with a displacement sensitivity of ≈4.4 × 10(-16) m/(Hz)(1/2) and bandwidth >1 GHz, and a dynamic range >10(6) is estimated for a 1 s measurement. Optically induced stiffening due to the strong optomechanical interaction is observed, and engineering of probe dynamics through cantilever design and electrostatic actuation is illustrated.     

Hydrothermal synthesis and electrochemical properties of Li₃V₂(PO₄)₃/C-based composites for lithium-ion batteries

To improve performance at higher rates, we developed a hydrothermal method to prepare carbon-coated monoclinic lithium vanadium phosphate (Li(3)V(2)(PO(4))(3)) powder to be used as a cathode material for Li-ion batteries. The structural, morphological and electrochemical properties were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and galvanostatic charge-discharge cycling. A superior cycle and rate behavior are demonstrated for Li(3)V(1.85)Sc(0.15)(PO(4))(3)/C and Li(2.96)Ca(0.02)V(2)(PO(4))(3)/C electrodes at charge-discharge current rates above 5C.     

Evaluation of decision fusion strategies for effective collaboration among heterogeneous fault diagnostic methods

Numerous methodologies for fault detection and identification (FDI) in chemical processes have been proposed in literature. However, it is extremely difficult to design a perfect FDI method to efficiently monitor an industrial-scale process. In this work, we seek to overcome this difficulty by using multiple heterogeneous FDI methods and fusing their results so that the strengths of the individual FDI methods are combined and their shortcomings overcome. Several decision fusion strategies can be used for this purpose. In this paper, we study the relative benefits of utility-based and evidence-based decision fusion strategies. Our results from a lab-scale distillation column and the popular Tennessee Eastman challenge problem show that in situations where no single FDI method offers adequate performance, evidence-based fusion strategies such as weighted voting, Bayesian, and Dempster-Shafer based fusion can provide (i) complete fault coverage, (ii) more than 40% increase in overall fault recognition rate, (iii) significant improvement in monitoring performance, and (iv) reduction in fault detection and diagnosis delays.     

Sequential methodology for integrated optimization of energy and water use during batch process scheduling

Though commonly encountered in practice, energy and water minimization simultaneously during batch process scheduling has been largely neglected in literature. In this paper, we present a novel framework for incorporating simultaneous energy and water minimization in batch process scheduling. The overall problem is decomposed into three parts - scheduling, heat integration, and water reuse optimization - and solved sequentially. Our approach is based on the precept that in any production plant, utilities (energy and water) consumption is subordinate to the production target. Hence, batch scheduling is solved first to meet an economic objective function. Next, alternate schedules are generated through a stochastic search-based integer cut procedure. For each resulting schedule, minimum energy and water reuse targets are established and networks identified. As illustrated using two well-known case studies, a key feature of this approach is its ability to handle problems that are too complex to be solved using simultaneous methods.     

镍-磷-硫酸钡化学复合镀层的研制

在由硫酸镍31g/L、次磷酸钠22g/L、乙醇酸30g/L、乙酸钠13g/L、二甲胺0.8g/L、全氟乙基碘化铵0.1g/L及重晶石(即硫酸钡)0～25g/L组成的稳定镀液中,采用化学镀的方法在低碳钢上制备了Ni-P-BaSO4复合镀层.其表面形貌采用扫描电镜进行分析,耐蚀性以动电位极化及电化学阻抗谱测试.镍-磷合金基...