An Experimental Investigation into the Feed Rate Capacity of Rotary Valve and Blow Tank Feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.     

THE FEDERAL ROLE IN ENERGY R&D

This paper documents and analyzes recent trends in Federal energy research and development programs. In light of the marketplace philosophy of the present Administration, the possible benefits of a strong Federal research program versus the potential advantages of relying on private sector research programs to develop new technology alternatives are analyzed in some detail. The impacts of the Reagan budget cuts and other initiatives on several major energy programs, including nuclear power, photovoltaics, and conservation, are also analyzed. This analysis reveals some of the difficulties inherent in attempting to project the consequences of particular policy decisions in a complex and changing environment, and identifies some of the problems of trying to evaluate the success of particular programs or actions on a limited time scale.     

DuD Recht

DuD Recht

DuD Recht     

Interplay Between Wetting and Phase Behavior in Binary Polymer Films and Wedges: Monte Carlo Simulations and Mean Field Calculations

Confining a binary mixture, one can profoundly alter its miscibility behavior. The qualitative features of miscibility in confined geometry are ratheruniversal and shared by polymer mixtures as well as small molecules, but the unmixing transition in the bulk and the wetting transition are typically well separated in polymer blends. The interplay between wetting and miscibility of a symmetric polymer mixture via large-scale Monte Carlo simulations in the framework of the bond fluctuation model and via numerical self–consistent field calculations is studied. The film surfaces interact with the monomers via short ranged potentials, and the wetting transition of the semi–infinite system is of first order. It can be accurately located in the simulations by measuring the surface and interface tensions and using Young’s equation. If both surfaces in a film attract the same component, capillary condensation occurs and the critical point is close to the critical point of the bulk. If surfaces attract different components, an interface localization/delocalization occurs which gives rise to phase diagrams with two critical points in the vicinity of the pre-wetting critical point of the semi–infinite system. The crossover between these two types of phase diagrams as a function of the surface field asymmetry is studied. The dependence of the phase diagram on the film thickness Δ for antisymmetric surface fields is investigated. Upon decreasing the film thickness, the two critical points approach the symmetry axis of the phase diagram, and below a certain thickness Δ_tri, there remains only a single critical point at the symmetric composition. This corresponds to a second-order interface localization/delocalization transition even though the wetting transition is of first order. At a specific film thickness, Δ_tri, tricritical behavior is found. The behavior of antisymmetric films is compared with the phase behavior in an antisymmetric double wedge. While the former is the analog of the wetting transition of a planar surface, the latter is related to the filling behavior of a single wedge. Evidence for a second-order interface localization/delocalization transition in an antisymmetric double wedge is presented, and its unconventional critical behavior is related to the predictions of Parry et al. (Phys. Rev. Lett. 83:5535 (1999)) for wedge filling. The critical behavior differs from the Ising universality class and is characterized by strong anisotropic fluctuations.Invited paper presented at the Fifteenth Symposium on Thermophysical Properties, June 022–27, 2003, Boulder, Colorado, U.S.A.     

Nanorod heterostructures showing photoinduced charge separation

Size- and shape-dependent property modifications of semiconductor nanocrystals have been a subject of intense interest because of their potential for future engineering devices. The bandgap and related optical-property tuning of these materials are mainly governed by the nature of their band edges. In addition, fusing one type of nanocrystal over another enables further control of material properties that are dependent on the relative alignments of their energy levels. On a molecular scale, the synthesis of supramolecular compounds has inspired advances in theories for photoinduced charge transfer. Heterostructured nanocrystals potentially provide a nanoscale analog of such systems. A method for preparing heterostructured nanocrystals of complex morphologies showing photoinduced charge separation is presented. It is shown that the energy and lifetime of the charge-transfer photoluminescence band can be tuned by changing the relative alignment of band edges in CdSe/CdTe heterostructure nanorods. The long-lived charge transfer states in these type II semiconductors may make them attractive for photovoltaic applications.     

Calibrating whole building energy models: An evidence-based methodology

This paper reviews existing case studies and methods for calibrating whole building energy models to measured data. This research describes a systematic, evidence-based methodology for the calibration of these models. Under this methodology, parameter values in the final calibrated model reference the source of information used to make changes to the initial model. Thus, the final model is based solely on evidence. Version control software stores a complete record of the calibration process, and the evidence on which the final model is based. Future users can review the changes made throughout the calibration process along with the supporting evidence. In addition to the evidence-based methodology, this paper also describes a new zoning process that represents the real building more closely than the typical core and four perimeter zone approach. Though the methodology is intended to apply to detailed calibration studies with high resolution measured data, the primary aspects of the methodology (evidence-based approach, version control, and zone-typing) are independent of the available measured data.     

Integration of Low-Impact Development into the International Stormwater BMP Database

Low impact development (LID) strategies are being encouraged in many communities as an approach to reduce potential adverse impacts of development on receiving streams. Many questions exist regarding how well various LID strategies perform in different settings, just as similar questions have been raised regarding performance of traditional stormwater best management practices (BMPs). Whereas historical focus on BMP performance has been water quality concentrations or loads, characterization of volume reduction benefits for both conventional and LID practices is increasingly an objective of researchers and stormwater managers. More than a decade ago, Urban Water Resources Research Council (UWRRC) members worked to develop a set of standardized monitoring and reporting protocols for traditional BMPs and to establish a master database for the purpose of evaluating BMP performance and the factors affecting performance. This effort culminated in the International Stormwater BMP Database (www.bmpdatabase.org), which contains data for more than 360 BMPs and continues to operate as a clearinghouse for stormwater BMP data and performance analyses. During 2008–2009, the International Stormwater BMP Database project expanded to better integrate LID into the database and develop a set of metrics that can be used to characterize BMP performance with regard to surface runoff volume reduction. This paper provides a condensed overview and progress report on the LID-focused effort, including the following topics: (1)?monitoring guidance for LID at the overall site development level, (2)?an overview of recent changes to the International Stormwater BMP Database to better accommodate LID studies, (3)?a summary of LID studies currently included in the database, and (4)?a proposed approach for evaluating performance of LID studies with regard to reducing surface runoff volumes.     

Emergent Properties of the BT SDH Network

When planning an SDH network, explicit structure, such as rings or a network hierarchy, is often imposed to allow for easier network protection and management. Decisions on node connectivity are also heavily dependent on available transmission capacity and network geography, as well as the demands placed on the SDH transport layer. The strictly imposed structure therefore makes it unlikely for unplanned properties to appear but here we describe how the BT SDH network exhibits emergent power-law properties in a range of metrics. These properties are similar to those previously found in the Internet, but the Internet in contrast is not globally planned, has adaptive elements such as dynamic routing and peering agreements, lacks explicit imposed structure, and is less coupled to transmission topologies.This paper shows that even with a wide range of restrictions and controls the BT SDH network topology follows power-laws and we offer possible sources for them, concentrating on the possible effect of adjacent network layers. The existence of these properties has wide implications in network modelling, as well as network scaling, growth, and robustness analysis.