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ZERO EMISSION COAL POWER, A NEW CONCEPT
The Zero Emission Coal Alliance (ZECA) is developing an integrated zero emission process that generates clean energy carriers (electricity or hydrogen) from coal. The process exothermically gasifies coal using hydrogen to produce a methane rich intermediate state. The methane is subsequently reformed using water and a CaO based sorbent. The sorbent supplies the energy needed to drive the reforming reaction and simultaneously removes the generated CO{sub 2} by producing CaCO{sub 3}. The resulting hydrogen product stream is split, approximately 1/2 going to gasify the next unit of coal, and the other half being the product. This product stream could then be split a second time, part being cleaned up with a high temperature hydrogen separation membrane to produce pure hydrogen, and the remainder used to generate electricity via a solid oxide fuel cell (SOFC). The inevitable high temperature waste heat produced by the SOFC would in turn be used to regenerate the CaO by calcining the CaCO{sub 3} product of the reforming stage thereby generating a pure stream of CO{sub 2}. The CO{sub 2} will be dealt with a mineral sequestration process discussed in other papers presented at this conference. The SOFC has the added advantage of doubling as an …
Date:
April 1, 2001
Creator:
ZIOCK, H. -J.; LACKNER, K. S. & HARRISON, D. P.
Object Type:
Article
System:
The UNT Digital Library
Zero Energy Buildings: A Critical Look at the Definition; Preprint
A net zero-energy building (ZEB) is a residential or commercial building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies. Despite the excitement over the phrase ''zero energy'', we lack a common definition, or even a common understanding, of what it means. In this paper, we use a sample of current generation low-energy buildings to explore the concept of zero energy: what it means, why a clear and measurable definition is needed, and how we have progressed toward the ZEB goal.
Date:
June 1, 2006
Creator:
Torcellini, P.; Pless, S.; Deru, M. & Crawley, D.
Object Type:
Article
System:
The UNT Digital Library
A zero-power radio receiver.
This report describes both a general methodology and some specific examples of passive radio receivers. A passive radio receiver uses no direct electrical power but makes sole use of the power available in the radio spectrum. These radio receivers are suitable as low data-rate receivers or passive alerting devices for standard, high power radio receivers. Some zero-power radio architectures exhibit significant improvements in range with the addition of very low power amplifiers or signal processing electronics. These ultra-low power radios are also discussed and compared to the purely zero-power approaches.
Date:
September 1, 2004
Creator:
Brocato, Robert Wesley
Object Type:
Report
System:
The UNT Digital Library
Zero-Release Mixed Waste Process Facility Design and Testing
A zero-release offgas cleaning system for mixed-waste thermal treatment processes has been evaluated through experimental scoping tests and process modeling. The principles can possibly be adapted to a fluidized-bed calcination or stream reforming process, a waste melter, a rotarykiln process, and possibly other waste treatment thermal processes. The basic concept of a zero-release offgas cleaning system is to recycle the bulk of the offgas stream to the thermal treatment process. A slip stream is taken off the offgas recycle to separate and purge benign constituents that may build up in the gas, such as water vapor, argon, nitrogen, and CO2. Contaminants are separated from the slip stream and returned to the thermal unit for eventual destruction or incorporation into the waste immobilization media. In the current study, a standard packed-bed scrubber, followed by gas separation membranes, is proposed for removal of contaminants from the offgas recycle slipstream. The scrub solution is continuously regenerated by cooling and precipitating sulfate, nitrate, and other salts that reach a solubility limit in the scrub solution. Mercury is also separated by the scrubber. A miscible chemical oxidizing agent was shown to effectively oxidize mercury and also NO, thus increasing their removal efficiency. The current study …
Date:
February 1, 2004
Creator:
Boardman, Richard D.; Deldebbio, John A.; Kirkham, Robert J.; Clemens, Martin K.; Geosits, Robert & Wan, Ping
Object Type:
Article
System:
The UNT Digital Library
Zeste maintains repression of Ubx transgenes: Support for a new model of polycomb repression
During late embryogenesis, the expression domains of homeotic genes are maintained by two groups of ubiquitously expressed regulators: the Polycomb repressors and the Trithorax activators. It is not known how the activities of the two maintenance systems are initially targeted to the correct genes. Zeste and GAGA are sequence specific DNA binding proteins previously shown to be Trithorax group activators of the homeotic gene Ultrabithorax (Ubx). Here we demonstrate that Zeste and GAGA DNA binding sites at the proximal promoter are also required to maintain, but not to initiate, repression of Ubx. Further, the repression mediated by Zeste DNA binding site is abolished in zeste null embryos. These data imply that Zeste and probably GAGA mediate Polycomb repression. We present a model in which the dual transcriptional activities of Zeste and GAGA are an essential component of the mechanism that chooses which maintenance system is to be targeted to a given promoter.
Date:
September 1, 2001
Creator:
Hur, Man-Wook; Laney, Jeffrey D.; Jeon, Sang-Hack; Ali, Janann & Biggin, Mark D.
Object Type:
Article
System:
The UNT Digital Library
ZFITTER: A Semi-analytical program for fermion pair production in e+ e- annihilation, from version 6.21 to version 6.42
ZFITTER is a Fortran program for the calculation of fermion pair production and radiative corrections at high energy e{sup +}e{sup -} colliders; it is also suitable for other applications where electroweak radiative corrections appear. ZFITTER is based on a semi-analytical approach to the calculation of radiative corrections in the Standard Model. They present a summary of new features of the ZFITTER program version 6.42 compared to version 6.21. The most important additions are: (1) some higher-order QED corrections to fermion pair production, (2) electroweak one-loop corrections to atomic parity violation, (3) electroweak one-loop corrections to {bar {nu}}{sub e}{nu}{sub e} production, (4) electroweak two-loop corrections to the W boson mass and the effective weak mixing angle.
Date:
July 1, 2005
Creator:
Arbuzov, A. B.; Awramik, M.; Czakon, M.; Freitas, A.; Grunewald, M. W.; Monig, K. et al.
Object Type:
Article
System:
The UNT Digital Library
Zgoubi-ing AGS : spin motion with snakes and jump-quads, Gγ = 43.5 through Gγ = 46.5 and beyond
This Note reports on the first, and successful, simulations of particle and spin dynamics in the AGS in presence of the two helical snakes and of the tune-jump quadrupoles, using the ray-tracing code Zgoubi. It includes DA tracking in the absence or in the presence of the two helical snakes, simulation of particle and spin motion in the snakes using their magnetic field maps, spin flipping at integer resonances in the 36+Qy depolarizing resonance region, with and without tune-jump quadrupole gymnastics. It also includes details on the setting-up of Zgoubi input data files and on the various numerical methods of concern in and available from Zgoubi.
Date:
October 1, 2009
Creator:
Meot, F.; Ahrens, L.; Glenn, J.; Huang, H.; Luccio, A.; MacKay, W. W. et al.
Object Type:
Report
System:
The UNT Digital Library
ZioLib: A parallel I/O library
In a distributed memory parallel environment, many applications rely on a serial I/O strategy, where the global array is gathered on a single MPI process and then written out to a file. I/O performance with this approach is largely limited by single process I/O bandwidth. Even when parallel I/O is used, satisfactory parallel scaling is not always observed. It is because in many applications fields are not necessarily in a most favorable parallel decomposition for I/O. The best I/O rates are obtained when a field is decomposed with respect to the array's last dimension (referred to here as Z). Another situation often encountered in many applications is that a field in CPU resident memory is in one index order but must be stored in a disk file in another order. Changing index orders can complicate a parallel I/O implementation and slow down I/O. ZioLib facilitates an efficient parallel I/O for arrays in such situations. In case of a write, ZioLib remaps a distributed field into a Z-decomposition on a subset of processes (which will be called the I/O staging processes) and from there writes to a disk file in parallel. In this Z-decomposition, the data layout of the remapped array …
Date:
August 1, 2003
Creator:
Yang, Woo-Sun & Ding, Chris
Object Type:
Report
System:
The UNT Digital Library
Zion National Park Visitor Center: Performance of a Low-Energy Building in a Hot, Dry Climate: Preprint
Zion National Park in Utah has experienced substantial growth in the number of visitors to the park, leading to a negative impact on visitor experience and the surrounding environment. To reduce environmental impact and improve visitor experience, National Park Service (NPS) staff planned the development of a new Visitor Center Complex. Saving and protecting natural resources is core to the mission of the Park and minimizing energy resource use is considered part of the natural resource. NPS staff worked with NREL to integrate energy efficiency into the design of the new Visitor Center.
Date:
July 1, 2004
Creator:
Torcellini, P.; Pless, S.; Long, N. & Judkoff, R.
Object Type:
Article
System:
The UNT Digital Library
Zion National Park Visitor Center: Significant Energy Savings Achieved through a Whole-Building Design Process: Preprint
The National Park Service (NPS) applied a whole-building design process developed at the National Renewable Energy Laboratory (NREL) to create a building that performs more than 70% better than a comparable code-compliant building at no additional construction cost. This whole-building design process involves a committed design team, including the energy consultant, in the earliest conceptual design phase and continues through building commissioning. The design team for this project included the architect, engineer, energy consultant, landscape architect, owner, operator, and others who could influence the building design and operation. Extensive whole-building energy and lighting computer simulations were conducted throughout the process, which included the integration of energy efficient and renewable energy technologies into the building. The design team, inspired by natural cooling within the canyon, developed simple solutions to create an extremely energy efficient building. The se strategies included natural ventilation cooling, cooltowers for evaporative cooling without distribution fans, daylighting, massive building materials, Trombe walls and direct solar gains for heating, engineered window overhangs for solar load control, a building automation system to maintain comfort and control the energy-efficient lighting system, and a roof-mounted photovoltaic system to offset building electrical loads and ensure a power supply during the frequent utility grid …
Date:
July 1, 2002
Creator:
Torcellini, P.; Judkoff, R. & Hayter, S.
Object Type:
Article
System:
The UNT Digital Library
Zip Codes and Maps Digital Database via Zip-Codes.com
Zip Codes and Maps Digital Database via Zip-Codes.com. Includes Examples and pictures of the website.
Date:
August 1, 2005
Creator:
United States. Department of Defense.
Object Type:
Text
System:
The UNT Digital Library
Zip Codes and Maps Digital Database via Zip-Codes.com
Zip Codes and Maps Digital Database via Zip-Codes.com.EX:Zip code 98315 Silverdale Washington WA.
Date:
August 1, 2005
Creator:
United States. Department of Defense.
Object Type:
Text
System:
The UNT Digital Library
Zirconia-Based Mixed Potential CO/HC Sensors with LaMnO3 and Th-doped YSZ Electrodes
Abstract: We have investigated the performance of dual metal oxide electrode mixed potential sensors in an engine-out, dynamometer environment. Sensors were fabricated by sputtering thin films of LaMnO{sub 3} and Tb-doped YSZ onto YSZ electrolyte. Au gauze held onto the metal oxide thin films with Au ink was used for current collection. The exhaust gas from a 4.8L, V8 engine operated in open loop, steady-state mode around stoichiometry at 1500 RPM and 50 Nm. The sensor showed a stable EMF response (with no hysteresis) to varying concentrations of total exhaust gas HC content. The sensor response was measured at 620 and 670 C and shows temperature behavior characteristic of mixed potential-type sensors. The results of these engine-dynamometer tests are encouraging; however, the limitations associated with Au current collection present the biggest impediment to automotive use.
Date:
October 1, 2000
Creator:
Brosha, Eric L.; Mukundan, Rangachary; Brown, David R.; Garzon, Fernando H.; Visser, J. H.; Thompson, David J. et al.
Object Type:
Article
System:
The UNT Digital Library
Zirconium Oxide Nanostructures Prepared by Anodic Oxidation
Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to …
Date:
January 1, 2008
Creator:
Dang, Y. Y.; Bhuiyan, M.S. & Paranthaman, M. P.
Object Type:
Article
System:
The UNT Digital Library
Zn-Site Determination in Protein Encapsulated ZnxFe3-xO4 Nanoparticles
The X-ray absorption spectra of the Fe and Zn L-edges for 6.7 nm Fe{sub 3}O{sub 4} nanoparticles grown inside 12 nm ferritin protein cages with 10%, 15%, 20% and 33% zinc doping, shows that the Zn is substitutional as Zn{sup 2+} within the iron oxide host structure. A Neel-Arrhenius plot of the blocking temperature in the frequency dependent ac-susceptibility measurements show that the particles are non-interacting and that the anisotropy energy barrier is reduced with Zn loading. X-ray magnetic circular dichroism (XMCD) of the Fe displays a linear decrease with Zn-doping in sharp contrast to the initial increase present in the bulk system. The most plausible explanation for the moment decrease is that Zn substitutes preferentially into the tetrahedral A-site as a Zn{sup 2+} cation, generating a mixed spinel.
Date:
October 1, 2008
Creator:
Pool, V. L.; Klem, M. T.; Holroyd, J.; Harris, T.; Arenholz, E.; Young, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Zn speciation in a soil contaminated by the deposition of a dredged sediment by synchrotron X-ray techniques
The nature and proportion of Zn species present in an agricultural soil overlaid by a dredged contaminated sediment have been untangled by the novel combination of three non-invasive synchrotron-based x-ray techniques: x-ray microfluorescence ({mu}SXRF), microdiffraction ({mu}XRD), and absorption spectroscopy (EXAFS). One primary (franklinite) and two secondary (phyllomanganate and phyllosilicate) Zn-containing minerals were identified in the initial soil, and another primary (ZnS) and a new secondary (Fe-(oxyhydr)oxide) Zn species in the covered soil. The quantitative analysis of EXAFS spectra recorded on bulk samples indicated that ZnS and Zn-Fe (oxyhydr)oxides amounted to 71+-10 percent and 27+-10 percent, respectively, and the other Zn species to less than 10 percent. The two new Zn species found in the covered soil result from the gravitational migration of ZnS particles initially present in the sediment, and from their further oxidative dissolution and fixation of leached Zn on F e (oxyhydr) oxides.
Date:
September 1, 2003
Creator:
Isaure, Marie-Pierre; Manceau, Alain; Laboudigue, Agnes; Tamura, Nobumichi & Marcus, Matthew A.
Object Type:
Article
System:
The UNT Digital Library
ZnO:Al Doping Level and Hydrogen Growth Ambient Effects on CIGS Solar Cell Performance
None
Date:
May 1, 2008
Creator:
Duenow, J. N.; Gessert, T. A.; Wood, D. M.; Egaas, B.; Noufi, R. & Coutts, T. J.
Object Type:
Presentation
System:
The UNT Digital Library
ZnO:Al Doping Level and Hydrogen Growth Ambient Effects on CIGS Solar Cell Performance: Preprint
Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) cells require a highly conducting and transparent electrode for optimum device performance. ZnO:Al films grown from targets containing 2.0 wt.% Al2O3 are commonly used for this purpose. Maximum carrier mobilities of these films grown at room temperature are ~20-25 cm2V-1s-1. Therefore, relatively high carrier concentrations are required to achieve the desired conductivity, which leads to free carrier absorption in the near infrared (IR). Lightly doped films (0.05 - 0.2 wt.% Al2O3), which show less IR absorption, reach mobility values greater than 50 cm2V-1s-1 when deposited in H2 partial pressure. We incorporate these lightly doped ZnO:Al layers into CIGS PV cells produced at the National Renewable Energy Laboratory (NREL). Preliminary results show quantum efficiency values of these cells rival those of a past world-record cell produced at NREL that used 2.0 wt.% Al-doped ZnO films. The highest cell efficiency obtained in this trial was 18.1%.
Date:
May 1, 2008
Creator:
Duenow, J. N.; Gessert, T. A.; Wood, D. M.; Egaas, B.; Noufi, R. & Coutts,T. J.
Object Type:
Article
System:
The UNT Digital Library
ZnTe:Cu Contact Optimization Strategies for Single-Junction and Multijunction CdS/CdTe PV Device Designs
The ability to produce high-performance CdS/CdTe photovoltaic (PV) devices that incorporate high-transparency back contacts for multijunction thin-film PV applications will require an even greater level of understanding than has been required for single-junction devices. This study reports some of our initial investigations at NREL to modify the ZnTe:Cu contact process previously developed for single-junction applications for optimal use as a transparent back contact. We have succeeded in producing devices incorporating a transparent ZnTe:Cu/ITO/metal-grid contact that demonstrates nominally identical light I-V (LIV) performance to the ZnTe:Cu/Ti contact used in single-junction devices. However, we have determined that the transparent conducting oxide (TCO), CdS, CdTe, and ZnTe:Cu layers are all factors in the optical absorption within the device. Finally, we have concluded that optimizing the transparent ZnTe:Cu contact for use with NREL-produced device material will require a more detailed understanding of the evolution of the junction region during the contact process.
Date:
May 1, 2003
Creator:
Gessert, T.; Coutts, T.; Dhere, R.; Duda, A. & Levi, D.
Object Type:
Article
System:
The UNT Digital Library
Zoning for Distributed Wind Power - Breaking Down Barriers: Preprint
Zoning regulations for the use of small wind turbines vary from state to state and from one local jurisdiction to the next. This paper examines the zoning experiences of small wind turbine owners, options for local actions, and examples of state and federal limited preemption of local zoning authority as a means of promoting the implementation of new technologies.
Date:
August 1, 2005
Creator:
Green, J. & Sagrillo, M.
Object Type:
Article
System:
The UNT Digital Library
The ZOOM minimization package
A new object-oriented Minimization package is available for distribution in the same manner as CLHEP. This package, designed for use in HEP applications, has all the capabilities of Minuit, but is a re-write from scratch, adhering to modern C++ design principles. A primary goal of this package is extensibility in several directions, so that its capabilities can be kept fresh with as little maintenance effort as possible. This package is distinguished by the priority that was assigned to C++ design issues, and the focus on producing an extensible system that will resist becoming obsolete.
Date:
November 1, 2004
Creator:
Fischler, Mark S. & Sachs, D.
Object Type:
Article
System:
The UNT Digital Library
ZPR-6 Assembly 7 High {Sup 240} Pu Core : A Cylindrical Assemby With Mixed (Pu, U)-Oxide Fuel and a Central High {Sup 240} Pu Zone.
Over a period of 30 years more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited to form the basis for criticality safety benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactor physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more complex nature, a small number of assemblies from the other two classes would make useful criticality safety benchmarks because they have …
Date:
October 1, 2007
Creator:
Lell, R. M.; Schaefer, R. W.; McKnight, R. D.; Tsiboulia, A.; Rozhikhin, Y.; Division, Nuclear Engineering et al.
Object Type:
Report
System:
The UNT Digital Library
Zr and Mo isotopic constraints on the origins of unusual types of presolar SiC grains.
Although most presolar silicon carbide grains form in asymptotic giant branch red giant stars (the so-called mainstream grains) or supernovae (the X-grains), there are a number of other minor types of grains whose origin is less clear. The dominant mechanisms of heavy element nucleosynthesis, the s-process and r-process, are thought to occur mainly in AGB stars and supernovae, respectively [1], and the isotopic patterns in heavy elements in presolar grains can be used to constrain their origins. We have previously reported that mainstream SiC grains have strong enrichments in the s-process isotopes of Sr, Zr and Mo [2-5] and that X-grains have an unusual Mo isotopic composition that differs from s- and r-process expectations [6,7]. We report here the first measurements of Zr and Mo isotopes in several grains of other rare types that were found in the same mount as the mainstream and X-grains reported previously.
Date:
March 1, 2000
Creator:
Pellin, M. J.; Davis, A. M.; Calaway, W. F.; Lewis, R. S.; Clayton, R. N. & Amari, S.
Object Type:
Article
System:
The UNT Digital Library
ZZ ---> l+ l- v anti-v production in p anti-p collisions at s**(1/2) = 1.96-TeV
None
Date:
August 1, 2008
Creator:
Abazov, V. M.; /Dubna, JINR; Abbott, B.; U., /Oklahoma; Abolins, M.; U., /Michigan State et al.
Object Type:
Article
System:
The UNT Digital Library