828 research outputs found
Flexible superconducting ceramic polymer composites and method of making same, U.S. Patent 5,108,981
No full textSuperconducting ceramic material is woven into an interconnected structure and embedded in a polymer to produce a flexible, superconducting ceramic material. The polymer also provides protection from moisture. The ceramic polymer composite is fabricated by soaking a carbon fabric in a solution of metal nitrates, ethylene glycol and citric acid to yield a nominal composition of, for example, YBa2Cu3O7-x. Heat treatment results in the decomposition of the nitrates, organics and carbon fabric to produce an interconnected structure of the superconducting ceramic material which takes the shape of the original carbon fabric on a reduced scale. In addition, the processing conditions yield significant grain orientation. The superconducting grains of the ceramic material align along the direction of the original fabric weave which provides an improvement of the critical current densities
Perforated PZT polymer composites, U.S. Patent 4,422,003
No full textComposites of lead zirconate titanate (PZT) and inactive polymers with 3-1 and 3-2 patterns and a method of fabrication thereof are described. Fabrication is accomplished by drilling holes in sintered PZT blocks and filling the holes with epoxy or some other inactive polymer. The influence of hole size and volume fraction PZT on the hydrostatic properties of the composite is evaluated. By decoupling the piezoelectric coefficients d33 and d21 in the composite, the hydrostatic coefficients are greatly enhanced
Windows Vista inside out / Ed Bott, Carl Siechert, Craig Stinson.
No full textIncludes index.Electronic reproduction. Boston, Mass. : Safari Books Online 2006. Mode of access: World Wide Web. Available to subscribing institutions. s2006 maun s.xxviii,1101 pages
Methods for producing novel ceramic composites, U.S. Patent 6,004,500
No full textA process for making ceramic composites includes the steps of: a) forming a polymer composition into a three-dimensional mold; b) filling said three-dimensional mold with one or more ceramic containing compositions; c) heating said filled mold to dry and sinter the ceramic; d) removing at least a portion of said three-dimensional mold thereby forming voids; and e) filling the voids with a second composition which has a piezoelectric coefficient which is substantially different from the piezoelectric coefficient of said ceramic structure. Steps a through e yield a controlled, non-random piezoelectric ceramic composite having 2-3, 3-2 or 3--3 connectivity with respect to the sintered ceramic and the second composition throughout the composite
Increasing the reliability and the profit in a redundancy allocation problem
No full textThis paper proposes a new mathematical model for multi-objective redundancy allocation problem (RAP) without component mixing in each subsystem when the redundancy strategy can be chosen for individual subsystems. Majority of the mathematical model for the multi-objective redundancy allocation problems (MORAP) assume that the redundancy strategy for each subsystem is predetermined and fixed. In general, active redundancy has received more attention in the past. However, in practice both active and cold-standby redundancies may be used within a particular system design and the choice of the redundancy strategy becomes an additional decision variable. The proposed model for MORAP simultaneously maximizes the reliability and the net profit of the system. And finally, to clarify the proposed mathematical model a numerical example will be solved. Keywords: Redundancy Allocation Problem, Serial-Parallel System, Redundancy Strategies, MORAP
Development a policy for the production of Bitcoins with renewable energy sources
No full textBitcoin, the first decentralized digital currency introduced by an anonymous person or group since 2008, has attracted worldwide attention. A significant number of economists have introduced Bitcoin as a new phenomenon in the 21st century that could reduce global inflation. Given the tens of thousands of digital currencies that have emerged since the advent of Bitcoin and its price growth trend over more than a decade, which are signs of the growth of this business. In addition to being money, Bitcoin has always been considered a tool for investing and storing value, which is why it is called digital gold.One of the most important problems in the production or extraction of Bitcoins is the high-powerconsumption by miners. If the energy sources of electricity generation are supplied by non-renewable energy sources, in addition to emitting air pollutant gases, it will increase greenhouse gases and consequently contribute to climate change.In this research, based on the idea of the authors, which is that the economic support of Bitcoin is energy, a strategy for producing Bitcoin from renewable energy sources is considered. First, the amount of electrical energy consumption by Bitcoin production is calculated based on statistical data, and then based on the price of electricity in different countries of the world and its global average, the base price of Bitcoin is calculated.In the following, four scenarios are proposed for the production of Bitcoin by electricity supplied from non-renewable energy sources. These scenarios include coal-fired steam power plants, natural gas-fired power plants, natural gas/oil gas-fired power plants, and dual-cycle (steam and gas cycles) natural gas-fired power plants. Based on the amount of electricity required to produce one Bitcoin, the amount of pollutants emitted to produce Bitcoin and its social costs are calculated. These costs should be added to the base cost of Bitcoin production ifnon-renewable energy sources are used to produce Bitcoin.Then, renewable energy sources for Bitcoin production based on the price of electricity generated by renewable energy sources are examined.Based on the analyses, how to choose the best renewable energy source to produce Bitcoin is presented as a scenario.This article briefly answers two key questions: 1. At what price of Bitcoin is it cost-effective for governments to produce it? 2. What is the best renewable energy source to produce it? These two questions can be useful in creating a roadmap and strategy for economists and governments.Future EnergyOpen Access Journalhttps://doi.org/10.55670/fpll.fuen.3.2.2May2024| Volume 03| Issue 02| Pages 16-23Journal homepage: https://fupubco.com/fuenISSN 2832-032
Noise Measurements of a Low-Noise Amplifier in the FDM Readout System for SAFARI
No full textThe SPICA-SAFARI instrument requires extremely sensitive transition edge sensor (TES) arrays with a noise equivalent power of 2×10-19W/Hz and a readout system with an output noise that is dominated by the detector noise. It is essential to ensure the frequency domain multiplexing (FDM) readout system in SAFARI meets the noise requirement. The FDM system in SAFARI consists essentially of LC filters, a superconducting quantum interference device, a room-temperature low-noise amplifier (LNA), and a demultiplexer. Here we present a noise study of the LNA from a laboratory amplifier chain. We found the equivalent current and voltage noise of the LNA to be 5.4pA/Hz and 315pV/Hz, respectively, which are low enough to read out SAFARI’s TES arrays.QN/Gao La
Sustainable Water management scheme for the Negin Safari Park
No full textThough the perils of climate change on our environment are common knowledge its mitigation through informed planning is widely absent. This research project aims to aid the architect in developing a design which has a comparatively lower ecological footprint and focuses on opportunistic utilization of renewable resources readily available in the context. Within the preview of this thesis the potential of developing a sustainable water management scheme for the Negin safari park located in the Fars province of Iran is studied.Iran is facing a situation of drought for the past few years which has had an adverse impact on the region. One of the communities to have been affected by this are the Qashqai nomads of Iran, who have been threatened with deprivation of their freedom due to the economic woes brought by drought. The Negin safari park being developed in the region aims to uplift this community and provide a platform for them to be able to share their work and culture. However, the influx of tourists due to the development of a Safari park further increases the stress on the depleting water resources in the region. In turn development of water technologies facilitating the reclamation of waste water, conservation of water and mitigation of extreme withdrawal of resources needs to be studied and implemented. In order to create a design which consciously uses the water resources and facilitates re-use of waste water, different water technologies have been identified and studied to understand its feasibility for installation in Iran. Once the ideal technologies were identified, a water management scheme was developed which facilitated water autarky in the park. Further on the relation of the built form with the technology was explored. The technologies which were shortlisted entailed requirements which had a direct impact on the design of the built form and its spatial organization. The final product of this thesis entails a customized set of design guidelines for the development of a Safari park in Iran. These guidelines have stemmed from the optimization strategy used in designing the Negin safari park with the intended water technologies. Adhering to the concept of developing the park as an eco-tourist destination attention has been placed to propose sustainable technologies with lower energy requirement and maintenance. It is believed that through implementation of these technologies the added stress on water demand caused by the erection of a Negin safari park in a drought hit region can be reduced. The implementation of these technologies can also further help in educating the local community and lead to encouragement of widespread implementation of these systems. This graduation project is an attempt to develop an informed relation between resource flows and spatial design in order to enable an uninterrupted functioning of the Safari park leading to prosperity of the region and its people. Architecture, Urbanism and Building Science
Performance of a low-noise test facility for the SAFARI TES bolometer arrays
No full textWe have constructed a test facility for characterizing the focal plane arrays of SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. SAFARI’s three bolometer arrays are populated with extremely sensitive (NEP ? 2 × 10?19 W/? Hz) transition edge sensors with a transition temperature close to 100 mK. The extreme sensitivity and low saturation power (?4 fW) of SAFARI’s detectors present challenges to characterizing them. In optimizing the SAFARI Detector System Test Facility we have paid careful attention to stray-light exclusion as well as electrical, magnetic, and mechanical isolation.We present measurements verifying the facility’s performance and analyze them in terms of a two-fluid model of the TES current on the transition to investigate the background power level. We have measured a detector NEP of (5.1 ± 0.4) × 10?19 WHz?1/2, showing that the facility is ready to test the SAFARI prototype arrays and is approaching the performance needed for testing the flight arrays.Kavli Institute of NanoScienceApplied Science
Evaluation of an Attachment–Detachment Kinetic Model for Flotation
No full textThis paper compares model predictions from a novel kinetic model with data from five fundamental single-mineral literature flotation datasets. The empirical correlations proposed by Safari and Deglon (2018) are modified to improve their robustness, requiring only a single best-fit regression coefficient per mineral type. Experimental and model-predicted rate constants were compared on a parity chart where a reasonable linear correlation was observed, with a gradient of 0.95 and an overall R2 value of 0.97. Thereafter experimental and model-predicted trends from the flotation datasets were compared for particle size, contact angle, agitation, and gas flow rate. Model-predicted trends were reasonably accurate for most of the flotation datasets, but under-predicted the rate constant for larger particles for the data of Pyke (2004). In general model predictions were reasonably accurate, which is considered quite good, as these were obtained by fitting a single parameter per mineral type to several large flotation datasets, totaling 330 rate constants
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