546 research outputs found
Power Bus Isolation Using Power Islands in Printed Circuit Boards
Power islands are often employed in printed circuit board (PCB) designs to alleviate the problem of power bus noise coupling between circuits. Good isolation can be obtained over a wide frequency band due to the large series impedance provided by the gap between the power islands. However, power bus resonances may degrade the isolation at high frequencies. The amount of isolation also depends on the type of connection between power islands and the components on the board. This paper experimentally investigates the effectiveness of several power island structures up to 3.0 GH
Designing Power Bus Decoupling for CMOS Devices
The adequacy of the DC power bus decoupling for CMOS devices can be determined if the effective board decoupling capacitance, the CMOS load capacitance, the CMOS power dissipation capacitance, the switching time, and the allowable bus noise voltage are known. A simple method is presented for estimating the effective decoupling capacitance. The load and power dissipation capacitance values are shown analytically and experimentally to be closely related to the transient current. The transient current and switching time are used to estimate the transient noise voltage on the power bu
A Solar-Hydrogen Energy Conversion Scheme for Agricultural Use
A solar energy activated system is presented which can produce hydrogen and hydrogen-derived fuels (methanol) for use on farms. The device, named solar-kine , also can produce fertilizer (anhydrous ammonia) as a byproduct of the hydrogen. A cost analysis shows that solar-kine may be mass-producible and sold to farmers for between 14,700. This is equivalent to giving the fanner energy at a price of 3.66 per million BTU\u27s (in 1974 dollars). Presently (Spring, 1974) regular gasoline used in tractors at 43¢ per gallon, represents a cost to the farmer of $3.77 per million BTU\u27s. As oil-based fuels increase in price in the next few years, solar-kine may represent a reasonable alternative to keep food prices down.
The solar-kine system uses concentrated solar energy which can be converted into a high-density electric current by means of a thermionic heat engine. The rejected heat and electric current from the thermionic converter is supplied to an electrolysis cell which, in turn, produces hydrogen and oxygen gas. Chemical process equipment will use the hydrogen and oxygen to produce a methanol (CH3OH) fuel supply for internal combustion engines used on farm machines. The hydrogen can also be used to manufacture ammonia, ammonium nitrate (NH4NO3), and ammonium sulfate [(NH4)2SO4)] fertilizers. The following materials can be produced which are useful to the farmer: a) hydrogen gas, b) oxygen gas, c) liquid tractor fuel, d) fertilizer, e) ammonia, f) electricity, and e) heat energy
We feel that any unconventional energy system, such as solar-kine, must interface and serve the conventional use of fuel energy if it is to have lasting merits. This is why we feel that it is desirable to have the complete conversion of solar energy into a liquid fuel that is safe to handle and store, and which also can be used in any conventional fossil-fuel burning system with minimum modifications.
Solar energy is compatible with our environment; it is free, and its supply cannot be exhausted. It is also available at any geographic location without requiring transportation to the user\u27s site (See Fig. 2). Its major advantage over fossil fuel comes from the fact that it does not add any net heat content to the earth [5,6].
A small on-site energy system is best for the farmer because,
a) It can be mass produced at 106 or more, units per year,b) Power levels needed by farms are low, 100-500 KW, c)Farm energy is used over a large geographical area, d)The main source of energy (the sun) is everywhere available,e) Heat rejected from the heat engine (thermionic) is used in other portions of the system to increase overall efficiency, and may be used in part to heat buildings,f) The farmer would be energy-independent from the price and supply undulations of the industrial complex,g) Legal considerations which regulate the large energy distribution systems would not apply, or affect, the proposed system as used by the farmer,h) Last, and possibly most important, the farmer would have a dependable fuel supply at the lowest possible cost. In the future, the proposed system will supply energy at a cost much lower than petroleum-derived energy
Algal food and fuel coproduction can mitigate greenhouse gas emissions while improving land and water-use efficiency
The goals of ensuring energy, water, food, and climate security can often conflict.Microalgae (algae) are
being pursued as a feedstockfor both food and fuels—primarily due to algae’s high areal yield and ability
to grow on non-arable land, thus avoiding common bioenergy-food tradeoffs. However, algal cultivation
requires significant energy inputs that may limit potential emission reductions.We examine the tradeoffs
associated with producing fuel andfood from algae at the energy–food–water–climate nexus.We use the
GCAM integrated assessment model to demonstrate that algalfood production can promote reductions
in land-use change emissions through the offset of conventional agriculture. However,fuel production,
either via co-production of algal food and fuel or complete biomass conversion to fuel, is necessary to
ensure long-term emission reductions, due to the high energy costs of cultivation. Cultivation of salt–
water algae for food products may lead to substantial freshwater savings; but, nutrients for algae
cultivation will need to be sourced from waste streams to ensure sustainability. By reducing the land
demand of food production, while simultaneously enhancingfood and energy security, algae can further
enable the development of terrestrial bioenergy technologies including those utilizing carbon capture and
storage. Our results demonstrate that large-scale algae research and commercialization efforts should
focus on developing both food and energy products to achieve environmental goals.https://iopscience.iop.org/article/10.1088/1748-9326/11/11/114006/metaPublished versio
Influence of long-term tillage and rotation combinations on crop yields and selected soil parameters: I. Results obtained for a Mollic Ochraqualf soil
PIN97 Treatment Patterns and Characteristics of Medicare Beneficiaries with Hiv Related Cachexia
Improving the High-Frequency Attenuation of Shunt Capacitor, Low-Pass Filters
Circuit board mounted, shunt capacitive filters are less effective at high frequencies because of the mutual inductance (M) that exists between the input and output ports. An approximate expression for the mutual inductance is M=(μh/2π)ln(h/a); where h=via length and a=radius of the via connecting the capacitor to the return plane. The reduced mutual inductance associated with the new, three-terminal, surface-mounted capacitor results in more than 15 dB increased attenuation compared to two-terminal capacitors over the 0.3-6.0 GHz range with 50 Ω source and load termination
Considerations for Magnetic-Field Coupling Resulting in Radiated EMI
Parasitic inductance in printed circuit board geometries can worsen the EMI performance and signal integrity of high-speed digital designs. Partial-inductance theory is a powerful tool for analyzing inductance issues in signal integrity. However, partial inductances may not adequately model magnetic flux coupling to EMI antennas because the EMI antennas are typically open loops. Therefore, partial inductances may not always accurately predict radiated EMI from noise sources, unless used in a full-wave analysis such as PEEC. Partial inductances can be used, however, to estimate branch inductances, which can be used to predict EMI. This paper presents a method for decomposing loop or self inductances into branch inductances. Experimental as well as analytical investigations are used to compare branch- and partial-inductances
Influence of long-term tillage and rotation combinations on crop yields and selected soil parameters: II. Results obtained for a Typic Fragiudalf soil
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