1,975,163 research outputs found
Supercritical Water Gasification: Practical Design Strategies and Operational Challenges for Lab-Scale, Continuous Flow Reactors
Optimizing an industrial-scale supercritical water gasification process
requires detailed knowledge of chemical reaction pathways, rates, and product
yields. Laboratory-scale reactors are employed to develop this knowledge base.
The rationale behind designs and component selection of continuous flow,
laboratory-scale supercritical water gasification reactors is analyzed. Some
design challenges have standard solutions, such as pressurization and
preheating, but issues with solid precipitation and feedstock pretreatment
still present open questions. Strategies for reactant mixing must be evaluated
on a system-by-system basis, depending on feedstock and experimental goals, as
mixing can affect product yields, char formation, and reaction pathways.
In-situ Raman spectroscopic monitoring of reaction chemistry promises to
further fundamental knowledge of gasification and decrease experimentation
time. High-temperature, high-pressure spectroscopy in supercritical water
conditions is performed, however, long-term operation flow cell operation is
challenging. Comparison of Raman spectra for decomposition of formic acid in
the supercritical region and cold section of the reactor demonstrates the
difficulty in performing quantitative spectroscopy in the hot zone. Future
designs and optimization of SCWG reactors should consider well-established
solutions for pressurization, heating, and process monitoring, and effective
strategies for mixing and solids handling for long-term reactor operation and
data collection
Motives for Innovation Co-operation? Evidence from the Canadian Survey of Innovation
In this paper we analyse the decision of firms in the Canadian manufacturing sector to co-operate on innovation projects. Our focus is on the motives behind this decision and the firm characteristics, both general and with respect to innovation activities, which influence the motives for innovation co-operation. Using data from the Canadian Survey of Innovation 2005 we find that the factors influencing the decision to co-operate in order to access external knowledge are very similar to those influencing cost-sharing motives. We also show that public funding leads firms to cooperate in order to access external knowledge and R&D. --Innovation Co-operation,Motives for Co-operation,Canadian Survey of Innovation
Adding control to arbitrary unknown quantum operations
While quantum computers promise significant advantages, the complexity of
quantum algorithms remains a major technological obstacle. We have developed
and demonstrated an architecture-independent technique that simplifies adding
control qubits to arbitrary quantum operations-a requirement in many quantum
algorithms, simulations and metrology. The technique is independent of how the
operation is done, does not require knowledge of what the operation is, and
largely separates the problems of how to implement a quantum operation in the
laboratory and how to add a control. We demonstrate an entanglement-based
version in a photonic system, realizing a range of different two-qubit gates
with high fidelity.Comment: 9 pages, 8 figure
An analysis of the equational properties of the well-founded fixed point
Well-founded fixed points have been used in several areas of knowledge
representation and reasoning and to give semantics to logic programs involving
negation. They are an important ingredient of approximation fixed point theory.
We study the logical properties of the (parametric) well-founded fixed point
operation. We show that the operation satisfies several, but not all of the
equational properties of fixed point operations described by the axioms of
iteration theories
Old institutions, new challenges: the agricultural knowledge system in Hungary
This paper explores and analyses the Hungarian institutional system for the creation and the transfer of knowledge in the fi eld
of agriculture and rural development. We consider the constitution and operation of the Agricultural Knowledge System (AKS)
in Hungary, focussing on the formally organised aspects, and suggest that both the structure and content of the knowledge
needed in the sector have signifi cantly changed during the past decades. These changes, especially in relation to the sustainability
of agriculture, pose signifi cant challenges to traditional AKS institutions, which often have failed to change in line with
the new requirements. Based on a literature review, interviews and a national stakeholder workshop, we offer an analysis of
Hungarian AKS institutions, their co-ordination, co-operation and communication with each other and with Hungarian rurality,
and of the arising issues and problems concerning the creation and the fl ow of knowledge needed for sustainable agriculture.
We also briefl y explore characteristics of emerging bottom-up structures, called LINSAS (learning and innovation networks for
sustainable agriculture), and explore the signifi cance of the fi ndings in this article for the study of AKS in Europe. This article
is based on preliminary results of the SOLINSA research project, supported by the European Union’s Seventh Framework
Programme
A knowledge-based system for the automatic chronopotentiometric elucidation of electrode reaction mechanisms
A knowledge-based system for the elucidation of electrode reaction mechanisms based on chronopotentiometric experiments is described. The system runs the diagnostic experiments and uses the results in the reasoning process. New mechanistic knowledge can be added directly to its knowledge base in the form of production rules. The system is fully modular and its domain- specific modules can easily be changed for application to other electrochemical techniques. Correct operation of the system is demonstrated with the familiar reduction mechanisms of cadmium (II), zinc (II), cystamine and cinnamaldehyde
Increasing the power of the verifier in Quantum Zero Knowledge
In quantum zero knowledge, the assumption was made that the verifier is only
using unitary operations. Under this assumption, many nice properties have been
shown about quantum zero knowledge, including the fact that Honest-Verifier
Quantum Statistical Zero Knowledge (HVQSZK) is equal to Cheating-Verifier
Quantum Statistical Zero Knowledge (QSZK) (see [Wat02,Wat06]).
In this paper, we study what happens when we allow an honest verifier to flip
some coins in addition to using unitary operations. Flipping a coin is a
non-unitary operation but doesn't seem at first to enhance the cheating
possibilities of the verifier since a classical honest verifier can flip coins.
In this setting, we show an unexpected result: any classical Interactive Proof
has an Honest-Verifier Quantum Statistical Zero Knowledge proof with coins.
Note that in the classical case, honest verifier SZK is no more powerful than
SZK and hence it is not believed to contain even NP. On the other hand, in the
case of cheating verifiers, we show that Quantum Statistical Zero Knowledge
where the verifier applies any non-unitary operation is equal to Quantum
Zero-Knowledge where the verifier uses only unitaries.
One can think of our results in two complementary ways. If we would like to
use the honest verifier model as a means to study the general model by taking
advantage of their equivalence, then it is imperative to use the unitary
definition without coins, since with the general one this equivalence is most
probably not true. On the other hand, if we would like to use quantum zero
knowledge protocols in a cryptographic scenario where the honest-but-curious
model is sufficient, then adding the unitary constraint severely decreases the
power of quantum zero knowledge protocols.Comment: 17 pages, 0 figures, to appear in FSTTCS'0
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