570 research outputs found
Application of Market Models to Network Equilibrium Problems
We present a general two-side market model with divisible commodities and
price functions of participants. A general existence result on unbounded sets
is obtained from its variational inequality re-formulation. We describe an
extension of the network flow equilibrium problem with elastic demands and a
new equilibrium type model for resource allocation problems in wireless
communication networks, which appear to be particular cases of the general
market model. This enables us to obtain new existence results for these models
as some adjustments of that for the market model. Under certain additional
conditions the general market model can be reduced to a decomposable
optimization problem where the goal function is the sum of two functions and
one of them is convex separable, whereas the feasible set is the corresponding
Cartesian product. We discuss some versions of the partial linearization
method, which can be applied to these network equilibrium problems.Comment: 18 pages, 3 table
Governance structure and Operating Performance of Japanese Major Banks
近年,銀行の経営破綻が相次ぎ,金融システムの不安定性が高まっている。そのため,銀行のガバナンス構造を明らかにし,銀行経営の効率性を高めることは喫緊の課題である。ところで,非金融企業と異なり預金という特殊な負債を保有する銀行の場合,株主によるガバナンスが重要である。本稿では, 1990年から1998年をサンプル期間として,日本の大手銀行18行のパネル・データを用いて,株式所有構造の変化,株式所有構造と経営効率性および労働分配率との関係を分析した。その結果,①銀行の株式所有構造は経営効率性を重視する株主の保有比率が上昇する傾向にあること,②銀行経営に対して株主は経営効率性を高める方向で影響を与えていること,③株式保有比率が高いほど労働分配率が低下すること,すなわち株主への分配が多くなる傾向があること,の3点が明らかになった。従って,少なくとも1990年代において,銀行のガバナンス構造は株主への利益分配を重視する「新古典派型企業」としての性格を示していると言える
A Short Counterexample Property for Safety and Liveness Verification of Fault-tolerant Distributed Algorithms
Distributed algorithms have many mission-critical applications ranging from
embedded systems and replicated databases to cloud computing. Due to
asynchronous communication, process faults, or network failures, these
algorithms are difficult to design and verify. Many algorithms achieve fault
tolerance by using threshold guards that, for instance, ensure that a process
waits until it has received an acknowledgment from a majority of its peers.
Consequently, domain-specific languages for fault-tolerant distributed systems
offer language support for threshold guards.
We introduce an automated method for model checking of safety and liveness of
threshold-guarded distributed algorithms in systems where the number of
processes and the fraction of faulty processes are parameters. Our method is
based on a short counterexample property: if a distributed algorithm violates a
temporal specification (in a fragment of LTL), then there is a counterexample
whose length is bounded and independent of the parameters. We prove this
property by (i) characterizing executions depending on the structure of the
temporal formula, and (ii) using commutativity of transitions to accelerate and
shorten executions. We extended the ByMC toolset (Byzantine Model Checker) with
our technique, and verified liveness and safety of 10 prominent fault-tolerant
distributed algorithms, most of which were out of reach for existing
techniques.Comment: 16 pages, 11 pages appendi
Reactant Jetting in Unstable Detonation
We note the common existence of a supersonic jet structure locally embedded within a surrounding transonic flow field in the hitherto unrelated phenomena of unstable gaseous
detonation and hypervelocity blunt body shock wave interaction. Extending prior results that demonstrate the consequences of reduced endothermic reaction rate for the supersonic jet fluid in the blunt body case, we provide an explanation for observations of locally reduced OH PLIF signal in images of the keystone reaction zone structure of weakly unstable detonations. Modeling these flow features as exothermically reacting jets with similarly reduced reaction rates, we demonstrate a mechanism for jetting of bulk pockets of unreacted fluid with potentially differing kinetic pathways into the region behind the primary detonation front of strongly unstable mixtures. We examine the impact of mono-atomic and diatomic diluents on transverse structure. The results yield insight into the mechanisms of transition and characteristic features of both weakly and strongly unstable mixtures
The effect of magnetic and electric fields on the processes of food freezing
The article summarizes the results of studies based on scientific publications on the effect of magnetic fields (MF) and electric fields (EF) on the kinetics of freezing processes applied onto biological tissue and on their properties. The processes of freezing food media on installations equipped with the Cells Alive System (CAS) magnetic system manufactured by ABI Co., Ltd., Japan are considered in this article. It is shown that the majority of researchers did not confirm the benefits claimed by the CAS system developers in comparison with the processes of fast freezing in the chambers without the magnetic field. In the case of using the alternating magnetic fields (AMF) with high field induction values, the effect is more pronounced. The application of strong static or alternating EF contributes to the creation of a fine-grained structure of ice, reduces the freezing duration and decreases mass loss during the food thawing
Implementation of Fault-tolerant Quantum Logic Gates via Optimal Control
The implementation of fault-tolerant quantum gates on encoded logic qubits is
considered. It is shown that transversal implementation of logic gates based on
simple geometric control ideas is problematic for realistic physical systems
suffering from imperfections such as qubit inhomogeneity or uncontrollable
interactions between qubits. However, this problem can be overcome by
formulating the task as an optimal control problem and designing efficient
algorithms to solve it. In particular, we can find solutions that implement all
of the elementary logic gates in a fixed amount of time with limited control
resources for the five-qubit stabilizer code. Most importantly, logic gates
that are extremely difficult to implement using conventional techniques even
for ideal systems, such as the T-gate for the five-qubit stabilizer code, do
not appear to pose a problem for optimal control.Comment: 18 pages, ioptex, many figure
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