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1.
《Informatik - Forschung und Entwicklung》2006,21(1-2):21-27
A promising application of future quantum computers is the simulation of physical systems of
a quantum nature. It has been estimated that a quantum computer operating with as few as 50–100
logical qubits would be capable of obtaining simulation results that are inaccessible to classical computers.
This chapter explains the basic principles of simulation on a quantum computer and reviews some applications. 相似文献
2.
Eike Jessen Dieter Michel Hans-Jürgen Siegert und Heinz Voigt 《Informatik - Forschung und Entwicklung》2008,22(4):217-225
Zusammenfassung AEG-Telefunken entwickelte seit 1957 Rechner. Neben den Prozessrechnern spielten die Gro?rechner
TR 4 und TR 440 eine wichtige Rolle. Von 1969 bis 1976 wurden 46 TR 440 installiert, bei einem Gesamtumsatz
von 730 Mio. DM (370 Mio. Euro) [2]. In der Produktpolitik spielten die Rechner keine zentrale Rolle,
obwohl eine ausgezeichnete technologische Ausgangsposition bestanden hatte und die Telefunkenrechner sp?ter
nachdrückliche technologiepolitische Unterstützung erhielten. Die Entwicklung des Systems TR
440 hatte mit wesentlichen konzeptionellen und technologischen Schwierigkeiten zu k?mpfen, wozu der
Mangel an qualifizierten Zulieferern und erfahrenen Mitabeitern kam. Trotzdem gelang es, bis 1970 den bislang
schnellsten in Europa entwickelten Rechner [6] fertig zu stellen und Systemsoftware zu entwickeln [9],
die den Produkten der Mitbewerber um Jahre voraus war. Von Anfang an hatte das Unternehmen nach geeigneten
Kooperationspartnern gesucht. Mit dem Verkauf des Gro?rechnergesch?ftes an Siemens gingen die
bereits laufenden Planungen für einen TR 440-Nachfolger zu Ende.
AEG-Telefunken developed computers since 1957. Besides process control computers, the large scale computers, TR 4 and TR 440, played an important role. 46 TR 440 computers were installed from 1969 to 1976, summing up to a sales volume of 730 Mio. DM (370 Mio. Euro) [2]. AEG-Telefunken did not consider computers as a strategic part of its product policy, though the company had had an excellent technological position for this business and the Telefunken computers got vigorous political support. The development of the TR 440 system had to defeat essential conceptual and technological difficulties, besides lack of qualified suppliers and experienced personnel. Nevertheless, the company could, by 1970, develop the fastest European computer so far [6], with system software ahead of competitors by years [9]. From the beginning, the company had been looking for business partners. With the sale of the large scale computer business to Siemens, all activities on a TR 440 successor were stopped. AEG-Telefunken computer business strategy is also subject of a paper to appear in the IEEE Annals of the History of Computing.相似文献
3.
Martin R?tteler 《Informatik - Forschung und Entwicklung》2006,55(3):3-20
Quantum algorithms are a field of growing interest within the theoretical computer science as
well as the physics community. Surprisingly, although the number of researchers working on the subject
is ever-increasing, the number of quantum algorithms found so far is quite small. In fact, the task of
designing new quantum algorithms has been proven to be extremely difficult. In this paper we give an overview
of the known quantum algorithms and briefly describe the underlying ideas. Roughly, the algorithms presented
are divided into hidden subgroup type algorithms and in amplitude amplification type algorithms. While
the former deal with problems of group-theoretical nature and have the promise to yield strong separations
of classical and quantum algorithms, the latter have been proved to be a prolific source of algorithms
in which a polynomial speed-up as compared to classical algorithms can be achieved. We also discuss
quantum algorithms which do not fall under these two categories and give a survey of techniques of
general interest in quantum computing such as adiabatic computing, lower bounds for quantum algorithms,
and quantum interactive proofs. 相似文献
4.
Dominik Janzing 《Informatik - Forschung und Entwicklung》2006,8(4):83-90
Progress in controlling quantum systems is the major pre-requisite
for the realization of quantum computing, yet the results of quantum computing research can also be useful
in solving quantum control problems that are not related to computational problems. We arguethat quantum
computing provides clear concepts and simple models for discussing quantum theoretical problems. In this
article we describe examples from completely different fields where models of quantum computing and quantum
communication shed light on quantum theory.
First we address quantum limits of classical low power computation and argue that the terms of quantum
information theory allows us to discuss device-independent bounds. We
argue that a classical bit behaves to some extent like a quantum bit in the time period where
it switches its logical value. This implies that a readout during the switching process generates
entropy. A related problem is the distribution of timing information like clock signals in low power
devices. For low signal energy, the situation is close to phase-covariant cloning problems in quantum information
theory. 相似文献
5.
6.
J?rn Müller-Quade 《Informatik - Forschung und Entwicklung》2006,11(2):39-54
This chapter describes the applicability of quantum cryptography beyond key exchange. The section
is devided into two parts: one describing applications of quantum cryptography different from key exchange
and the other considering countermeasures to additional threats like coercibility or traffic analysis.
Every section ends with a short summary or an appraisal in boldface and in the conclusions all
topics of this section are briefly outlined and in an outlook we give a personal statement about the
relevance of quantum cryptographic pro tocols and promising future directions of research. 相似文献
7.
Alexander Wolff 《Informatik - Forschung und Entwicklung》2007,42(4):23-44
This paper deals with automating the drawing of subway maps. There are two features of schematic
subway maps that make them different from drawings of other networks such as flow charts or organigrams.
First, most schematic subway maps use not only horizontal and vertical lines, but also diagonals. This
gives more flexibility in the layout process, but it also makes the problem provably hard. Second, a subway
map represents a network whose components have geographic locations that are roughly known to the users
of such a map. This knowledge must be respected during the search for a clear layout of the network.
For the sake of visual clarity the underlying geography may be distorted, but it must not be given up, otherwise
map users will be hopelessly confused.
In this paper we first give a rather generally accepted list of rules that should be adhered
to by a good subway map. Next we survey three recent methods for drawing subway maps, analyze their
performance with respect to the above rules, and compare the resulting maps among each other and to official
subway maps drawn by graphic designers. We then focus on one of the methods, which is based on mixed-integer
linear programming, a widely-used global optimization technique. This method guarantees to find a drawing
that fulfills a subset of the above-mentioned rules (if such a drawing exists) and optimizes a weighted
sum of costs that correspond to the remaining rules. The method can draw even large subway networks such
as the London Underground in an aesthetically pleasing manner, similar to maps made by professional graphic
designers. If station labels are included in the optimization process, so far only medium-size networks
can be drawn. Finally we give evidence why drawing good subway maps is difficult (even without labels). 相似文献
8.
Eike Jessen Dieter Michel und Heinz Voigt 《Informatik - Forschung und Entwicklung》2008,22(4):227-235
Zusammenfassung Der Telefunkenrechner TR 440 war bei seiner Fertigstellung 1970 die schnellste bisher in Europa entwickelte
und produzierte Maschine. 46 Maschinen wurden in Wissenschaftseinrichtungen, bei Beh?rden und in der
Industrie installiert. Der TR 440 folgte dem 1962 fertig gestellten TR 4, der auf demselben Markt durch
Leistungsf?higkeit und sein innovatives Compilerkonzept eine wichtige Stellung erobert hatte. Der
TR 440 wurde als Maschine für den Teilnehmerbetrieb entwickelt. Die Maschine war einer der ersten
gro?en Rechner mit integrierten Schaltungen. Sie verfügte über Seitenadressierung und ein
ausgefeiltes System von privilegierten Funktionen. Die Leistung des Prozessors betrug knapp 1 Mips, die
Hauptspeicherkapazit?t 1.5 MB. Ausgangspunkt, Struktur und Technologie werden aus heutiger Sicht
beschrieben. Ein Nachfolgeprodukt, TR 550, wurde konzipiert, aber nicht mehr entwickelt. Die Wertsch?tzung
des TR 440 bei den Nutzern ging wesentlich auf die Systemsoftware zurück, die Gegenstand eines anderen
Beitrages ist [6].
The Telefunken TR 440 Computer was, at its deployment in 1970, the fastest machine developed and manufactured so far in Europe. 46 of them were installed in scientific institutions, agencies, and industry. The TR 440 was the successor of the TR 4 of 1962, which on the same market had gained an important position by its performance and its innovative compiler concept. TR 440 was designed for timesharing operation. The machine was one of the first large scale computers to use integrated circuits. It had page addressing and a refined system of privileged functions. The instruction rate approached 1 Mips, the main memory had a capacity of 1.5 MB. Point of departure, structure and technology are described from the point of view of today. A follow-on product, TR 550, was conceived but not developed. The appreciation TR 440 gained among its users was primarily due to its system software, which is described in a further paper [6]. TR 440 structure and technology is also subject of a paper submitted to the IEEE Annals of the History of Computing.相似文献
9.
Distributed top-k query processing is increasingly becoming an essential functionality in a large
number of emerging application classes. This paper addresses the efficient algebraic optimization of
top-k queries in wide-area distributed data repositories where the index lists for the attribute values
(or text terms) of a query are distributed across a number of data peers and the computational
costs include network latency, bandwidth consumption, and local peer work. We use a dynamic programming
approach to find the optimal execution plan using compact data synopses for selectivity estimation that
is the basis for our cost model. The optimized query is executed in a hierarchical way involving
a small and fixed number of communication phases. We have performed experiments on real web data
that show the benefits of distributed top-k query optimization both in network resource consumption
and query response time. 相似文献
10.
Colin Williams Pieter Kok Hwang Lee Jonathan P. Dowling 《Informatik - Forschung und Entwicklung》2006,70(3):73-82
Quantum information theory holds the promise of revolutionizing technologies other than computing
and communications. In this article we show how quantum entanglement can be harnessed to beat the Rayleigh
diffraction limit of conventional optical lithography, and to permit nano-devices to be fabricated at a scale
arbitrarily shorter than the wavelength used. Given the relative ease of performing optical lithography
compared with other schemes, and the relative costs associated in migrating the lithography industry to
each new fabrication technology, exploiting quantum entanglement to extend the useful life of optical lithography
could be economically attractive. 相似文献
11.
Christian Mathis 《Informatik - Forschung und Entwicklung》2007,11(3):147-164
Over the recent years, very little effort has been made to give XPath a proper algebraic treatment.
One laudable exception is the Natix Algebra (NAL) which defines the translation of XPath queries into algebraic
expressions in a concise way, thereby enabling algebraic optimizations. However, NAL does not capture
various promising core XML query evaluation algorithms like, for example, the Holistic Twig Join. By integrating
a logical structural join operator, we enable NAL to be compiled into a physical algebra containing
exactly those missing physical operators. We will provide several important query unnesting rules and demonstrate
the effectivity of our approach by an implementation in the XML Transaction Coordinator (XTC) – our
prototype of a native XML database system. 相似文献
12.
This paper highlights certain vital variables that can affect attitudes of librarians. It discusses the relationships between knowledge, training/experience of librarians on the use of computers and their attitudes towards the computer. One hundred and eighty-seven librarians participated in the study. A chi-square analysis was used to test the relationships. The results indicated that there are significant relationships between these variables and attitudes towards the computer. This means that previous training experience and present usage (knowledge of computer usage) of computers at work influence a positive attitude towards the computer. It is suggested that library schools should ensure adequate training and re-training programmes and that libraries should be equipped with state-of-the-art computer facilities so as to encourage staff usage of such facilities. 相似文献
13.
Jaakko Suominen & Jussi Parikka 《Media History》2013,19(3):319-340
The paper focuses on the emergence of Finnish computer culture in the late 1950s. The introduction of computers is studied by using a wide range of source material of popular media, such as commercial and company promotion films, newspapers, popular magazine articles, cartoons and comic strips. The paper argues that the introduction of the new computing technology was deeply experienced with the help of popular media, where the technological capabilities of computers as thinking and sensing ‘all-purpose machines’ were translated into several media-specific audio-visual forms. Computers were represented as sensing and sensible technology, a rubric that was remediated by the help of old media. In this process, the spectacularization of computers worked not only as an innocent fabulation of the computers to convince the ‘general public’ but to create a certain social arrangement particular to this spectacle. The idea that the end-user is cut off from the actual processes of the computer, as suggested by such media historians as Friedrich Kittler, was evident already in the earlier construction of computing culture in the mainframe era. 相似文献
14.
Model checking techniques are recognized to provide reliable and copious results. Instead of examining
a few cases only – as it is done in testing – model checking includes the whole state space
in mathematical proofs of correctness. Yet, this completeness is seen as a drawback as the state explosion
problem is hard to handle. In our industrial case study, we apply automated model checking techniques to
an innovative elevator system, the TWIN by ThyssenKrupp. By means of abstraction and nondeterminism, we
cope with runtime behaviour and achieve to efficiently prove our specification’s validity. The elevator’s
safety requirements are exhaustively expressed in temporal logic along with real-world and algorithmic prerequisites,
consistency properties, and fairness constraints. Beyond verifying system safety for an actual installation,
our case study demonstrates the rewarding applicability of model checking at an industrial scale.
CR subject classification D.2.4; F.3.1; J.7 ; C.3 相似文献
15.
Model checking techniques are recognized to provide reliable and copious results. Instead of examining
a few cases only – as it is done in testing – model checking includes the whole state space
in mathematical proofs of correctness. Yet, this completeness is seen as a drawback as the state explosion
problem is hard to handle. In our industrial case study, we apply automated model checking techniques to
an innovative elevator system, the TWIN by ThyssenKrupp. By means of abstraction and nondeterminism, we
cope with runtime behaviour and achieve to efficiently prove our specification’s validity. The elevator’s
safety requirements are exhaustively expressed in temporal logic along with real-world and algorithmic prerequisites,
consistency properties, and fairness constraints. Beyond verifying system safety for an actual installation,
our case study demonstrates the rewarding applicability of model checking at an industrial scale. 相似文献
16.
为解决搜索引擎结果繁杂而导致的浏览性不高的问题,提出一个基于用户行为学习的元搜索框架和结果聚类方法,并加以详细描述。利用该框架与方法,可以实时搜集用户行为进行推理学习,将学习到的有效知识存入知识库用以指导结果聚类,并随着用户的搜索过程不断调整完善。原型系统证明该方法是可行有效的。 相似文献
17.
18.
图书馆读者用机软件系统保护方法探析 总被引：4，自引：0，他引：4
杨勇 《现代图书情报技术》2002,18(1):82-84
随着计算机在图书馆的广泛使用, 提供给读者直接使用的计算机也日渐增多, 如何对这些公用计算机系统进行维护管理成了管理员最为棘手的一个问题。本文针对这一问题, 就W indow s95ö9 8 环境下计算机软件系统的保护方法作了一些分析探讨, 以期通过比较各种方法的特点, 对计算机的维护管理者提供一些参考。 相似文献
19.
Background: Pharmacy is an information intensive profession and a pharmacist has to be proficient in health care information management. The advance in information technology and the use of computers to access, retrieve and analyse this information is increasingly important. Yet little is known about pharmacists’ computer literacy or information technology skills. Objectives: To gain a better understanding of pharmacists’ basic computer skills and their ability to use standard software. Methods: Self‐administered postal survey to 747 registered pharmacists residing in two counties of England. Results: A total of 386 (52%) pharmacists responded after two mailings. Most responding pharmacists used computers at work and at home. They believed their basic computing skills to be high, although acknowledged that they were skill deficient in using certain software packages. Internet use at work was low (43%) as too was awareness and use of online medical databases; this was reflected in online medical database training being identified as of greatest need. Conclusions: Pharmacists were confident in operating computer systems but identified a training need for particular software applications. Of concern is the limited knowledge they possessed and access they had on medical databases. 相似文献