778 research outputs found
Performance of Glass Resistive Plate Chambers for a high granularity semi-digital calorimeter
A new design of highly granular hadronic calorimeter using Glass Resistive
Plate Chambers (GRPCs) with embedded electronics has been proposed for the
future International Linear Collider (ILC) experiments. It features a 2-bit
threshold semi-digital read-out. Several GRPC prototypes with their electronics
have been successfully built and tested in pion beams. The design of these
detectors is presented along with the test results on efficiency, pad
multiplicity, stability and reproducibility.Comment: 16 pages, 15 figure
High rate, fast timing Glass RPC for the high {\eta} CMS muon detectors
The HL-LHC phase is designed to increase by an order of magnitude the amount
of data to be collected by the LHC experiments. To achieve this goal in a
reasonable time scale the instantaneous luminosity would also increase by an
order of magnitude up to . The region of the forward
muon spectrometer () is not equipped with RPC stations. The
increase of the expected particles rate up to (including a
safety factor 3) motivates the installation of RPC chambers to guarantee
redundancy with the CSC chambers already present. The actual RPC technology of
CMS cannot sustain the expected background level. The new technology that will
be chosen should have a high rate capability and provides a good spatial and
timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity
(LR) glass is proposed to equip at least the two most far away of the four high
muon stations of CMS. First the design of small size prototypes and
studies of their performance in high-rate particles flux is presented. Then the
proposed designs for large size chambers and their fast-timing electronic
readout are examined and preliminary results are provided.Comment: 14 pages, 11 figures, Conference proceeding for the 2016 Resistive
Plate Chambers and Related Detector
TensorFlow Doing HPC
TensorFlow is a popular emerging open-source programming framework supporting
the execution of distributed applications on heterogeneous hardware. While
TensorFlow has been initially designed for developing Machine Learning (ML)
applications, in fact TensorFlow aims at supporting the development of a much
broader range of application kinds that are outside the ML domain and can
possibly include HPC applications. However, very few experiments have been
conducted to evaluate TensorFlow performance when running HPC workloads on
supercomputers. This work addresses this lack by designing four traditional HPC
benchmark applications: STREAM, matrix-matrix multiply, Conjugate Gradient (CG)
solver and Fast Fourier Transform (FFT). We analyze their performance on two
supercomputers with accelerators and evaluate the potential of TensorFlow for
developing HPC applications. Our tests show that TensorFlow can fully take
advantage of high performance networks and accelerators on supercomputers.
Running our TensorFlow STREAM benchmark, we obtain over 50% of theoretical
communication bandwidth on our testing platform. We find an approximately 2x,
1.7x and 1.8x performance improvement when increasing the number of GPUs from
two to four in the matrix-matrix multiply, CG and FFT applications
respectively. All our performance results demonstrate that TensorFlow has high
potential of emerging also as HPC programming framework for heterogeneous
supercomputers.Comment: Accepted for publication at The Ninth International Workshop on
Accelerators and Hybrid Exascale Systems (AsHES'19
Towards portable muography with small-area, gas-tight glass Resistive Plate Chambers
Imaging techniques that use atmospheric muons, collectively named under the
neologism "muography", have seen a tremendous growth in recent times, mainly
due to their diverse range of applications. The most well-known ones include
but are not limited to: volcanology, archaeology, civil engineering, nuclear
reactor monitoring, nuclear waste characterization, underground mapping, etc.
These methods are based on the attenuation or deviation of muons to image large
and/or dense objects where conventional techniques cannot work or their use
becomes challenging.
In this context, we have constructed a muography telescope based on "mini
glass-RPC planes" following a design similar to the glass-RPC detectors
developed by the CALICE Collaboration and used by the TOMUVOL experiment in the
context of volcano radiography, but with smaller active area (16 16
cm). The compact size makes it an attractive choice with respect to other
detectors previously employed for imaging on similar scales. An important
innovation in this design is that the detectors are sealed. This makes the
detector more portable and solves the usual safety and logistic issues for gas
detectors operated underground and/or inside small rooms. This paper provides
an overview on our guiding principles, the detector development and our
operational experiences. Drawing on the lessons learnt from the first
prototype, we also discuss our future direction for an improved second
prototype, focusing primarily on a recently adopted serigraphy technique for
the resistive coating of the glass plates.Comment: 8 pages, 7 figures, XV Workshop on Resistive Plate Chambers and
Related Detectors (RPC2020
Selective and unspecific expropriation of foreign direct investments: Empir. evidence and implications for the debt crisis
The persistence of the.international debt crisis has given rise to considerations that foreign direct investment (FDD should play a larger role in the financing of less developed countries (LDCs) in the future. FDIs may provide external financing for developing countries even in times when new lending is restricted due to high credit risks. Flexible payment schedules and the extended property rights may differentiate FDIs from international loans and provide shelter against high country risks. However, FDIs are subject to sovereign risk as well. The option of sovereign states to defer loan repayments as soon as the.costs of contract fulfillment exceed the benefits has its counterpart in expropriations of FDI. The potential of substituting FDI for debt depends on the attitude of the LDCs1 governments towards FDI. A larger role for FDI, especially in times of restricted new lending, will only be possible if the political and economic situation of the borrowing country that induces creditors to expect a higher risk of willful default does not increase the risk of expropriations at the same time.
FairLedger: A Fair Blockchain Protocol for Financial Institutions
Financial institutions are currently looking into technologies for
permissioned blockchains. A major effort in this direction is Hyperledger, an
open source project hosted by the Linux Foundation and backed by a consortium
of over a hundred companies. A key component in permissioned blockchain
protocols is a byzantine fault tolerant (BFT) consensus engine that orders
transactions. However, currently available BFT solutions in Hyperledger (as
well as in the literature at large) are inadequate for financial settings; they
are not designed to ensure fairness or to tolerate selfish behavior that arises
when financial institutions strive to maximize their own profit.
We present FairLedger, a permissioned blockchain BFT protocol, which is fair,
designed to deal with rational behavior, and, no less important, easy to
understand and implement. The secret sauce of our protocol is a new
communication abstraction, called detectable all-to-all (DA2A), which allows us
to detect participants (byzantine or rational) that deviate from the protocol,
and punish them. We implement FairLedger in the Hyperledger open source
project, using Iroha framework, one of the biggest projects therein. To
evaluate FairLegder's performance, we also implement it in the PBFT framework
and compare the two protocols. Our results show that in failure-free scenarios
FairLedger achieves better throughput than both Iroha's implementation and PBFT
in wide-area settings
The Mikado Filesystem: An experimental RPC filesystem running over gRPC
Computer applications seeking to persist files remotely across the Internet
are faced with a bewildering choice of mechanisms which tend to boil down to
monolithic proprietary closed-source Vendor solutions. We introduce The Mikado
Filesystem (mikfs), which provides an open simple lightweight interoperable
portable extensible remote filesystem that is open source. mikfs consists of
client applications accessing remote servers via RPC running over TCP/IP
connections. mikfs is defined as a concrete set of API method calls over gRPC
expressed in Google's Protocol Buffers' IDL. gRPC supports a wide variety of
programming languages & platforms. For a given language + platform, the gRPC
toolset can generate client- & server-side stubs from the IDL callable from
client & server code in the selected languages, e.g., a client written in C# or
java running on a Windows PC can access a server written in C++ running on
Linux. mikfs consists of a virtual hierarchical tree of files & directories.
This logical filesystem is not constrained to the limits and file naming
conventions of the host's own physical native filesystem. API methods are
provided for authentication; for atomic file-level operations on files &
directories; for clients to register to receive notifications of file &
directory changes on a server. The public API allows developers to write their
own new servers and clients; allowing migration of hosted files between
different implementations; extension with new methods & features; is Open
Source code available for inspection and adaptation. gRPC provides secure
authenticated connection & communication over HTTP/2; End-to-End Privacy &
Security against eavesdropping of data in transit; support for multiple
alternate user login mechanisms. mikfs is provided as source code, 'The
Bootstrap Distribution', consisting of an ecosystem of clients, servers, tools
and utilities.Comment: 11 pages, 2 figure
API diversity for microservices in the domain of connected vehicles
Web services in the domain of connected vehicles are subject to various requirements including high availability and large workloads. Microservices are an architectural style which can fulfill those requirements by fostering the independence and decoupling of software components as reusable services. To achieve this independence, microservices have to implement all aspects of providing the services themselves, including different API technologies for heterogeneous consumers and supporting features like authentication. In this work, we examine the use of a service proxy that externalizes these concerns into a sidecar that provides multiple APIs and common service functionality in a platform-independent manner. We look at how different kinds of API styles and technologies solve selected classes of problems and how we can translate between API technologies. We design and implement a framework for building gateways that enables the creation and composition of reusable components, in the fashion of Lego bricks, to maximize flexibility, while reducing the effort for building gateway components. We design and implement selected components of common and reusable API functionality enabling us to build a reference setup with a service proxy as a sidecar using our framework. Finally, we evaluate the proposed solution to identify benefits and drawbacks of the approach of using our framework as a service proxy. We conclude that the examined approach provides benefits for the development of many polyglot microservices, but splitting one service into two components adds additional complexity that has to be managed.Web Services für vernetzte Fahrzeuge unterliegen unterschiedlichen Anforderungen, unter anderem einer hohen Verfügbarkeit und einem großen Datendurchsatz. Microservices sind ein Architekturstil, der diesen Anforderungen gerecht werden kann, indem er die Unabhängigkeit und Entkopplung von Softwarekomponenten als wiederverwendbare Services fördert. Zum Erreichen der Unabhängigkeit implementieren Microservices alle Aspekte der Servicebereitstellung eigenständig. Dazu gehört verschiedene API Technologien für heterogene Clients bereitzustellen und unterstützende Funktionalität wie Authentifizierung zu implementieren. In dieser Arbeit wird die Verwendung einer Proxy Komponente vor einem Service untersucht, durch welche die Bereitstellung verschiedener API Technologien und allgemeiner unterstützender Funktionalität aus dem Service extrahiert wird. Die Lösungen verschiedener API Technologien und Stile für ausgewählte Klassen an Problemen werden verglichen und mögliche Umwandlungen der verschiedenen API Technologien werden untersucht. Es wird ein Framework konzeptioniert und implementiert, das die Erstellung von Gateways durch Kombination von wiederverwendbaren Komponenten, wie das Zusammensetzen von Legosteinen, ermöglicht. Dieses Framework sorgt für eine hohe Flexibilität, während es den Aufwand bei der Erstellung von Gateways gering hält. Es werden ausgewählte wiederverwendbare Komponenten entworfen, um eine Referenzimplementierung des Ansatzes umzusetzen, bei der allgemeine Funktionalität in einen parallel laufenden Proxy ausgelagert wird. Dieser Ansatz wird evaluiert, indem Vor- und Nachteile anhand eines mit dem Framework erstellten Proxys identifiziert werden. Das Fazit dieser Arbeit ist, dass dieser Ansatz bei Systemen mit vielen Microservices mit unterschiedlichen Programmiersprachen Vorteile bringt, aber die Trennung eines Services in zwei Komponenten eine nicht unerhebliche Komplexität einführt
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