scholarly journals Understanding the Performance Guarantee of Physical Topology Design for Optical Circuit Switched Data Centers

2021 ◽  
Vol 5 (3) ◽  
pp. 1-24
Author(s):  
Shizhen Zhao ◽  
Peirui Cao ◽  
Xinbing Wang
Keyword(s):  
Data Centers ◽  
Topology Design ◽  
Performance Guarantee ◽  
Performance Limit ◽  
Coupling Technique ◽  
Performance Guarantees ◽  
Performance Metric ◽  
Optical Circuit ◽  
And Performance ◽  
The Ideal

As a first step of designing O ptical-circuit-switched D ata C enters (ODC), physical topology design is critical as it determines the scalability and the performance limit of the entire ODC. However, prior works on ODC have not yet paid much attention to physical topology design, and the adopted physical topologies either scale poorly, or lack performance guarantee. We offer a mathematical foundation for the design and performance analysis of ODC physical topologies in this paper. We introduce a new performance metric β(G ) to evaluate the gap between a physical topology G and the ideal physical topology. We develop a coupling technique that bypasses a significant amount of computational complexity of calculating β(G). Using β(G ) and the coupling technique, we study four physical topologies that are representative of those in literature, analyze their scalabilities and prove their performance guarantees. Our analysis may provide new guidance for network operators to design better physical topologies for their ODCs.

scholarly journals Efficiency Analysis of Government Subsidy and Performance Guarantee Policies in Relation to PPP Infrastructure Projects

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Lei Shi ◽  
Yujia He ◽  
Masamitsu Onishi ◽  
Kiyoshi Kobayashi
Keyword(s):  
Government Subsidy ◽  
Performance Guarantee ◽  
Infrastructure Projects ◽  
Special Purpose Vehicle ◽  
Performance Guarantees ◽  
Sustainable Operation ◽  
Integrated Policy ◽  
The Government ◽  
And Performance ◽  
Liquidity Shock

Sustainable operation of public-private partnership (PPP) infrastructure projects that are characterized by considerable external benefits is of vital importance. However, a liquidity shock might trigger an inefficient liquidation of a project by the special purpose vehicle (SPV) and the bank, whose objectives are to maximize the profits generated by the project. This study argues that performance guarantee and subsidy policies implemented by the government play a role in encouraging socially efficient decision-making by the SPV and the bank to ensure the continuation of socially valuable projects. The results show that both government subsidy and performance guarantee policies are effective in avoiding the inefficient liquidation of PPP infrastructure projects when the external benefits are large and certain. However, a performance guarantee policy might lead to inefficient continuation when the external benefits of a project are uncertain. Finally, we discuss the possibility that an integrated policy combining performance guarantees and government subsidies improves the efficiency of a PPP infrastructure project.

scholarly journals STRICT CONFORMITY OF DOCUMENTS UNDER A PERFORMANCE GUARANTEE. DOES A SIGNED COPY OF A DOCUMENT QUALIFY AS AN ORIGINAL? Stefanutti & Bressan (Pty) Ltd v Nedbank Ltd (unreported judgment delivered on 30 July 2008) (case no 5311/2008) (D&CLD)

Obiter ◽  
2021 ◽  
Vol 30 (2) ◽  
Author(s):  
WG Schulze
Keyword(s):  
South African ◽  
Case Law ◽  
Performance Guarantee ◽  
High Court ◽  
Bond Performance ◽  
Performance Guarantees ◽  
Kwazulu Natal ◽  
Letters Of Credit ◽  
And Performance

Unlike in many overseas jurisdictions, there is a paucity of South African reported case law dealing with certain instruments of payment and guarantees for payment such as documentary letters of credit and performance guarantees, to mention but two examples of instruments prevalent in the field of payment and financing. For this reason any new case law dealing with either letters of credit or performance guarantees is to be welcomed as it would hopefully not only contribute to our understanding of this area of the law, but also provide an opportunity for comment and reflection. This holds especially true since the International Chamber of Commerce has recently (in July 2007) accepted and introduced a new version of the Uniform Customs and Practices for Documentary Credits (hereinafter “the UCP”): UCP 600. In passing: Apart from the main distinction between direct (three-party) and indirect (four-party) demand guarantees, they (ie, demand guarantees) may also be classified by reference to the phase or part of performance theyare designed to secure, hence the following classification of the different types of demand guarantees: tender guarantee (tender bond); performance guarantee (performance bond); advance payment guarantee (repayment guarantee); retention guarantee; and maintenance guarantee (warranty guarantee). In what follows below the author will use the concept of “guarantee”, being a genericterm, when referring to demand and/or performance guarantees in general. The recent decision in Stefanutti & Bressan (Pty) Ltd v Nedbank Ltd (unreported judgment delivered on 30 July 2008 (case no 5311/2008) by the Durban & Coast Local Division of the High Court (now: KwaZulu-Natal High Court, Durban) is a rare and welcome addition to the rather modest collection of South African decisions dealing with performance guarantees.

scholarly journals Evaluation of the Legal Framework for Building Fire Safety Regulations in Spain

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 51
Author(s):  
Amaya Osácar ◽  
Juan Bautista Echeverria Trueba ◽  
Brian Meacham
Keyword(s):  
Fire Safety ◽  
Risk Mitigation ◽  
Fire Risk ◽  
Legal Framework ◽  
Regulatory Framework ◽  
Existing Building ◽  
Building Fire ◽  
Safety Regulations ◽  
And Performance ◽  
The Ideal

There is a trend in Europe towards increasing the quality and performance of regulations. At the same time, regulatory failure has been observed in the area of building fire safety regulation in England and elsewhere. As a result, an analysis of the appropriateness of fire safety regulations in Spain is warranted, with the objective being to assess whether a suitable level of fire safety is currently being delivered. Three basic elements must be considered in such analysis: the legal and regulatory framework, the level of fire risk/safety of buildings that is expected and the level which actually results, and a suitable method of analysis. The focus of this paper is creating a legal and regulatory framework, in particular with respect to fire safety in buildings. Components of an ”ideal” building regulatory framework to adequately control fire risk are presented, the existing building regulatory framework is summarized, and an analysis of the gaps between the ideal and the existing systems is presented. It is concluded that the gaps between the ideal and the existing framework are significant, and that the current fire safety regulations are not appropriate for assuring delivery of the intended level of fire risk mitigation.

Load-Optimization in Reconfigurable Networks

2021 ◽  
Vol 48 (3) ◽  
pp. 39-44 ◽  
Author(s):  
Wenkai Dai ◽  
Klaus-Tycho Foerster ◽  
David Fuchssteiner ◽  
Stefan Schmid
Keyword(s):  
Data Centers ◽  
Algorithmic Problem ◽  
Reconfigurable Networks ◽  
Load Optimization ◽  
Clos Networks ◽  
Optical Circuit ◽  
Tree Topologies ◽  
Packet Switch ◽  
Routing Policies

Emerging reconfigurable data centers introduce the unprecedented flexibility in how the physical layer can be programmed to adapt to current traffic demands. These reconfigurable topologies are commonly hybrid, consisting of static and reconfigurable links, enabled by e.g. an Optical Circuit Switch (OCS) connected to top-of-rack switches in Clos networks. Even though prior work has showcased the practical benefits of hybrid networks, several crucial performance aspects are not well understood. In this paper, we study the algorithmic problem of how to jointly optimize topology and routing in reconfigurable data centers with a known traffic matrix, in order to optimize a most fundamental metric, maximum link load. We chart the corresponding algorithmic landscape by investigating both un-/splittable flows and (non-)segregated routing policies. We moreover prove that the problem is not submodular for all these routing policies, even in multi-layer trees, where a topological complexity classification of the problem reveals that already trees of depth two are intractable. However, networks that can be abstracted by a single packet switch (e.g., nonblocking Fat-Tree topologies) can be optimized efficiently, and we present optimal polynomialtime algorithms accordingly. We complement our theoretical results with trace-driven simulation studies, where our algorithms can significantly improve the network load in comparison to the state of the art.

Selecting the Parameters for Brazing 08 Steel with Pure Copper Solder Paste

2010 ◽  
Vol 426-427 ◽  
pp. 432-435
Author(s):  
De Gong Chang ◽  
J. Zhang ◽  
M.L. Lv
Keyword(s):  
Carbon Steel ◽  
Filler Metal ◽  
Pure Copper ◽  
Low Carbon Steel ◽  
Solder Paste ◽  
Low Carbon ◽  
Technical Parameters ◽  
And Performance ◽  
Steel Joints ◽  
The Ideal

The larger variation of the construction and performance of the low-carbon steel joints was caused by the high temperature of the puddle welding of the joint. Therefore, the braze welding rather than the puddle welding was applied to the welding production of low-carbon steel. The 08 steel parts were joined in a furnace using pure copper solder paste as brazing filler metal. According to the obtained results, the ideal technical parameters are as follow: brazing temperature: 1100-1150°C; holding time: 5-10min; joint clearance: 0.03-0.05mm.

Development of Team Coordination and Performance Measures in a Trauma Setting

2007 ◽  
Vol 51 (11) ◽  
pp. 717-721 ◽  
Author(s):  
Stuart Marshall ◽  
Anne Miller ◽  
Yan Xiao
Keyword(s):  
Team Performance ◽  
Decision Support Tool ◽  
Stage Model ◽  
Trauma Resuscitation ◽  
Team Coordination ◽  
Support Tool ◽  
University Of Maryland ◽  
Performance Metric ◽  
And Performance ◽  
The University

The paucity of reliable measures of team coordination and performance significantly obstructs the assessment of the effects of any technology on teams to improve decision making in health care. A pilot study was conducted to determine if measures of coordination and performance could be developed for teams involved in trauma resuscitation. A video assisted review of cases enabled evaluation of the use of the tools. Descriptors of coordination were derived from Klein's five-stage model of team coordination. A scoring system of team performance was developed from the University of Maryland Team Observable Performance Metric (UMTOP). After some modification both coordination and performance could be described. However, four defined stages of resuscitation were observed which greatly improved coding. More rigorous assessments of these tools will be required before firm conclusions can be drawn about the effects of a decision support tool recently introduced into the environment.

A fault-tolerant control scheme within adaptive disturbance observer for hypersonic vehicle

2017 ◽  
Vol 233 (3) ◽  
pp. 1071-1088 ◽  
Author(s):  
Jun Zhou ◽  
Jing Chang ◽  
Zongyi Guo
Keyword(s):  
Disturbance Observer ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Lyapunov Theory ◽  
Sliding Mode Controller ◽  
Performance Guarantees ◽  
Uncertain Model ◽  
Control Scheme ◽  
And Performance

The paper describes the design of a fault-tolerant control scheme for an uncertain model of a hypersonic reentry vehicle subject to actuator faults. In order to improve superior transient performances for state tracking, the proposed method relies on a back-stepping sliding mode controller combined with an adaptive disturbance observer and a reference vector generator. This structure allows for a faster response and reduces the overshoots compared to linear conventional disturbance observers based sliding mode controller. Robust stability and performance guarantees of the overall closed-loop system are obtained using Lyapunov theory. Finally, numerical simulations results illustrate the effectiveness of the proposed technique.

Sign in / Sign up

Export Citation Format

Share Document