scholarly journals Reasoning about the garden of forking paths

2021 ◽  
Vol 5 (ICFP) ◽  
pp. 1-28
Author(s):  
Yao Li ◽  
Li-yao Xia ◽  
Stephanie Weirich
Keyword(s):  
Computational Cost ◽  
Recent Model ◽  
Lazy Evaluation ◽  
On Demand ◽  
Evaluation Strategies ◽  
Definition Of ◽  
Concise Expression

Lazy evaluation is a powerful tool for functional programmers. It enables the concise expression of on-demand computation and a form of compositionality not available under other evaluation strategies. However, the stateful nature of lazy evaluation makes it hard to analyze a program's computational cost, either informally or formally. In this work, we present a novel and simple framework for formally reasoning about lazy computation costs based on a recent model of lazy evaluation: clairvoyant call-by-value. The key feature of our framework is its simplicity, as expressed by our definition of the clairvoyance monad. This monad is both simple to define (around 20 lines of Coq) and simple to reason about. We show that this monad can be effectively used to mechanically reason about the computational cost of lazy functional programs written in Coq.

Personal Storage Grid Architecture

2012 ◽  
pp. 97-109
Author(s):  
Mian-Guan Lim ◽  
Sining Wu ◽  
Tomasz Simon ◽  
Md Rashid ◽  
Na Helian
Keyword(s):  
Web Service ◽  
File System ◽  
File Systems ◽  
System Support ◽  
End User ◽  
Operation System ◽  
Disk Space ◽  
On Demand ◽  
Definition Of ◽  
Cloud Applications

On-demand cloud applications like online email accounts and online virtual disk space are becoming widely available in various forms. In cloud applications, one can see the importance of underlying resources, such as disk space, that is available to the end-user but not easily accessible. In the authors’ study, a modern file system developed in linux is proposed, which enables consuming of cloud applications and making the underlying disk space resource available to the end-user. This system is developed as a web service to support cross operation system support. A free online mail account was used to demonstrate this solution, and an IMAP protocol to communicate with remote data spaces was used so that this method can mount onto any email system that supports IMAP. The authors’ definition of infinite storage as the user is able to mount file systems as a single logical drive.

A Subspace-Projected Approximate Matrix Method for Systems of Linear Equations

2013 ◽  
Vol 3 (2) ◽  
pp. 120-137 ◽  
Author(s):  
Jan Brandts ◽  
Ricardo R. da Silva
Keyword(s):  
Matrix Method ◽  
Eigenvalue Problems ◽  
Linear Equations ◽  
Computational Cost ◽  
Systems Of Linear Equations ◽  
Definition Of ◽  
Specific Sense ◽  
Low Computational Cost ◽  
Minimal Residual Methods ◽  
Linear Systems Of Equations

AbstractGiven two n × n matrices A and A0 and a sequence of subspaces with dim the k-th subspace-projected approximated matrix Ak is defined as Ak = A + Πk(A0 − A)Πk, where Πk is the orthogonal projection on . Consequently, Akν = Aν and ν*Ak = ν*A for all Thus is a sequence of matrices that gradually changes from A0 into An = A. In principle, the definition of may depend on properties of Ak, which can be exploited to try to force Ak+1 to be closer to A in some specific sense. By choosing A0 as a simple approximation of A, this turns the subspace-approximated matrices into interesting preconditioners for linear algebra problems involving A. In the context of eigenvalue problems, they appeared in this role in Shepard et al. (2001), resulting in their Subspace Projected Approximate Matrix method. In this article, we investigate their use in solving linear systems of equations Ax = b. In particular, we seek conditions under which the solutions xk of the approximate systems Akxk = b are computable at low computational cost, so the efficiency of the corresponding method is competitive with existing methods such as the Conjugate Gradient and the Minimal Residual methods. We also consider how well the sequence (xk)k≥0 approximates x, by performing some illustrative numerical tests.

scholarly journals Cost-Effective Edge Server Placement in Wireless Metropolitan Area Networks

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 32 ◽  
Author(s):  
Feng Zeng ◽  
Yongzheng Ren ◽  
Xiaoheng Deng ◽  
Wenjia Li
Keyword(s):  
Metropolitan Area ◽  
Dominating Set ◽  
Cost Effective ◽  
Mobile Users ◽  
Metropolitan Area Networks ◽  
New Paradigm ◽  
Long Distance ◽  
On Demand ◽  
Wireless Metropolitan Area Networks ◽  
Definition Of

Remote clouds are gradually unable to achieve ultra-low latency to meet the requirements of mobile users because of the intolerable long distance between remote clouds and mobile users and the network congestion caused by the tremendous number of users. Mobile edge computing, a new paradigm, has been proposed to mitigate aforementioned effects. Existing studies mostly assume the edge servers have been deployed properly and they just pay attention to how to minimize the delay between edge servers and mobile users. In this paper, considering the practical environment, we investigate how to deploy edge servers effectively and economically in wireless metropolitan area networks. Thus, we address the problem of minimizing the number of edge servers while ensuring some QoS requirements. Aiming at more consistence with a generalized condition, we extend the definition of the dominating set, and transform the addressed problem into the minimum dominating set problem in graph theory. In addition, two conditions are considered for the capacities of edge servers: one is that the capacities of edge servers can be configured on demand, and the other is that all the edge servers have the same capacities. For the on-demand condition, a greedy based algorithm is proposed to find the solution, and the key idea is to iteratively choose nodes that can connect as many other nodes as possible under the delay, degree and cluster size constraints. Furthermore, a simulated annealing based approach is given for global optimization. For the second condition, a greedy based algorithm is also proposed to satisfy the capacity constraint of edge servers and minimize the number of edge servers simultaneously. The simulation results show that the proposed algorithms are feasible.

Mini-Max Type Formulation of Strict Robust Design Optimization Under Correlative Variation

2002 ◽  
Author(s):  
Noriyasu Hirokawa ◽  
Kikuo Fujita
Keyword(s):  
Design Optimization ◽  
Robust Design ◽  
Design Space ◽  
Computational Cost ◽  
Robust Design Optimization ◽  
Maximization Problem ◽  
Quadratic Polynomials ◽  
Feasibility Assessment ◽  
Design Variation ◽  
Definition Of

This paper proposes a mini-max type formulation for strict robust design optimization under correlative variation based on design variation hyper sphere and quadratic polynomial approximation. While various types of formulations and techniques have been developed for computational robust design, they confront the compromise among modeling of parameter variation, feasibility assessment, definition of optimality such as sensitivity, and computational cost. The formulation of this paper aims that all points within the distribution region are thoroughly optimized. For this purpose, the design space with correlative variation is diagonalized and isoparameterized into a hyper sphere, and the functions of nominal constraints and the nominal objective are modeled as quadratic polynomials. These transformation and approximation enable the analytical discrimination of inner or boundary type on the worst design and its quantified values with less computation cost under a certain condition, and bring the procedural definition of the strictly robust optimality of a design as a maximization problem. The minimization of this formulation, that is, mini-max type optimization, can find the robust design under the above meaning. Its validity is ascertained through numerical examples.

scholarly journals On a new Wigner-Ville distribution associated with linear canonical transform

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Hong-Cai Xin ◽  
Bing-Zhao Li
Keyword(s):  
Modulation Frequency ◽  
Computational Cost ◽  
Estimation Method ◽  
Superior Performance ◽  
Linear Canonical Transform ◽  
Two Phase ◽  
Cross Term ◽  
Time Frequency ◽  
Definition Of ◽  
Non Stationary Signal

AbstractLinear canonical transform as a general integration transform has been considered into Wigner-Ville distribution (WVD) to show more powerful ability for non-stationary signal processing. In this paper, a new WVD associated with linear canonical transform (WVDL) and integration form of WVDL (IWVDL) are presented. First, the definition of WVDL is derived based on new autocorrelation function and some properties are investigated in details. It removes the coupling between time and time delay and lays the foundation for signal analysis and processing. Then, based on the characteristics of WVDL over time-frequency plane, a new parameter estimation method, IWVDL, is proposed for linear modulation frequency (LFM) signal. Two phase parameters of LFM signal are estimated simultaneously and the cross term can be suppressed well by integration operator. Finally, compared with classical WVD, the simulation experiments are carried out to verify its better estimation and suppression of cross term ability. Error analysis and computational cost are discussed to show superior performance compared with other WVD in linear canonical transform domain. The further application in radar imaging field will be studied in the future work.

Dynamic behaviour of bridges under critical articulated trains: Signature and bogie factor applied to the review of some regulations included in EN 1991-2

2020 ◽  
pp. 095440972095647
Author(s):  
Pedro Museros ◽  
Andreas Andersson ◽  
Victor Martí ◽  
Raid Karoumi
Keyword(s):  
High Speed ◽  
Computational Cost ◽  
Detailed Knowledge ◽  
Railway Bridges ◽  
Simply Supported ◽  
Load Models ◽  
Theoretical Approaches ◽  
Accurate Definition ◽  
Essential Components ◽  
Definition Of

The information contained in this paper will be of interest not only to bridge engineers, but also to train manufacturers. The article provides practical insight into the degree of coverage of real articulated trains (ATs) that Eurocode EN1991-2 guarantees. In both the design of new railway bridges, as well as in the assessment of existing ones, the importance of a detailed knowledge of the limits of validity of load models cannot be overemphasised. Being essential components of the rail transportation system, the capacity of bridges to withstand future traffic demands will be determined precisely by the load models. Therefore, accurate definition of the limits of validity of such models reveals crucial when increased speeds and/or increased axle loads are required by transportation pressing priorities. The most relevant load model for a significant portion of the bridges in high-speed railway lines is the so-called HSLM-A model, defined in EN1991-2. Their limits of validity are described in Annex E of such code. For its singular importance, the effects of vibrations induced by HSLM-A are analysed in this paper with attention to the response of simply supported bridges. This analysis is carried out in a view to determine whether the limits of validity given in Annex E of EN1991-2 cover the largest part of cases of interest. Specifically, the vibration effects of HSLM-A are compared with those of the ATs described in such Annex E, and the response is analysed in depth for simply supported bridges, which are structures especially sensitive to passing trains at high speeds. New theoretical approaches have been developed in order to undertake this investigation, including a novel, simplified expression of the train signature for ATs that is convenient for its low computational cost. The mathematical proofs are included in the first part of the paper and two separate appendices.

scholarly journals Review article: The use of remotely piloted aircraft systems (RPAS) for natural hazards monitoring and management

2017 ◽  
Author(s):  
Daniele Giordan ◽  
Yuichi Hayakawa ◽  
Francesco Nex ◽  
Fabio Remondino ◽  
Paolo Tarolli
Keyword(s):  
Natural Hazards ◽  
Review Article ◽  
Emergency Operations ◽  
On Demand ◽  
Aircraft Systems ◽  
Scientific Experiments ◽  
Remotely Piloted Aircraft ◽  
High Resolution Images ◽  
Definition Of ◽  
Active Processes

Abstract. The number of scientific studies that consider possible applications of Remotely Piloted Aircraft Systems (RPAS) for the management of natural hazards effects and the identification of occurred damages are strongly increased in last decade. Nowadays, in the scientific community, the use of these systems is not a novelty, but a deeper analysis of literature shows a lack of codified complex methodologies that can be used not only for scientific experiments but also for normal codified emergency operations. RPAS can acquire on-demand ultra-high resolution images that can be used for the identification of active processes like landslides or volcanic activities but also for the definition of effects of earthquakes, wildfires and floods. In this paper, we present a review of published literature that describes experimental methodologies developed for the study and monitoring of natural hazards.

Elements for a Legal Definition of Commercial Banking: A Comparative View

1981 ◽  
Vol 16 (4) ◽  
pp. 499-515 ◽  
Author(s):  
Ricardo Ben-Oliel
Keyword(s):  
Commercial Banking ◽  
Legal Rule ◽  
The Public ◽  
Legal Definition ◽  
On Demand ◽  
High Commissioner ◽  
Banking Business ◽  
Economic Reality ◽  
Definition Of ◽  
The Right

In 1941, the Banking Ordinance enacted by the High Commissioner of Palestine defined “banking business” as the “business of receiving from the public on current account money which is to be repayable on demand by check, and of making advances to customers”. The most recently enacted Israeli Banking Law (Licensing), 1981 contains a very extensive definition of banking business which includes no less than thirteen types of transactions.This certainly reflects a new legal approach towards the economic reality of banking which in and of itself has not changed drastically. Moreover, the peculiar dynamics of the banking business also inspired the legal rule that the Governor of the Bank of Israel should have the right to enlarge the legal definition by recognizing the banking character of other transactions.

scholarly journals Thermal analysis of blood flow of Newtonian, pseudo-plastic, and dilatant fluids through an inclined wavy channel due to metachronal wave of cilia

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110490
Author(s):  
Abdou Al-Zubaidi ◽  
Mubbashar Nazeer ◽  
Khadija Khalid ◽  
Sidra Yaseen ◽  
Salman Saleem ◽  
...  
Keyword(s):  
Biological Fluids ◽  
Nonlinear Partial Differential Equations ◽  
Medical Science ◽  
Computational Cost ◽  
Physical Parameters ◽  
Convective Boundary ◽  
Definition Of ◽  
Dilatant Fluid ◽  
The Mathematical Model ◽  
Low Computational Cost

This paper is organized to study the heat and mass transfer analyses by considering the motion of cilia for Newtonian, Pseudo-plastic, and Dilatant fluids through a horizontally inclined channel in the presence of metachronal waves and variable liquid properties. A non-Newtonian Rabinowitsch model is used to study the flow of peristalsis through ciliated walls. The slip and convective boundary conditions at the channel walls are taken into account. The mathematical model is developed in the form of complex nonlinear partial differential equations then transformed into simplified form by using the definition of low-Reynolds number with lubrication theory. The analytical solution is obtained by using the perturbation method due to its low computational cost and good accuracy. The graphical outcome is based on the behavior of certain physical parameters on velocity, temperature, and concentration profiles for all three types of fluid. A symbolic software named MATHEMATICA 12.0 is used to find the analytical expression and construct the graphical behavior of all profiles that are taken under discussion. The important results in this study depict that the velocity profile tends to increase in the central region of the channel for Newtonian and Pseudo-plastic fluids and decreases for Dilatant fluid while a reverse behavior is observed near the channel walls. A smaller wavelength causes the wavenumber to accelerate and it tends to decelerate for a larger wavelength. The current study will help to understand the use of the complex rheological behavior of biological fluids in engineering and medical science.

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