Standard Examples Research Articles

Integer Programming on the Junction Tree Polytope for Influence Diagrams

Influence diagrams (ID) and limited memory influence diagrams (LIMID) are flexible tools to represent discrete stochastic optimization problems, with the Markov decision process (MDP) and partially observable MDP as standard examples. More precisely, given random variables considered as vertices of an acyclic digraph, a probabilistic graphical model defines a joint distribution via the conditional distributions of vertices given their parents. In an ID, the random variables are represented by a probabilistic graphical model whose vertices are partitioned into three types: chance, decision, and utility vertices. The user chooses the distribution of the decision vertices conditionally to their parents in order to maximize the expected utility. Leveraging the notion of rooted junction tree, we present a mixed integer linear formulation for solving an ID, as well as valid inequalities, which lead to a computationally efficient algorithm. We also show that the linear relaxation yields an optimal integer solution for instances that can be solved by the “single policy update,” the default algorithm for addressing IDs.

Random bipartite posets and extremal problems

Previously, Erdős, Kierstead and Trotter [5] investigated the dimension of random height 2 partially ordered sets. Their research was motivated primarily by two goals: (1) analyzing the relative tightness of the Furedi–Kahn upper bounds on dimension in terms of maximum degree; and (2) developing machinery for estimating the expected dimension of a random labeled poset on n points. For these reasons, most of their effort was focused on the case $$0<p\le 1/2$$ . While bounds were given for the range $$1/2\le p <1$$ , the relative accuracy of the results in the original paper deteriorated as p approaches 1. Motivated by two extremal problems involving conditions that force a poset to contain a large standard example, we were compelled to revisit this subject, but now with primary emphasis on the range $$1/2\le p<1$$ . Our sharpened analysis shows that as p approaches 1, the expected value of dimension increases and then decreases, answering in the negative a question posed in the original paper. Along the way, we apply inequalities of Talagrand and Janson, establish connections with latin rectangles and the Euler product function, and make progress on both extremal problems.

Harmonic indices for continuous evaluation of consumer's harmonic contribution

Nowadays, the determination of the contribution of individual customers to the harmonic pollution of an electric power network is very essential for power quality improvement. In this study, four new indices are introduced to investigate the effect of harmonic contribution (HC) of the pollutant customers for an arbitrary time period without any access to a network model. These indices are defined according to data measured at the connection point of the suspicious loads and targeted buses under study. In this regard, a continuous HC matrix is developed where its entries are determined by using a new multi-point and continuous HC calculation method without having to measure the phase angle, which makes this method practical and cost-effective. The method and indices are applied to a standard power network-based calculation example. In addition, experimental measurements, which are gathered based on the Isfahan city and Iran electric power transmission systems, are carefully analysed. The results demonstrated the capability of the proposed algorithm to evaluate the effects of harmonic sources in power networks.

ON OBDD-BASED ALGORITHMS AND PROOF SYSTEMS THAT DYNAMICALLY CHANGE THE ORDER OF VARIABLES

AbstractIn 2004 Atserias, Kolaitis, and Vardi proposed $\text {OBDD}$ -based propositional proof systems that prove unsatisfiability of a CNF formula by deduction of an identically false $\text {OBDD}$ from $\text {OBDD}$ s representing clauses of the initial formula. All $\text {OBDD}$ s in such proofs have the same order of variables. We initiate the study of $\text {OBDD}$ based proof systems that additionally contain a rule that allows changing the order in $\text {OBDD}$ s. At first we consider a proof system $\text {OBDD}(\land , \text{reordering})$ that uses the conjunction (join) rule and the rule that allows changing the order. We exponentially separate this proof system from $\text {OBDD}(\land )$ proof system that uses only the conjunction rule. We prove exponential lower bounds on the size of $\text {OBDD}(\land , \text{reordering})$ refutations of Tseitin formulas and the pigeonhole principle. The first lower bound was previously unknown even for $\text {OBDD}(\land )$ proofs and the second one extends the result of Tveretina et al. from $\text {OBDD}(\land )$ to $\text {OBDD}(\land , \text{reordering})$ .In 2001 Aguirre and Vardi proposed an approach to the propositional satisfiability problem based on $\text {OBDD}$ s and symbolic quantifier elimination (we denote algorithms based on this approach as $\text {OBDD}(\land , \exists )$ algorithms). We augment these algorithms with the operation of reordering of variables and call the new scheme $\text {OBDD}(\land , \exists , \text{reordering})$ algorithms. We notice that there exists an $\text {OBDD}(\land , \exists )$ algorithm that solves satisfiable and unsatisfiable Tseitin formulas in polynomial time (a standard example of a hard system of linear equations over $\mathbb {F}_2$ ), but we show that there are formulas representing systems of linear equations over $\mathbb {F}_2$ that are hard for $\text {OBDD}(\land , \exists , \text{reordering})$ algorithms. Our hard instances are satisfiable formulas representing systems of linear equations over $\mathbb {F}_2$ that correspond to checksum matrices of error correcting codes.

An Efficient and Rapid Numerical Quadrature to generate element matrices for quadrilateral and hexahedral elements in Functionally Graded Materials (FGMs)

This research paper introduces a robust, efficient and stabilized midpoint quadrature to generate element stiffness matrices for quadrilateral and hexahedral elements in finite element method (FEM). This new quadrature is established based on Passive Richardson extrapolation which has the inherent ability to stabilize and improve the accuracy of the extrapolated results. The new quadrature includes a simple artificial stabilizing function with Gauss one-point quadrature (1GP) as an anti-hourglass effect. For the first approximation, the 1GP (sampling point to be considered at origin (0,0)) is done to evaluate element matrices (thermal conductivity matrices, capacitance matrices etc.,) in the 4-square element ( [-2, 2] x [-2, 2] ) in the (ξ, η) plane. As a stabilizing function, sampling points are considered to be either at the center of the four element edges or center of the four quadrants in the reference square element with appropriate constant weighting functions. For hexahedral elements also, the element stiffness coefficients are calculated only in the center of the element and center of all the octants of the reference cubic element ([-2, 2] x [-2, 2] x [-2, 2]), the proposed method deals mostly with integer variables and sampling at (0,0,0), whereas Gauss quadrature uses lengthy float variables corresponding to irrational numbers in terms of decimals in the stiffness matrix calculations, thus consuming time. A number of standard example problems are demonstrated to assess the efficiency of the proposed method. The results of all the numerical examples are found to be in good agreement with the exact results and conventional Gauss quadrature results.

Construction Method of a Guaranteed Grid Considering the Specific Recovery Process

For the planning of the guaranteed power grid, only the operation capacity of the target grid is considered. The recovery process and steps of the backbone grid are not considered enough, which leads to two defects: the minimum guaranteed power grid is not conducive to the unit recovery and the recovery time is too long. In this paper, a method of constructing the grid with the specific recovery process is proposed. Considering the influence of the grid structure and the position of the black start power supply on the recovery steps, the recovery success rate and the recovery time of the grid, the optimization of the grid structure of the guaranteed grid can meet the demand of power supply and at the same time make the recovery of the target grid less time-consuming and achieve a higher recovery success rate in the event of a blackout. In this method, two aspects are considered: the power failure recovery scenario in the recovery process of the target grid and the normal power supply scenario, reflecting the power supply performance after the recovery of the target grid. In the normal power supply scenario, a three-objective optimization model including power supply capacity, smooth transmission and safety margin is constructed, with power supply capacity and safe operation as constraints. In the scenario of power failure recovery, the process of power grid recovery and the mechanism affecting the success of recovery are analyzed to form the line recovery index. The Dijkstra algorithm is used to search for the optimal recovery path and calculate the recovery index, so as to reoptimize the backbone power grid. The validity of the method is verified by standard and practical examples.

Application of Adaptive Phase-Field Scaled Boundary Finite Element Method for Functionally Graded Materials

In this paper, an adaptive phase-field scaled boundary finite element method for fracture in functionally graded material (FGM) is presented. The model accounts for spatial variation in the material and fracture properties. The quadtree decomposition is adopted for refinement, and the refinement is based on an error indicator evaluated directly from the solutions of the scaled boundary finite element method. This combination makes it a suitable choice to study fracture using the phase field method, as it reduces the mesh burden. A few standard benchmark numerical examples are solved to demonstrate the improvement in computational efficiency in terms of the number of degrees of freedom.

The institutionalization of accounting: the impact of national standards on the development of economies

The purpose of the study is to establish the essence and identification of the components of institutional accounting theory and substantiate the role and impact of these components on the national economy through the example of standardization. The author's general scheme of the institutional paradigm of institutional accounting and the approach to the development of his theory was built in the study based on a theoretical, empirical generalization, taking into account positive foreign experience, national scientific views and traditions. The examples of changes in GDP after the introduction of accounting standards (which are a structural component of institutional accounting theory) in the 6 largest countries of the world are given as an argument for the positive impact of institutional pragmatics on the national economy using the graphical method. It is proved that the dynamics that can be used to identify the impact of accounting standardization on a country's economy may be the dynamics of its GDP. The expediency of taking into account the institutional environment of Ukraine in the issues of formalization of the Institute of Accounting, as well as its political, environmental and social situation is substantiated. The conducted research confirms the influence of national peculiarities on the results of activation of institutional accounting principles and the presence of individual characteristics of values taken as arguments of indicators. It is substantiated that it is important to find effective indicators to illustrate the impact of each institutional component of accounting on the national economy.

Book Reviews

Presents a review of the book, "The Cambridge Handbook of Technical Standardization Law: Further Intersect ions of Public and Private Law (Contreras, J.L., Ed.). This book on technical standardization law is one of the more timely books available in this area. It in fact a continuation of the previous book by the same editor covering technical standardization law from the perspective of competition, antitrust, and patents. However, in this volume 2 of the book, the focus is on the intersections of public and private laws with respect to standardization. It surveys how today’s standardization is affected by both the public and private laws across the United States and Europe. This book is useful for researchers, practitioners, post-graduate students, lawyers, judges, policy makers, and most importantly to all those who are involved in communication standardization activities in any capacity. The main feature of this book is that it gives examples of standards that are currently in practice. For instance, throughout the book, the discussion revolves around standardization bodies such as the European Telecommunications Standards Institute (ETSI), the American National Standard Institute (ANSI), the International Standards Organization (ISO), the Internet Engineering Task Force (IETF), the British Standards Institute (BSI), and the International Telecommunications Union (ITU). Additionally, this book covers copyright and trademark issues with respect to communication protocols, standards, and technologies such as HTML, XML, HTTP, Bluetooth, Wi-Fi, and USB. On top of this discussion, one of the unique features of this book is its coverage of open standards and government policies for their adoption, both in the United- States and Europe. Overall, however, this book is a good reference book for courses on telecom policy, cyber ethics and laws, and standardization laws. In simple words, it is important to investigate how international trade law, copyright, trademarks, certifications, and legal frameworks influence private standardization activities, more particularly in the context of the networked economy and broadly in the communications sector.

Damage Detection of Truss Structures by Reduction of Degrees of Freedom Using the Serep Method

Damage detection of bridge structures during their operating lifetime is essential. In this paper, two approaches, All Degrees of Freedom and Reduction of the Degrees of Freedom methods, are used to detect the damages in structures. The first method considers All Degrees of Freedom of the structure and the second method, Reduction of the Degrees of Freedom. Since the sensors are installed only on a few degrees of freedom, the responses are available for some of them. The Degrees of Freedom must be reduced and System Equivalent Reduction Expansion Process method is one of the most efficient ways to solve the problem. This research aimed to identify the damage of structures using the Modal Strain Energy method by reducing the structural degree of freedom. Two standard examples are used and the results compared to different damage cases to examine the efficiency of the mentioned method. The results illustrated the proper performance of the Reduction of the Degrees of Freedom method to identify the damage in truss structures. By increasing the number of modes, Reduction of the Degrees of Freedom method detects considerably more accurate the damaged elements, especially when the noise is considered. Also, based on the outcomes to identify damaged elements, it is possible to consider more modes instead of more sensors.

Untold secrets of the slowly charging capacitor

The slowly charging capacitor is the standard example used to illustrate that the displacement current density is needed in Ampere's law if we want to correctly determine the magnetic field between capacitor plates. However, in any quasi-static situation the magnetic field can also be determined using the Biot-Savart law including only the real current densities. In this work, we will numerically calculate the magnetic field due to the surface currents on the capacitor plates and add it to the magnetic field due to the charging wire and show how they combine to create the correct magnetic field thoughout all space. For regions to the left or right of the capacitor, we find the surprising result that the surface currents replicate the magnetic field that would have been created by the missing section of the charging wire between the plates. For points between the capacitor plates, the magnetic field due to the surface currents mostly cancels the magnetic field from the near-infinite length charging wire, resulting in the well-known reduced field in that interior region. We will also illustrate the impact of finite capacitor plates on these results and briefly comment on how textbook and/or classroom discussions could be improved by carefully discussing these details.

Block Third Derivative Trigonometrically-Fitted Methods for Stiff and Periodic Problems

This article constructed and implemented a family of a third derivative trigonometric fitted method of order k+3 whose coefficients are functions of frequency and step size for the integration of systems of first-order stiff and periodic Initial Value Problems. The Block Third Derivative Trigonometric Fitted methods (BTDTFMs) are constructed via multistep collocation technique and applied in block form as simultaneous numerical integrators which make them self-starting. The convergence, accuracy, and efficiency of the methods are established through some standard numerical examples.

Education of Ho Chi Minh’s Moral Example for Students in Vietnam Nowadays

Ho Chi Minh was one of the thinkers and revolutionary activists who had special interest in morality. In anywhere or at any time, Ho Chi Minh always first spoke and wrote about morality. More importantly, Ho Chi Minh always acted and behaved in accordance with moral standards that he set. Ho Chi Minh not only left a moral ideological system but also an example of the moral standards that he raised. Ho Chi Minh's thought and moral example were not only of great value to revolutionary work of national liberation but in the current period of national development, becoming a solid spiritual foundation of life in Vietnamese society. Vietnamese students are educated youth, a source of high quality labor of society, is generation that continues the legacy of ancestor's revolution. In order to do that, to promote the strength of Vietnamese youth in the work of building and defending the country requires the family, school and society to take care of them and educate them and the formation of revolutionary moral characteristics for students is determined to be fundamental. Ho Chi Minh was the pure embodiment, the most typical of the pure and beautiful moral qualities; therefore, education of Ho Chi Minh's moral example becomes a matter of necessity. In this article, the author focuses on clarifying basic issues, namely: the concept of students and the education of Ho Chi Minh's moral example for students; Ho Chi Minh's moral example and contents of Ho Chi Minh's moral example needed to educate Vietnamese students nowadays. Keywords : education, normal example, Vietnam DOI: 10.7176/RHSS/10-4-12 Publication date: February 29 th 2020

A combined virtual element method and the scaled boundary finite element method for linear elastic fracture mechanics

In this paper, we propose a framework that combines the recently introduced virtual element method (VEM) and the scaled boundary finite element method (SBFEM) to evaluate the fracture parameters. The domain is discretized with arbitrary polygons and the element that contains the crack tip is treated within the framework of the SBFEM. This facilitates a semi-analytical treatment of the crack tip singularity allowing the fracture parameters are estimated directly from the definition. The VEM is employed for the rest of the domain. The salient feature of the VEM is that the terms in the stiffness matrix are computed without requiring higher order quadrature schemes. As both the methods satisfy partition of unity and the compatibility condition, the matrices are assembled as in the conventional FEM. The accuracy of the proposed formulation is demonstrated with two standard benchmark examples. The proposed VEM-SBFEM framework yields accurate results.

A channel-based perspective on conjugate priors

AbstractA desired closure property in Bayesian probability is that an updated posterior distribution be in the same class of distributions – say Gaussians – as the prior distribution. When the updating takes place via a statistical model, one calls the class of prior distributions the ‘conjugate priors’ of the model. This paper gives (1) an abstract formulation of this notion of conjugate prior, using channels, in a graphical language, (2) a simple abstract proof that such conjugate priors yield Bayesian inversions and (3) an extension to multiple updates. The theory is illustrated with several standard examples.

The General Higher-Order Neural Network Model and Its Application to the Archive Retrieval in Modern Guangdong Customs Archives

Because of the unique attributes of archive information, it is challenging to manage and effectively retrieve archive information in the archive information management practice. This paper designs and develops the first general higher-order Neural Network Model for archives. Based on the analysis of the correlation, the relevance of the weight model, the study of technical methods about the core weight, the direction weight retrieval, and the statistical ranking of the results, this paper designs a corresponding archive information analysis system. Finally, this paper adopts the B/S development model by applying the relevance ranking weight algorithm into the comprehensive archive retrieval activities, which not only enhances the intelligence and efficiency of the archive retrieval, but also can act as a standard example to demonstrate informatization construction for archive management. This paper compares this algorithm with two other existing retrieval algorithms and verifies the practicability of the relevance algorithm by evaluating the algorithm and the default retrieval algorithm using the NDCG evaluation method.

A City ősi szívében : Bloomberg Irodaház, London = In the Ancient Heart of the City : Bloomberg Headquarters, London

As an outstanding example of BREEAM standards this office development, comprising of two buildings on a 3.2 hectare site, strives to revitalize the heart of the city. Aside from moving the building cores to the perimeters the inclusion of artworks including Cristina Iglesias’ “Forgotten Streams” assists in the definition of public spaces. The latter idea exaggerated by the central Vortex, use of curved timber shells and glazed lifts. The overall intention is to animate space and increase the chance of meetings and informal discussion.

QoS-Constrained Service Selection for Networked Microservices

In the microservice system, microservices are generally deployed as many microservice instances connected by a network system, and there are several composite services (CSs) in the system, each of which consists of several tasks that need to be executed on instances and has some Quality of Service (QoS) constraints to represent the user requirement for QoS. At runtime, it is necessary to select the microservice instance for each task under constraints and form an execution path of the CS. However, traditional service selection methods focus on the QoS optimization of a single CS, while ignoring sharing and competition of instances. To address this problem, this paper presents a Microservice Service Selection algorithm (MSS) based on list scheduling. Firstly, a workflow model is employed to describe the CS and to analyze the processing speed of instances, the transferring speed of the network and the degree of task concurrency, to calculate the sub-deadline of each task. Then, according to the sub-deadline and other information, the scheduling urgency of each task is calculated and updated in real-time. Finally, two service selection strategies based on the sub-deadline and urgency are proposed to complete the microservice instances selection and constitute the service path. Experiments have been carried out using the standard workflow examples of real-world applications. The results show that the proposed selection strategies can effectively improve the performance of service selection in network systems.

Case Article—Workforce Scheduling for Airport Immigration on the Island of Tropical Paradise

This case study focuses on modeling and analyzing the practices concerning the staffing of the immigration agency at the Island of Tropical Paradise International Airport, which is responsible for processing arriving passengers into the country. Students are challenged to model the status quo of immigration employee scheduling and analyze various high-level policy changes to determine the reduction in staffing requirements while also being concerned with the wait time of passengers in the queue at immigration. The case has been used in an introductory operations research (OR) course in an engineering curriculum as a term project and was created based on a client of a major consulting organization. The main teaching objective of the case is to have students demonstrate an understanding of how to use OR models and analysis to impact practice. To this end, the case moves the students from standard classroom or textbook examples to an open-ended problem where there is not a single correct model or analysis to tackle it.

The rigidity and stability of complete 𝑓-minimal hypersurfaces in ℝⁿ×𝕊¹(𝕒)

In this paper we consider f f -minimal hypersurfaces in the product space R n × S 1 ( a ) \mathbb {R}^n \times \mathbb {S}^1(a) where ( R n , e − f d μ ) (\mathbb {R}^n,e^{-f}d\mu ) is the standard Gaussian space with d μ d\mu being the standard volume element on R n \mathbb {R}^n . By introducing a globally defined smooth function α \alpha , we shall derive some interesting differential identities by which we are able to prove several rigidity theorems. We also study the stability properties of some standard examples. As a result, we prove that R n × { s 0 } ↪ R n × S 1 ( a ) \mathbb {R}^n \times \{s_0\} \hookrightarrow \mathbb {R}^n \times \mathbb {S}^1(a) is the only complete, proper, and stable f f -minimal hypersurface.