Chapter 21. Combinatorial Designs by SAT Solvers1

Author(s):  
Hantao Zhang

The theory of combinatorial designs has always been a rich source of structured, parametrized families of SAT instances. On one hand, design theory provides interesting problems for testing various SAT solvers; on the other hand, high-performance SAT solvers provide an alternative tool for attacking open problems in design theory, simply by encoding problems as propositional formulas, and then searching for their models using off-the-shelf general purpose SAT solvers. This chapter presents several case studies of using SAT solvers to solve hard design theory problems, including quasigroup problems, Ramsey numbers, Van der Waerden numbers, covering arrays, Steiner systems, and Mendelsohn designs. It is shown that over a hundred of previously-open design theory problems were solved by SAT solvers, thus demonstrating the significant power of modern SAT solvers. Moreover, the chapter provides a list of 30 open design theory problems for the developers of SAT solvers to test their new ideas and weapons.

10.37236/791 ◽  
2008 ◽  
Vol 15 (1) ◽  
Author(s):  
Paweł Prałat

In this paper, we consider the on-line Ramsey numbers $\overline{\cal R} (k,l)$ for cliques. Using a high performance computing networks, we 'calculated' that $\overline{\cal R}(3,4)=17$. We also present an upper bound of $\overline{\cal R}(k,l)$, study its asymptotic behaviour, and state some open problems.


2014 ◽  
Vol 36 (4) ◽  
pp. 790-798
Author(s):  
Kai ZHANG ◽  
Shu-Ming CHEN ◽  
Yao-Hua WANG ◽  
Xi NING

2011 ◽  
Vol 28 (1) ◽  
pp. 1-14 ◽  
Author(s):  
W. van Straten ◽  
M. Bailes

Abstractdspsr is a high-performance, open-source, object-oriented, digital signal processing software library and application suite for use in radio pulsar astronomy. Written primarily in C++, the library implements an extensive range of modular algorithms that can optionally exploit both multiple-core processors and general-purpose graphics processing units. After over a decade of research and development, dspsr is now stable and in widespread use in the community. This paper presents a detailed description of its functionality, justification of major design decisions, analysis of phase-coherent dispersion removal algorithms, and demonstration of performance on some contemporary microprocessor architectures.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fan Qi ◽  
Zhang Chaoqun ◽  
Yang Weijun ◽  
Wang Qingwen ◽  
Ou Rongxian

Abstract On the basis of the world’s continuing consumption of raw materials, there was an urgent need to seek sustainable resources. Lignin, the second naturally abundant biomass, accounts for 15–35% of the cell walls of terrestrial plants and is considered waste for low-cost applications such as thermal and electricity generation. The impressive characteristics of lignin, such as its high abundance, low density, biodegradability, antioxidation, antibacterial capability, and its CO2 neutrality and enhancement, render it an ideal candidate for developing new polymer/composite materials. In past decades, considerable works have been conducted to effectively utilize waste lignin as a component in polymer matrices for the production of high-performance lignin-based polymers. This chapter is intended to provide an overview of the recent advances and challenges involving lignin-based polymers utilizing lignin macromonomer and its derived monolignols. These lignin-based polymers include phenol resins, polyurethane resins, polyester resins, epoxy resins, etc. The structural characteristics and functions of lignin-based polymers are discussed in each section. In addition, we also try to divide various lignin reinforced polymer composites into different polymer matrices, which can be separated into thermoplastics, rubber, and thermosets composites. This chapter is expected to increase the interest of researchers worldwide in lignin-based polymers and develop new ideas in this field.


2003 ◽  
Vol 12 (5-6) ◽  
pp. 653-660
Author(s):  
C. C. Rousseau ◽  
S. E. Speed

Given a graph Hwith no isolates, the (generalized) mixed Ramsey number is the smallest integer r such that every H-free graph of order r contains an m-element irredundant set. We consider some questions concerning the asymptotic behaviour of this number (i) with H fixed and , (ii) with m fixed and a sequence of dense graphs, in particular for the sequence . Open problems are mentioned throughout the paper.


Author(s):  
Sheng Kang ◽  
Guofeng Chen ◽  
Chun Wang ◽  
Ruiquan Ding ◽  
Jiajun Zhang ◽  
...  

With the advent of big data and cloud computing solutions, enterprise demand for servers is increasing. There is especially high growth for Intel based x86 server platforms. Today’s datacenters are in constant pursuit of high performance/high availability computing solutions coupled with low power consumption and low heat generation and the ability to manage all of this through advanced telemetry data gathering. This paper showcases one such solution of an updated rack and server architecture that promises such improvements. The ability to manage server and data center power consumption and cooling more completely is critical in effectively managing datacenter costs and reducing the PUE in the data center. Traditional Intel based 1U and 2U form factor servers have existed in the data center for decades. These general purpose x86 server designs by the major OEM’s are, for all practical purposes, very similar in their power consumption and thermal output. Power supplies and thermal designs for server in the past have not been optimized for high efficiency. In addition, IT managers need to know more information about servers in order to optimize data center cooling and power use, an improved server/rack design needs to be built to take advantage of more efficient power supplies or PDU’s and more efficient means of cooling server compute resources than from traditional internal server fans. This is the constant pursuit of corporations looking at new ways to improving efficiency and gaining a competitive advantage. A new way to optimize power consumption and improve cooling is a complete redesign of the traditional server rack. Extracting internal server power supplies and server fans and centralizing these within the rack aims to achieve this goal. This type of design achieves an entirely new low power target by utilizing centralized, high efficiency PDU’s that power all servers within the rack. Cooling is improved by also utilizing large efficient rack based fans for airflow to all servers. Also, opening up the server design is to allow greater airflow across server components for improved cooling. This centralized power supply breaks through the traditional server power limits. Rack based PDU’s can adjust the power efficiency to a more optimum point. Combine this with the use of online + offline modes within one single power supply. Cold backup makes data center power to achieve optimal power efficiency. In addition, unifying the mechanical structure and thermal definitions within the rack solution for server cooling and PSU information allows IT to collect all server power and thermal information centrally for improved ease in analyzing and processing.


2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Mouna Baklouti ◽  
Mohamed Abid

To meet the high performance demands of embedded multimedia applications, embedded systems are integrating multiple processing units. However, they are mostly based on custom-logic design methodology. Designing parallel multicore systems using available standards intellectual properties yet maintaining high performance is also a challenging issue. Softcore processors and field programmable gate arrays (FPGAs) are a cheap and fast option to develop and test such systems. This paper describes a FPGA-based design methodology to implement a rapid prototype of parametric multicore systems. A study of the viability of making the SoC using the NIOS II soft-processor core from Altera is also presented. The NIOS II features a general-purpose RISC CPU architecture designed to address a wide range of applications. The performance of the implemented architecture is discussed, and also some parallel applications are used for testing speedup and efficiency of the system. Experimental results demonstrate the performance of the proposed multicore system, which achieves better speedup than the GPU (29.5% faster for the FIR filter and 23.6% faster for the matrix-matrix multiplication).


2014 ◽  
Vol 596 ◽  
pp. 276-279
Author(s):  
Xiao Hui Pan

Graph component labeling, which is a subset of the general graph coloring problem, is a computationally expensive operation in many important applications and simulations. A number of data-parallel algorithmic variations to the component labeling problem are possible and we explore their use with general purpose graphical processing units (GPGPUs) and with the CUDA GPU programming language. We discuss implementation issues and performance results on CPUs and GPUs using CUDA. We evaluated our system with real-world graphs. We show how to consider different architectural features of the GPU and the host CPUs and achieve high performance.


2015 ◽  
Author(s):  
Peter G. Noble

By looking backwards we can often discover solutions that will allow forward progress. We see in the bible the idea that history repeats itself: What has been will be again, what has been done will be done again; there is nothing new under the sun. Ecclesiastes 1:9 But the author subscribes to the idea put forward by the American humorist, Mark Twain: History doesn’t repeat itself, but sometimes it rhymes. The design and construction of water-borne craft using “scientific” methods is a relatively recent development in the context of the whole history of that activity, and is by no means universally applied even today Many traditional craft in current service still rely on the process akin to natural selection, as proposed by Darwin, that is, it is not the strongest, most intelligent nor the fittest that survive but those that best adapt. And the evolutionary process continues today. From Bangkok water taxis with “long-tail” propulsion systems, and from Haitian fishing boats with high performance new sails to whaling umiaks in NW Alaska covered with tensioned membrane skins made from walrus hide and equipped with outboard motors, there can be value in studying the design, construction and operational approaches of these craft. Such consideration can lead to insights for the modern naval architect. A number of well-researched publications (Tapan Adney, 1964) and (Haddon, 1975) give a wealth of information on indigenous craft. Sturgeon Nose Canoe USN ZUMWALT Class Destroyer. Noble Lessons to be learned from the study of indigenous craft 2 Lessons such as optimizing weight/strength ratios, minimizing resistance, utilizing materials in clever ways, developing repairable structures etc., can all be learned from the study of indigenous craft. The sense of continuity with a living past obtained by the study of the work of previous generations of designers and builders, realizing that many current problems were their problems too, is both valuable and satisfying. That said, not all examples given in this paper can be directly linked to designers actively seeking out past developments. Some examples have occurred by coincidence, some by accident and some by unwitting “reinvention of the wheel”. Many “new” ideas, however, have been tried before and it is very often possible to test a new idea against past experience. This paper builds on previous ethno-technical study, (Noble 1994) describing the author’s experience in this field and uses a number of specific examples to illustrate the premise.


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