Introduction

The topic chosen for the next four items seems to suggest itself and to be undeniably exciting for any science student: the future of science — what is it likely to be? And who are more competent to make forecasts than scientists themselves? So the aim in this part is to give an opportunity for two prominent scientists, representing two major sciences - physics and molecular biology, to present the respective cases for their chosen fields of research, to point out tendencies, and to forecast foreseeable future. As these two fields are known to be in the forefront of the search for knowledge, their future development will certainly have a direct bearing on the future of science as a whole. The contribu­tors are the Nobel Laureate Francis Crick and Professor Freeman Dyson, whose views are presented in the following items: A. Physics: Its Recent Past and the Lessons to be Learned. B. Molecular Biology in the Year 2000. C. Physics in the Next 30 Years. D. Forecasts in Science: Are They Worth Making?

Task 12. Here is an abstract from a published paper. It is 220 words long. Read it through looking for the main purpose of each sentence (for example, presenting research problem, objective, methodology, main findings, or conclusion).

Abstract Major problems of the arid region are transportation of agricultural products and losses due to spoilage of the products, especially in summer. This work presents the performance of a solar drying system consisting of an air heater and a dryer chamber connected to a greenhouse. The drying system is designed to dry a variety of agricultural products. The effect of air mass flow rate on the drying process is studied. Composite pebbles, which are constructed from cement and sand, are used to store energy for night operation. The pebbles are placed at the bottom of the drying chamber and are charged during the drying process itself. A separate test is done using a simulator, a packed bed storage unit, to find the thermal characteristics of the pebbles during charging and discharging modes with time. Accordingly, the packed bed is analyzed using a heat transfer model with finite difference technique described before and during the charging and discharging processes. Graphs are presented that depict the thermal characteristics and performance of the pebble beds and the drying patterns of different agricultural products. The results show that the amount of energy stored in the pebbles depends on the air mass flow rate, the inlet air temperature, and the properties of the storage materials. The composite pebbles can be used efficiently as storing media.

This sentence gives the general problem the research is attempting to help solve (rather than the specific research problem) in order to provide a rationale for the research.

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This part of the abstract gives the main objective of the research.

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Here the authors give the parameter they will be focusing on in order to measure the effect of air mass flow rate on the drying process. Their research problem, therefore, is to find out the effect of air mass flow rate on the drying process. 

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This part of the abstract summarizes the methodology used.

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Here we are told in what form the results are presented, and the main findings.

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Finally, we are presented with the main conclusion of the research. 

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Haralambopoulos, D., Paparsenost, G. F., and Kovras, H. (1997) Assessing the Economic Aspects of Solar Hot Water Production in Greece. Renewable Energy, 11, 153-167.

(Adopted from http://www.languages.ait.ac.th/el21abst.ht)

Task 13. Here is the second abstract from a published paper. It is 162 words long. Again, read it through looking for the main purpose of each sentence (for example, presenting the research problem, objective, methodology, main finding, or conclusion). You can find suggested answers lower.

Abstract The long-term performance of various systems was determined and the economic aspects of solar hot water production were investigated in this work. The effect of the collector inclination angle, collector area and storage volume was examined for all systems, and various climatic conditions and their payback period was calculated. It was found that the collector inclination angle does not have a significant effect on system performance. Large collector areas have a diminishing effect on the system’s overall efficiency. The increase in storage volume has a detrimental effect for small daily load volumes, but a beneficial one when there is a large daily consumption. Solar energy was found to be truly competitive when the conventional fuel being substituted is electricity, and it should not replace diesel oil on pure economic grounds. Large daily load volumes and large collector areas are in general associated with shorter payback periods. Overall, the systems are oversized and are economically suitable for large daily hot water load volumes.

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Helwa, N. H. and Abdel Rehim, Z. S. (1997). Experimental Study of the Performance of Solar Dryers with Pebble Beds. Energy Sources, 19, 579-591.

(Adapted from http://www.languages.ait.ac.th/el21abst.ht)  

Task 14. Now read texts A and B (one of them is an abstract, another - an introduction. The title of the article is «Approximate Distributed K-Means clustering over a Peer-to-Peer Network» by Souptik Datta, Chris R. Giannella, and Hillol Kargupta, Senior Member, IEEE), then answer the question: which of these two texts is an «abstract» and which is an «introduction».

Text A

Data intensive Peer-to-Peer (P2P) networks are finding increasing number of applications. Data mining in such P2P environments is a natural extension. However, common monolithic data mining architectures do not fit well in such environments since they typically require centralizing the distributed data which is usually not practical in a large P2P network. Distributed data ining algorithms that avoid large-scale synchronization or data centralization offer an alternate choice. This paper considers the distributed K-means clustering problem where the data and computing resources are distributed over a large P2P network. It offers two algorithms which produce an approximation of the result produced by the standard centralized K-means clustering algorithm. The first is designed to operate in a dynamic P2P network that can produce clustering by “local” synchronization only. The second algorithm uses uniformly sampled peers and provides analytical guarantees regarding the accuracy of clustering on a P2P network. Empirical results show that both the algorithms demonstrate good performance compared to their centralized counterparts at the modest communication cost. Index Terms—Peer-to-peer data mining, distributed K-means clustering.

(http://www2.computer.org/portal/c/document_library/get_file)

Text B

K-MEANS clustering is a well-known and well-studied exploratory data analysis technique. The standard version assumes that all data are available at a single location. However, if data sources are distributed over a large-scale Peer-to-Peer (P2P) network, collecting the data at a central location before clustering is not an attractive and practical option. There exist many important and exciting applications of K-means clustering on data distributed over a P2P network, and for these, a highly scalable, communication- efficient, distributed algorithm is desired. This paper proposes two such algorithms for K-means clustering on data distributed over a P2P network. The first algorithm takes a completely decentralized approach, where peers (nodes) only synchronize with their immediate topological neighbors in the underlying communication network.1 This algorithm can easily adapt to dynamic P2P network where existing nodes drop out and new nodes join in during the execution of the algorithm and the data in network changes. However, it is difficult to analyze that the algorithm and performance guarantees are experimentally verified. Our experiments show that the algorithm converges quickly, and the accuracy is quite good and resilient to changes in network topology. Our second algorithm works by taking uniform random samples of nodes from the network. We provide analytical bounds on the accuracy of its clustering results in addition to empirical verification. The paper is organized as follows: Section 2 describes motivational application to emphasize the need for distributed clustering algorithm in P2P network. Section 3 briefly describes the related work in clustering in distributed environments. Section 4 formally defines the problem that this paper addresses along with the notations. Section 5 describes our first approach, a local synchronization-based K-means algorithm. Section 6 describes the experimental setup (simulator and data generator) and the results of our first algorithm. Section 7 describes our second approach, a uniform sampling-based algorithm. Sections 8 and 9 describe the corresponding experimental results. Finally, Section 10 concludes the paper.

(http://www2.computer.org/portal/c/document_library/get_file)

Task 15. Read text A «The Biosphere: Its Definition, Evolution and Possible Future» and write the abstract to it.