Technology for searching information on the Internet: Internet information search systems. To make a decision in each specific situation, a specialist needs to obtain the most complete and up-to-date information relevant to a given case. Search by k

Video tutorial: How to create queries in Microsoft Access in 10 minutes

Lecture: Using search engine tools (forming queries)

The most important functions when working with databases are information filter, search and query.

Sorting is the process of organizing information according to some criteria. There is ascending and descending sorting. If the database has numerical information, then ranking is used as sorting, and if we are talking about text information, then alphabetical sorting is used.

When considering sorting by database management systems in MS Access sorting carried out within one field. If a new sort is used, its previous results are lost. If the sorting is nested, then you can perform it using a query.

Filter– this is the selection of information necessary for the user. You can set complex selection conditions.

To find some data, you can use special characters called mask:

* – means that you can select any number of characters.

? – instead of this sign there can be any symbol that can be used.

# – this symbol can be replaced by any number.

– any characters in brackets.

- – any symbol corresponding to the selected range.

! – any character except those enclosed in square brackets.

This character filter can be used for the entire table, or for a part of the data already selected by certain criteria.

Request– this function is large-scale and can include both sorting and filtering. This function allows you to select data in several fields and tables. You can create a library of queries that are saved for future use. There is a special language SQL queries– structured.

Placement of information resources.

Information resource search tools.

Currently, Internet information resources are growing at a rapid pace. World Wide Web resembles a library reading room, where gigantic volumes of text, graphics, multimedia, archival and other files are stored. It is impossible to completely bypass this room. Here everything changes hourly, the body of various documents grows every second. Find necessary information It's getting more and more difficult. Various printed reference books become outdated even before they are published. The only reliable way to search for information is to use special search engines that constantly monitor changes in information on the Internet.

Resources used on the Internet are most often located on the pages of WWW servers (or Web servers), in file archives (FTP archives) and in the Gopher information and reference system.

WWW (World Wide Web) is a global hypertext system that uses the HTTP (HyperText Transfer protocol) protocol to transport information on the Internet. Hypertext is a way of representing all types of information as a sequence of nodes connected to each other by an associative (rather than sequential) connection and implemented in the form of hyperlinks. Hyperlink is a sequence of characters highlighted in hypertext that responds to a mouse click and sends the user to another fragment of hypertext. Most documents stored on a Web server are created in HTML language(HyperText Markup Language - hypertext markup language for documents).

A Gopher server is a server that contains programs that allow you to find files, programs, or other resources on a user-specified topic. The URL of such a server looks like this (if the server, for example, belongs to Microsoft): gopher://gopher.microsoft.com.

There are two groups of search tools: 1) search engines and 2) search services.

IRS (information retrieval system) – This is a system that provides search and selection of necessary data in a special database with descriptions of information sources ( index ) based on information retrieval language and corresponding search rules.

On the Internet, the following search tools for the WWW can be distinguished: search engines, metasearch engines (search services) and accelerated search programs (search agents).

Fig. 13. WWW search tools

Depending on who creates the databases in which the information needed by the user is searched, there are search engines of the first and second kind. In search engines of the first type, databases are created by people; in search engines of the second type, this process is carried out by a computer.

Search engines of the first kind are usually called catalogs (subject or thematic - subject catalogs). Typically, such directories are created by people in the form of hierarchical trees, on upper level which are worth the most general concepts: business, politics, education, sports, culture, etc. The lower level elements of such trees are links to specific Web pages and servers. Typically, a search in subject catalogs is carried out by keywords. In this case, it is carried out not in the content of the Web servers, but in their brief descriptions stored in the directory. A search request is formed either as a list of keywords (“information technology”, “computer linguisics”, etc.) or by specifying the URLs of the documents to be searched. Search results are presented in the form of hypertext containing as hypertext links titles or URLs of the documents found.

You can search for the following information using keywords:

1) some text or part of it;

2) factual data (for example, the mass of the sun or the name of the president of the country);

3) paintings, drawings, films, etc. by their names;

4) technical information(for example, information about the speed of a certain car);

5) biographies of people (writers, artists, etc.).

Examples of thematic directories are Yahoo, Galaxy, WWW Virtual Library, WebCrawler, HotBot, etc. A similar Russian-language system is called “Pathfinder”.

Search engines of the second kind are sometimes called automatic indexes, "spiders" or "worms" spiders, crawlers). They constantly scan the Internet, find new documents on the network, and from each document extract all the hyperlinks it contains, which they use to supplement their databases (URL address databases). To be able to perform these functions, the automatic index includes the following three parts: a robot program that constantly crawls the Internet; a database (multiple URLs) that is collected by the robot, and a user interface for searching the required information in this database. There are a large number of automatic indexes. The most popular are:

Foreign search engines:

- Altavista (http://www.altavista.com);

- Go (Infoseek) (http://www.go.com);

- Google (http://www.google.com);

- Excite (http://www.excite.com);

- HotBot (http://www.hotbot.com);

- Northern Light (http://www.northernlight.com).

Russian search engines:

- Yandex(http://www.yandex.ru);

- Rambler (http://www.rambler.ru);

- Aport (http://www.aport.ru).
Popular Belarusian search engines:

- System ALL.BY (http://all.by);

- System *.BY (http://search.promedia.minsk.by);

- Register of Belarusian WWW resources Zubr (http://www.zubr.com);

- Belarusian Internet catalog Akavita (http://akavita.kryvia.net);

- Belarusian resources catalog (http://www.belresource.com.by),

Most search engines are one of the components of multifunctional Internet Web sites - the so-called portals.

Portal– a multifunctional Internet Web site offering a variety of services: information search, free Email etc.

Lately Systems began to appear on the World Wide Web that automatically search in two indexes at once (the catalog index and the search engine index). Similar systems allow you to take advantage of both types of search engines and are called catalog machines.

Searching for information using various search tools can be carried out by forming simple and complex queries. A simple query is a word or phrase that is sometimes enclosed in quotation marks. A complex query is formed from words or phrases connected by operators such as AND, OR, NOT, NEAR or mathematical symbols, for example "*", "+", "-", "~". Sometimes special terms are used for the same purposes domain, host, link tide and etc.

Search tools

Search tools are special software whose main purpose is to provide the most optimal and high-quality information search for Internet users. Search tools are hosted on special web servers, each of which performs a specific function:

1. Analysis of web pages and entering the analysis results to one or another level of the search server database.

2. Search for information based on the user's request.

3. Providing a convenient interface for searching information and viewing the search result by the user.

The working techniques used when working with one or another search tool are almost the same. Before we discuss them, let's consider the following concepts:

1. The search tool interface is presented in the form of a page with hyperlinks, a query line (search line) and query activation tools.

2. Search engine index is information base, containing the result of analysis of web pages, compiled according to certain rules.

3. A query is a keyword or phrase that the user enters into the search bar. To form various queries, special characters ("", ~), and mathematical symbols (*, +, ?) are used.

The information search scheme is simple. The user types a key phrase and activates the search, thereby receiving a selection of documents based on the formulated (specified) request. This list of documents is ranked according to certain criteria so that at the top of the list are those documents that most closely match the user's request. Each of the search tools uses different criteria for ranking documents, both when analyzing search results and when creating an index (populating an index database of web pages).

Thus, if you specify a query of the same design in the search bar for each search tool, you can get different search results. For the user it has great importance, which documents will appear in the first two to three dozen documents in the search results and how well these documents meet the user’s expectations.

Most search tools offer two search methods − simple search(simple search) and advanced search(advanced search) with or without a special request form. Let's consider both types of search using the example of an English-language search engine.

For example, AltaVista is convenient to use for arbitrary requests, “Something about online degrees in information technology,” while Yahoo's search tool allows you to get world news, exchange rate information or weather forecasts.

Table 1

A simple request gives a certain number of links to documents, because... the list includes documents containing one of the words entered during the request, or a simple phrase (see Table 1). The and operator allows you to specify that all keywords should be included in the document content. However, the number of documents may still be large and reviewing them will take quite some time. Therefore, in some cases it is much more convenient to use the context operator near, which indicates that the words should be located in sufficient proximity in the document. Using near significantly reduces the number of documents found. The presence of the "*" character in the query string means that the word will be searched by its mask. For example, we will get a list of documents containing words starting with “gov” if we write “gov*” in the query string. These could be the words government, governor, etc.

The most developed search service for Russian-language information is provided by the Yandex search server. In Yandex, you can simply write a phrase in Russian that describes what you want to find, and the system will analyze and process your request, and then try to find everything that relates to the given topic. Using special operators, you can create a string that explains to the search engine what your requirements should be for the information you are interested in.

The equally popular search engine Rambler keeps statistics on link traffic from its own database; the same logical operators AND, OR, NOT, the metasymbol * (similar to the * character in AltaVista that expands the query range), coefficient symbols + and - are supported to increase or decrease the significance words entered into the request.

Let's look at the most popular technologies for searching information on the Internet.

Search technologies

Laws of friction and heat and mass transfer in a turbulent boundary layer

There are several types of representation of the “law of friction” (for the reference case), leading to almost identical results. In accordance with the concept of a “logarithmic” boundary layer (at the value of the first turbulence constant χ = 0.4) the friction law for extremely developed turbulence with “vanishing viscosity” is well approximated by the simple Karman formula:

For a power-law representation of the velocity profile, the following formula should be proposed:

Where: ; n– power exponent of the velocity profile;

– semi-empirical coefficient;

A– empirical coefficient;

δ – thickness of the boundary layer.

Using relations for Reynolds numbers built on different linear quantities:

It is important to note that for the case of development of a turbulent boundary layer from the leading edge ( x cr = 0) the law of friction should also be presented in the form:

The values of the parametric quantities of the presented formulas for various speed profiles are summarized in the table

Parameter	n
1/7	1/8	1/9	1/10
A	8,74	9,71	10,6	11,5
	0,0975	0,089	0,0818	0,0757
	1,28	1,25	1,22	1,20
m	0,250	0,222	0,200	0,182
B	0,0252	0,0206	0,0190	0,0148
m 1	0,200	0,182	0,167	0,154
B 1	0,0576	0,0450	0,0362	0,0308

Other forms of representing the law of friction are also known and used, leading to almost the same results. So V.M. Ievlev proposed an approximation:

Formulas for the laws of heat and mass transfer are obtained from the “laws of friction” for standard conditions (reference case) using the well-known principle of Reynolds' triple analogy.

Where: S– correction factor – Reynolds analogy factor for non-compliance with the conditions of the standard (and), factor S as a first approximation, it is satisfactorily approximated by the relation:

It is important to note that in the case of using integral parameters, the “laws” of heat and mass transfer are well described by the dependencies:

Web technology World Wide Web (WWW) is considered a special technology for preparing and posting documents on the Internet. The WWW includes both web pages and digital libraries, catalogues, and even virtual museums! With such an abundance of information, the question arises: “How to navigate in such a huge and large-scale information space -” Search tools come to the rescue in solving this problem.

Search tools are special software whose main purpose is to provide the most optimal and high-quality search for information for Internet users. Search tools are hosted on special web servers, each of which performs a specific function:

1. Analysis of web pages and entering the analysis results to one or another level of the search server database.

2. Search for information based on the user's request.

3. Providing a convenient interface for searching information and viewing search results by the user.

The working techniques used when working with one or another search tool are almost the same. Before we discuss them, let's consider the following concepts:

1. The search tool interface is presented in the form of a page with hyperlinks, a query line (search line) and query activation tools.

2. Search engine index - an information base containing the result of analysis of web pages, compiled according to certain rules.

3. Query - a keyword or phrase that the user enters into the search bar. To form various queries, special characters ("", ~), and mathematical symbols (*, +, -) are used.

However, if you specify a query of the same design in the search bar for each search tool, you can get different search results. It is of great importance for the user which documents will appear in the first two to three dozen documents in the search results and how well these documents correspond to the user’s expectations.

For example, AltaVista is convenient to use for arbitrary queries, ʼʼSomething about online degrees in information technologyʼʼ, while Yahoo's search tool allows you to get world news, information about exchange rates or weather forecasts.

Mastering query refinement criteria and advanced search techniques allows you to increase search efficiency and quickly find the necessary information. First of all, you can increase the efficiency of your search by using logical operators (operations) Or, And, Near, Not, mathematical and special symbols in your queries. Using operators and/or symbols, the user associates keywords in the required sequence to obtain the most appropriate search result for the query. A simple query does not give a large number of links to documents, because the list includes documents containing one of the words entered during the request, or a simple phrase (see Table 1). The and operator allows you to indicate that all keywords should be included in the content of the document. However, the number of documents must still be large and reviewing them will take quite some time. For this reason, in some cases it is much more convenient to use the context operator near, which indicates that the words should be located in sufficient proximity in the document. Using near significantly reduces the number of documents found. The presence of the "*" character in the query string means that the word will be searched by its mask. For example, we will get a list of documents containing words starting with “gov” if we write “gov*” in the query string. These are the words government, governor, etc.

The no less popular search engine Rambler keeps statistics on link traffic from its own database; the same logical operators AND, OR, NOT, the metasymbol * (similar to the character * in AltaVista that expands the query range), coefficient symbols + and - are supported, to increase or reducing the significance of the words entered into the query.

Let's look at the most popular technologies for searching information on the Internet.

Topic 3 Working with Internet search engines

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Plan

Introduction
Search directories
Information retrieval technology

Search engines
Collections of links
Address databases

Conclusion
Bibliography

Introduction

Today, the Internet connects many different networks, millions of computers, about 300 million users on all continents and, according to various estimates, the number of such users is increasing by 15-80% annually. There are two main directions in using the Internet in business. This is quick access to truly vast treasure troves of information on any topic (on hundreds of thousands information servers), search and interactive communication with partners in almost any specialization and geographic location. How to navigate such a large-scale information space? There are specialized search servers for this. They can be divided into thematic directories, index robots (search engines), and meta search systems.

information internet search catalog

Search directories

The main task of the internet is to provide the necessary information. To find the information you need, you need to know the address of the Web page on which this information is located. It is best to search the Internet for the necessary information using search engines. A search engine is a specialized Web site. Search engines are classified by search methods.

Search directories are designed to search by topic. They are usually built on a hierarchical principle, i.e. Each search step involves selecting a subsection with a more specific topic of the information you are looking for. At the lowest level of search, the user receives a relatively small list of links to the information he is looking for.

The Internet Resources Directory is a constantly updated and expanded hierarchical directory containing many categories and individual web servers with a brief description of their contents. The catalog search method involves “moving down the steps,” that is, moving from more general categories to more specific ones. One of the advantages of thematic directories is that the explanations for the links are given by the creators of the directory and fully reflect its content, that is, it gives you the opportunity to more accurately determine how well the content of the server corresponds to the purpose of your search.

An example of a thematic Russian-language catalog is the resource http://www.ulitka.ru/.

On home page This site contains a thematic rubricator, with the help of which the user finds himself in a category with links to products of interest to him. In addition, some thematic directories allow you to search by keywords. The user enters the required keyword into the search bar and receives a list of links with descriptions of sites that most closely match his query. It is worth noting that this search does not occur in the content of WWW servers, but in their brief description, stored in the directory.

The thematic catalog is recognized as the most popular all over the world Yahoo!(http://www.yahoo.com). It is a huge database of URLs for websites on a wide variety of topics. Yahoo! invites you to use a hierarchical tree when searching for information. Those. First, you select a general topic that satisfies the request for information, and then you specify it, following the prompts of the catalog. As a final result, you receive a list of sites containing information that matches your request. On Yahoo! you can also go the other way. Analyze the expected content of the requested information and select keywords that will definitely appear in the materials you are interested in or in their titles. Type these words separated by a space in the input line on the main page Yahoo! and press Enter. The system will try to select the information you are interested in. Because Yahoo! Since the system is English, it is quite convenient to use an Internet translator, such as "Socrates Internet"(http://www.arsenal.ru).

If you are looking for information that is obviously Russian, then it makes sense to use Russian and local Belarusian catalogs. The principle of working with them is identical to the one we examined in the example with Yahoo!. It is worth noting here the first Russian catalog Russia on the Net(http://www.ru), one of the largest Russian-language catalogs List.RU(http://www.list.ru/), Russian version Yahoo!(http://www.yahoo.ru). There is also a catalog "Constellation Internet" containing only selected (declared as the most interesting) resources. Among the Belarusian catalogues, it is worth noting our national Yahoo!(http://unclesam.hypermart.net), a new fast-growing service 09(http://www.09.open.by), server Unibel(http://www.unibel.by) and a small non-searchable database Data(http://www.data.minsk.by). Speaking about databases, one cannot help but recall the wonderful Russian project Internet Yellow Pages(http://www.piter-press.ru/yp), where, as in the book of the same name, it is presented detailed information about a variety of Internet resources.

Business will also need business catalogs and catalogs of goods and services. Perhaps the largest catalog of CIS companies is Partner (http://trifle.net/cis).

Information retrieval technology

The Internet is growing at a gigantic pace and finding the information needed by a specific user is not very easy. But it is possible, since there are resources on the Internet that will help both beginners and professionals not to drown in the ocean of information.

Appearance world wide web The World Wide Web has become a quantitative and qualitative leap in the field information technologies. The number of new resources and the amount of information they contain is growing like an avalanche; the number of needles in the information “haystack” and, accordingly, the size of it itself are increasing. To search for information on the Internet, the following types of resources are available:

- information portals;

- catalogs of Internet resources;

- search engines.

The Internet itself has gradually turned into a Mass Media with a huge audience of users all over the world and an incredible amount of information. It has become a global means of information, entangling the entire globe with communication channels, but it has not absorbed the media we are used to; they have organically joined the network as independent information resources. Almost every newspaper, radio station or TV channel in any country in the world has its own representation on the Internet.

The electronic version of a newspaper can and, as a rule, differs greatly from the paper version, significantly exceeding it in volume - the format of data published on Internet sites is more flexible, it is not limited to pages, newspaper and magazine columns allocated for the material. An element of interactivity appears - readers can leave their comments and reviews about the article they read, news, or analytical review.

Some periodicals, such as TIMES, have even digitized the newspaper's archives throughout its entire existence, including years before computers or computer networks However, searching through such archives is paid and quite expensive.

The most authoritative and professional source of operational information for Internet users and the media are Web resources news agencies. Possessing a wide correspondent network, they disseminate socio-political, economic, scientific and financial information daily and hourly on the Internet and via electronic communication channels.

Search tools

1. Analysis of web pages and entering the analysis results to one or another level of the search server database.

2. Search for information based on the user's request.

3. Providing a convenient interface for searching information and viewing the search result by the user.

The working techniques used when working with one or another search tool are almost the same. Before we discuss them, let's consider the following concepts:

1. The search tool interface is presented in the form of a page with hyperlinks, a query line (search line) and query activation tools.

2. A search engine index is an information base containing the result of an analysis of web pages, compiled according to certain rules.

3. A query is a keyword or phrase that the user enters into the search bar. To form various queries, special characters ("", |, ~), and mathematical symbols (*, +, ?) are used.

Thus, if you specify a query of the same design in the search bar for each search tool, you can get different search results. It is of great importance for the user which documents will appear in the first two to three dozen documents in the search results and how well these documents correspond to the user’s expectations.

Most search tools offer two search methods - simple search(simple search) and advanced search(advanced search) with or without a special request form. Let's consider both types of search using the example of an English-language search engine.

For example, AltaVista is useful for arbitrary queries, “Something about online degrees in information technology,” while Yahoo's search tool allows you to get world news, exchange rate information, or weather forecasts.

Mostpopular technologies for searching information on the Internet.

Search engines

Web search engines are servers with huge base URL data, which automatically access WWW pages at all these addresses, examine the contents of these pages, form and enter keywords from the pages into their database (indexes the pages).

Moreover, search engine robots follow links found on pages and re-index them. Since almost any WWW page has many links to other pages, when similar work a search engine can theoretically crawl all sites on the Internet as a final result.

This type of search tools is the most famous and popular among all Internet users. Everyone has heard the names of well-known web search engines (search engines) - Yandex, Rambler, Aport.

To use this type of search tool, you need to go to it and type the keyword you are interested in in the search bar. Next, you will receive results from links stored in the search engine database that are closest to your request. To make your search more effective, pay attention to the following points in advance:

· decide on the topic of the request. What exactly do you ultimately want to find?

· pay attention to language, grammar, use of various non-literal symbols, morphology. It is also important to correctly formulate and enter keywords. Each search engine has its own form of query construction - the principle is the same, but the symbols or operators used may differ. The required request forms also vary depending on the complexity software search engines and the services they provide. One way or another, each search engine has a “Help” section, where all syntax rules, as well as recommendations and search tips, are clearly explained (screenshot of search engine pages).

· use the capabilities of different search engines. If you don't find it on Yandex, try on Google. Use advanced search services.

· To exclude documents containing certain terms, use a "-" sign before each such word. For example, if you need information about the works of Shakespeare, with the exception of "Hamlet", then enter a query in the form: "Shakespeare-Hamlet". And in order to ensure that certain links are included in the search results, use the “+” symbol. So, to find links about selling cars specifically, you need the query “sale + car”. To increase the efficiency and accuracy of your search, use combinations of these symbols.

· each link in the list of search results contains a snippet - several lines from the found document, among which your keywords appear. Before clicking on the link, evaluate the relevance of the snippet to the topic of the request. After following a link to a specific site, carefully look at the main page. As a rule, the first page is enough to understand whether you have come to the right address or not. If yes, then conduct further searches for the necessary information on the selected site (in sections of the site); if not, return to the search results and try the next link.

· remember that search engines do not produce their own information (except for explanations about themselves). A search engine is only an intermediary between the owner of the information (site) and you. Databases are constantly updated, new addresses are added to them, but the lag behind the information that actually exists in the world still remains. Simply because search engines don't work at the speed of light.

The most famous web search engines include Google, Yahoo, Alta Vista, Excite, Hot Bot, Lycos. Among the Russian-speaking ones one can highlight Yandex, Rambler, Aport.

Search engines are the largest and most valuable, but far from the only sources of information on the Internet.

Collections of links

Link collections are links sorted by topic. They differ quite greatly from each other in content, so in order to find a selection that best suits your interests, you need to go through them yourself in order to form your own opinion.

Addresses database

Address databases are special search servers that usually use classifications by type of activity, by products and services provided, and by geography. Sometimes they are supplemented with alphabetical search. Database records store information about sites that provide information about email address, organizations and postal address for a fee.

The largest English-language address database can be called: http://www.lookup.com/ - it is a category directory with many subdirectories, such as: Find Person, Phone Numbers, Name Search and others.

Once in these subdirectories, the user finds links to sites that offer information of interest to him.

Conclusion

We examined the main technologies for searching information on the Internet and presented in general terms the search tools that currently exist on the Internet, as well as the structure of search queries for the most popular Russian-language and English-language search engines and, summing up the above, we would like to note that there is no single optimal scheme There is no search for information on the Internet. Depending on the specifics of the information you need, you can use the appropriate search tools and services. And the quality of search results depends on how well search services are selected.

To summarize, we can say that there is no single optimal Internet search scheme. Depending on the specific information you need, you should use appropriate search services to find it. In principle, of course, you can always use one search engine, for example Rambler, but the more competently the search services are selected and the request for information search is compiled, the better the search results will be. And in business, the quality of information plays an important role.

Bibliography

1. Barabanov S. Intranet: step by step // Computer press. - 1997. - No. 6. - p.148-154.

2. Barabanov S. et al. Computer systems: yesterday, today, tomorrow // Computer pres. - 2007. - No. 2. - With. 152-158.

Technology for searching information on the Internet: Internet information search systems. To make a decision in each specific situation, a specialist needs to obtain the most complete and up-to-date information relevant to a given case. Search by k

Search tools

Send your good work in the knowledge base is simple. Use the form below

Plan

Introduction

Information retrieval technology

The Internet is growing at a gigantic pace and finding the information needed by a specific user is not very easy. But it is possible, since there are resources on the Internet that will help both beginners and professionals not to drown in the ocean of information.

- information portals;

- catalogs of Internet resources;

- search engines.

Search engines

Collections of links

Addresses database

Conclusion

Bibliography

1. Barabanov S. Intranet: step by step // Computer press. - 1997. - No. 6. - p.148-154.

2. Barabanov S. et al. Computer systems: yesterday, today, tomorrow // Computer pres. - 2007. - No. 2. - With. 152-158.

3. Internet - resources.

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