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37-488: The basic requirement for the inclusion of a title in the journal database is that it belongs to the genre of the continuous collective works like periodicals , serials or series issued in several parts (booklets, volumes) and which are not limited in the duration of publication (such as lexica ). The spectrum includes not only printed evidence ( print media ), but also titles from electronic journals and microforms . The database records which periodicals are available in

74-401: A periodical ) is a published work that appears in a new edition on a regular schedule. The most familiar example is a newspaper , but a magazine or a journal are also examples of periodicals. These publications cover a wide variety of topics, from academic, technical, trade, and general interest to leisure and entertainment . Articles within a periodical are usually organized around

111-441: A specific range of frequencies . The audible frequency range for humans is typically given as being between about 20 Hz and 20,000 Hz (20 kHz), though the high frequency limit usually reduces with age. Other species have different hearing ranges. For example, some dog breeds can perceive vibrations up to 60,000 Hz. In many media, such as air, the speed of sound is approximately independent of frequency, so

148-772: A '#' is used. The first issue of a periodical is sometimes also called a premiere issue or charter issue. The first issue may be preceded by dummy or zero issues. A last issue is sometimes called the final issue. Periodicals are often characterized by their period (or frequency ) of publication. This information often helps librarians make decisions about whether or not to include certain periodicals in their collection. It also helps scholars decide which journal to submit their paper to. Periodicals are often classified as either popular or scholarly. Popular periodicals are usually magazines (e.g., Ebony and Esquire ). Scholarly journals are most commonly found in libraries and databases. Examples are The Journal of Psychology and

185-411: A fractional error of Δ f f = 1 2 f T m {\textstyle {\frac {\Delta f}{f}}={\frac {1}{2fT_{\text{m}}}}} where T m {\displaystyle T_{\text{m}}} is the timing interval and f {\displaystyle f} is the measured frequency. This error decreases with frequency, so it

222-416: A known frequency near the unknown frequency is mixed with the unknown frequency in a nonlinear mixing device such as a diode . This creates a heterodyne or "beat" signal at the difference between the two frequencies. If the two signals are close together in frequency the heterodyne is low enough to be measured by a frequency counter. This process only measures the difference between the unknown frequency and

259-477: A predetermined number of editions. By contrast, a novel might be published in monthly parts, a method revived after the success of The Pickwick Papers by Charles Dickens . This approach is called part-publication , particularly when each part is from a whole work, or a serial , for example in comic books . It flourished during the nineteenth century, for example with Abraham John Valpy 's Delphin Classics , and

296-402: A repeating event is accomplished by counting the number of times that event occurs within a specific time period, then dividing the count by the period. For example, if 71 events occur within 15 seconds the frequency is: f = 71 15 s ≈ 4.73 Hz . {\displaystyle f={\frac {71}{15\,{\text{s}}}}\approx 4.73\,{\text{Hz}}.} If

333-479: A second (60 seconds divided by 120). For cyclical phenomena such as oscillations , waves , or for examples of simple harmonic motion , the term frequency is defined as the number of cycles or repetitions per unit of time. The conventional symbol for frequency is f or ν (the Greek letter nu ) is also used. The period T is the time taken to complete one cycle of an oscillation or rotation. The frequency and

370-401: A serial publication. A book series is also a serial publication, but is not typically called a periodical. An encyclopedia or dictionary is also a book, and might be called a serial publication if it is published in many different editions over time. Periodicals are typically published and referenced by volume and issue (also known as issue number or number). Volume typically refers to

407-400: A single main subject or theme and include a title, date of publication, author(s), and brief summary of the article. A periodical typically contains an editorial section that comments on subjects of interest to its readers. Other common features are reviews of recently published books and films, columns that express the authors' opinions about various topics, and advertisements. A periodical is

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444-495: Is called a radio wave . Likewise, an electromagnetic wave with a frequency higher than 8 × 10  Hz will also be invisible to the human eye; such waves are called ultraviolet (UV) radiation. Even higher-frequency waves are called X-rays , and higher still are gamma rays . All of these waves, from the lowest-frequency radio waves to the highest-frequency gamma rays, are fundamentally the same, and they are all called electromagnetic radiation . They all travel through vacuum at

481-405: Is equivalent to one hertz. As a matter of convenience, longer and slower waves, such as ocean surface waves , are more typically described by wave period rather than frequency. Short and fast waves, like audio and radio, are usually described by their frequency. Some commonly used conversions are listed below: For periodic waves in nondispersive media (that is, media in which the wave speed

518-411: Is generally a problem at low frequencies where the number of counts N is small. An old method of measuring the frequency of rotating or vibrating objects is to use a stroboscope . This is an intense repetitively flashing light ( strobe light ) whose frequency can be adjusted with a calibrated timing circuit. The strobe light is pointed at the rotating object and the frequency adjusted up and down. When

555-458: Is independent of frequency), frequency has an inverse relationship to the wavelength , λ ( lambda ). Even in dispersive media, the frequency f of a sinusoidal wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave: f = v λ . {\displaystyle f={\frac {v}{\lambda }}.} In the special case of electromagnetic waves in vacuum , then v = c , where c

592-402: Is red light, 800 THz ( 8 × 10  Hz ) is violet light, and between these (in the range 400–800 THz) are all the other colors of the visible spectrum . An electromagnetic wave with a frequency less than 4 × 10  Hz will be invisible to the human eye; such waves are called infrared (IR) radiation. At even lower frequency, the wave is called a microwave , and at still lower frequencies it

629-400: Is the speed of light in vacuum, and this expression becomes f = c λ . {\displaystyle f={\frac {c}{\lambda }}.} When monochromatic waves travel from one medium to another, their frequency remains the same—only their wavelength and speed change. Measurement of frequency can be done in the following ways: Calculating the frequency of

666-400: Is the number of occurrences of a repeating event per unit of time . It is also occasionally referred to as temporal frequency for clarity and to distinguish it from spatial frequency . Ordinary frequency is related to angular frequency (symbol ω , with SI unit radian per second) by a factor of 2 π . The period (symbol T ) is the interval of time between events, so the period is

703-558: The Journal of Social Work . Trade magazines are also examples of periodicals. They are written for an audience of professionals in the world. As of the early 1990s, there were over 6,000 academic, business, scientific, technical, and trade publications in the United States alone. These examples are related to the idea of an indefinitely continuing cycle of production and publication: magazines plan to continue publishing, not to stop after

740-626: The metadata has been under the Creative Commons Zero (CC0 1.0) license and is therefore released for reuse. In the 1970s, the former Gemeinsame Körperschaftsdatei (GKD) was created from the catalogue data of the ZDB. This was incorporated into the Gemeinsame Normdatei (GND) in April 2012. Periodical A periodical literature (also called a periodical publication or simply

777-408: The reciprocal of the frequency: T = 1/ f . Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves , and light . For example, if a heart beats at a frequency of 120 times per minute (2 hertz), the period—the time interval between beats—is half

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814-486: The alternating current in household electrical outlets is 60 Hz (between the tones B ♭ and B; that is, a minor third above the European frequency). The frequency of the ' hum ' in an audio recording can show in which of these general regions the recording was made. Aperiodic frequency is the rate of incidence or occurrence of non- cyclic phenomena, including random processes such as radioactive decay . It

851-421: The frequency of the strobe equals the frequency of the rotating or vibrating object, the object completes one cycle of oscillation and returns to its original position between the flashes of light, so when illuminated by the strobe the object appears stationary. Then the frequency can be read from the calibrated readout on the stroboscope. A downside of this method is that an object rotating at an integer multiple of

888-408: The holdings of German libraries, it also lists those from Austria and (to a limited extent) other European countries. As one of the world's largest database of its kind, the ZDB comprises more than 1.9 million titles in all languages from 1500 up to the present day and it contains over 17 million ownership records of around 3630 German and Austrian libraries for these titles. Since June 2014, most of

925-470: The individual participating libraries and allows searching for magazine titles. The so-called inventory data record provides information about which volumes are available in which library. In contrast, the ZDB does not list any article title . Due to its range of title and inventory records, the ZDB is the backbone of interlibrary loan system in Germany for the aforementioned types of literature. In addition to

962-417: The latest edition of this style, a work with volume number 17 and issue number 3 may be written as follows: Sometimes, periodicals are numbered in absolute numbers instead of volume-relative numbers, typically since the start of the publication. In rare cases, periodicals even provide both: a relative issue number and an absolute number. There is no universal standard for indicating absolute numbers, but often

999-545: The number of counts is not very large, it is more accurate to measure the time interval for a predetermined number of occurrences, rather than the number of occurrences within a specified time. The latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an average error in the calculated frequency of Δ f = 1 2 T m {\textstyle \Delta f={\frac {1}{2T_{\text{m}}}}} , or

1036-461: The number of years the publication has been circulated, and issue refers to how many times that periodical has been published during that year. For example, the April 2011 publication of a monthly magazine first published in 2002 would be listed as, "volume 10, issue 4". Roman numerals are sometimes used in reference to the volume number. When citing a work in a periodical, there are standardized formats such as The Chicago Manual of Style . In

1073-581: The period are related by the equation f = 1 T . {\displaystyle f={\frac {1}{T}}.} The term temporal frequency is used to emphasise that the frequency is characterised by the number of occurrences of a repeating event per unit time. The SI unit of frequency is the hertz (Hz), named after the German physicist Heinrich Hertz by the International Electrotechnical Commission in 1930. It

1110-410: The reference frequency. To convert higher frequencies, several stages of heterodyning can be used. Current research is extending this method to infrared and light frequencies ( optical heterodyne detection ). Visible light is an electromagnetic wave , consisting of oscillating electric and magnetic fields traveling through space. The frequency of the wave determines its color: 400 THz ( 4 × 10 Hz)

1147-560: The rotation rate of a shaft, mechanical vibrations, or sound waves , can be converted to a repetitive electronic signal by transducers and the signal applied to a frequency counter. As of 2018, frequency counters can cover the range up to about 100 GHz. This represents the limit of direct counting methods; frequencies above this must be measured by indirect methods. Above the range of frequency counters, frequencies of electromagnetic signals are often measured indirectly utilizing heterodyning ( frequency conversion ). A reference signal of

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1184-414: The same speed (the speed of light), giving them wavelengths inversely proportional to their frequencies. c = f λ , {\displaystyle \displaystyle c=f\lambda ,} where c is the speed of light ( c in vacuum or less in other media), f is the frequency and λ is the wavelength. In dispersive media , such as glass, the speed depends somewhat on frequency, so

1221-461: The strobing frequency will also appear stationary. Higher frequencies are usually measured with a frequency counter . This is an electronic instrument which measures the frequency of an applied repetitive electronic signal and displays the result in hertz on a digital display . It uses digital logic to count the number of cycles during a time interval established by a precision quartz time base. Cyclic processes that are not electrical, such as

1258-419: The wavelength is not quite inversely proportional to frequency. Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances. In general, frequency components of a sound determine its "color", its timbre . When speaking about the frequency (in singular) of a sound, it means the property that most determines its pitch . The frequencies an ear can hear are limited to

1295-455: The wavelength of the sound waves (distance between repetitions) is approximately inversely proportional to frequency. In Europe , Africa , Australia , southern South America , most of Asia , and Russia , the frequency of the alternating current in household electrical outlets is 50 Hz (close to the tone G), whereas in North America and northern South America, the frequency of

1332-453: Was adopted by the CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, cycle per second (cps). The SI unit for the period, as for all measurements of time, is the second . A traditional unit of frequency used with rotating mechanical devices, where it is termed rotational frequency , is revolution per minute , abbreviated r/min or rpm. 60 rpm

1369-587: Was not restricted to fiction . The International Standard Serial Number (ISSN) is to serial publications (and by extension, periodicals) what the International Standard Book Number (ISBN) is to books: a standardized reference number. Postal services often carry periodicals at a preferential rate; for example, Second Class Mail in the United States only applies to publications issued at least quarterly. Frequency Frequency (symbol f ), most often measured in hertz (symbol: Hz),

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