Reliability is an attribute of any computer-related component (software, or hardware, or a network, for example) that consistently performs according to its specifications. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. • However, the sensitivity of application programs to reliability is not the same. Reliability. The basic quantity for unrepaired objects is the time to failure tf. This ratio approximately expresses the probability of failure F(t) during the time interval <0; t>; Function F(t) is the distribution function of the time to failure, also called failure function (Fig. A more accurate value of the instantaneous failure rate λ(t) can be obtained from several nf values occurring in a wider interval around the time t.]. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. It has long been considered one of three related attributes that must be considered when making, buying, or using a computer product or component. The four characteristics are: 1. For example, COA = 0.9 means that, on average, the vehicle (or machine) is only 90% of all time in operation, and 10% of the total time it is idle due to failures. If we want to know when the failures can occur, their time characteristics are also important. Unlike probability, which is nondimensional, failure rate has a dimension. Coefficient of unavailability: COU = ∑tdown,j/ttot = 11/(104 + 11) = 0.09565. An aid for easier remembering: the letter F is also the first letter of the word failure. Magnetic drums are also used for storage .At that time memory was very expensive. We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Jaroslav Menčík (April 13th 2016). The three basic metrics of RAM are (not surprisingly) Reliability, Maintainability, and Availability. The fraction of failed objects, F(t), increases with time, and the fraction of objects that have not failed, R(t), decreases. It has been found that cloud computing is a model for enabling ubiquitous, convenient, on-demand network access the computing re… In practice, vendors commonly express product reliability as a percentage. The term reliability refers to the ability of a computer-related hardware or software component to consistently perform according to its specifications. 1. The coefficient of availability simply says what part of the total time is available for useful work. First and foremost, a software product must meet all the requirements of the customer or end-user. After the next failure, it is again repaired and put into operation, etc. Users usually experience less issues in Linux. Objectivity 4. Well before going into technical characteristics, I would like to state the obvious expectations one has from any software. 1b) and is called reliability function (therefore the symbol R). A limited amount of data can be stored, temporarily, in the primary memory. Failure rate (1) thus corresponds to the failure probability density, λ(t) = f(t). Useful information on reliability is obtained from a very simple characteristic, the average or mean time to failure or MTTF, which is generally defined as. Characteristics of computer: Accuracy Accuracy of a computer is consistently high and the degree of accuracy of a particular computer depends on the instructions and the type of processor. We share our knowledge and peer-reveiwed research papers with libraries, scientific and engineering societies, and also work with corporate R&D departments and government entities. The complementary quantity, coefficient of unavailability. How many reserve buses (Nr) are necessary? Specific attention is paid to reliability and complexity assessment of computer based task and the correlation between these vital characteristics of human performance. Information : Proper collection of the data is called information.Characteristics of Computer 1. Submitted: January 8th 2016Reviewed: February 3rd 2016Published: April 13th 2016, Home > Books > Concise Reliability for Engineers. Friends & family can connect over the internet and share files, photos & videos online. In computing, computer performance is the amount of useful work accomplished by a computer system. Although Microsoft Windows has made great improvements in reliability in recent years, it's considered less reliable than Linux. The increasing popularity of computer has proved that it is very powerful and useful machine. For example, the computer can accurately give the result of division of any two numbers up to 10 decimal places. Reliability is a synonym for assurance, which is the term used by the ITU and ATM Forum. A) Computer Characteristics & … Reliability : The output generated by the computer is very reliable as long as the data is reliable. The reliability, availability, and serviceability(or "RAS") of a computer system have always been important factors in data processing. The reason behind this is the gradual growth of the companies which are in need of the place to store their data. Mean time between failures MTBF = ∑tup,j/n = (28 + 16 + 20 + 10 + 30)/5 = 104/5 = 20.8 h. Mean time to repair MTTR = ∑tdown,j/n = (3 + 2 + 1 + 3 + 2)/5 = 11/5 = 2.2 h. Coefficient of availability COA = ∑tup,j/ttot = ∑tup,j/(∑tup,j + ∑tdown,j) = 104/(104 + 11) = 0.90435. When it comes to high computer performance, one or more of the following factors might be involved: Characteristic # 1. MTBF is the mean time (of operation) between failures and MTTR is the mean time to repair (generally, the mean down time caused by failures). Built by scientists, for scientists. R is complementary to F. The probability density of the time to failure, f(t), expresses the probability of failure during a very short time interval ∆t at time t, related to this interval: the unit is s-1 or h-1. Knowledge of what characteristics a record has is one way to make it possible to formalize records. The probability that the machine will be able to work at any instant equals the coefficient of availability; R = COA = 0.90435 ≈ 90,4%. Login to your personal dashboard for more detailed statistics on your publications. 3a in Chapter 2. It also expresses the average probability that the object will be able to fulfill the expected task at any instant. Similarly, F = COU = 0.09565 ≈ 9.6%. Help us write another book on this subject and reach those readers. In other words, there is a 90% probability that the object will be available when needed and a 10% probability that it will not be available. This often is not an issue for unicast protocols, but it may become a problem for reliable multicast protocols. The coefficient of availability can be calculated as the number of operable buses, Nup, divided by the total number of vehicles, COA = Nup/Ntot, from which Ntot = Nup/COA. For example you can listen to songs, download movies, and prepare word documents all at the same time. Also, a living being cannot be repaired, if it has died. Multitasking is also a computer characteristic. The probability of failure-free operation R(t) expresses the probability that no failure occurs before the time t; R(t) shows the gradual loss of serviceable objects (Fig. Mean time to repair and between repairs, coefficient of availability and unavailability, failure rate. a machine) does not work. Cloud Computingis gaining more and more popularity day by day. Large volumes of data and information can be stored in the computer and also retrieved whenever required. Available from: Department of Mechanics, Materials and Machine Parts, Jan Perner Transport Faculty, University of Pardubice, Czech Republic. A list of popular first generation computers ENIAC, UNIVAC,EDVAC, and EDSAC. Another way of calculation: COA = MTBF/(MTBF + MTTR) = 20.8/(20.8 + 2.2) = 0.90435 and COU = MTTR/(MTBF + MTTR) = 2.2/(20.8 + 2.2) = 0.09565. f(t) is the probability density of failure (=dF/dt), and R(t) is the probability that the object was operated until the time t. An illustrative idea of failure rate can be gained from a simple formula for its calculation from the data from operation: n is the total number of the monitored objects, nf(t) is the number of the objects failed until the time t, [nf(t + ∆t) – nf(t)] is the number of objects failed during the time from t to t + ∆t, and ∆t is a short time interval. Versatility: versatility is one of the most wonderful things about the computer. In such cases, modified formulas for MTTF must be used; see Chapter 20 or [1]. At one moment you can use the computer to prepare a letter document and in the next moment you may play music or print a document. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too. Reliable protocols typically incur more overhead than unreliable protocols, and as a result, function more slowly and with less scalability. Failure rate expresses the probability of failure during a time unit but is related only to those objects that have remained in operation until the time t, that is, those that have not failed before the time t. Failure rate is defined as. Two experienced radiologists measured the properties of 21 images of spiculated masses. The Windows 10 reliability monitor display is made up of three distinct areas--each area provides specific information on a timeline describing events … 4. The characteristics of computer that are speed, accuracy, diligence, versatility,Power of Remembering,No IQ,No Feeling and storage capacity. Reliability is usually characterized by the probability of failure or by the time to failure. One moment it can do any one operation and next moment if can perform any other operation. Computers have the ability to communicate, but of course there needs some sort of connection (either Wired or Wireless connection). A computer is free from monetary and tiredness. It also expresses the probability that the object will not be able to perform its function at a demanded instant. Data : Data is a raw material of information. Two computers can be connected to send & receive data. Validity 3. However, due to failures and maintenance, several buses are unavailable every day. The mean time to failure can be calculated using Equation (5). Flow of operations (uptimes, tup) and repairs (downtimes, td). It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. Reliability 2. Outside of specific contexts, computer performance is estimated in terms of accuracy, efficiency and speed of executing computer program instructions. Special software’s are used for text and video chat. To date our community has made over 100 million downloads. In complex systems, the failed part can also be replaced by a good one to reduce the downtime. The failed item is discarded. The right-hand side of Equation (4) indicates how the probability density can be determined from empirical data, nf(t + ∆t) expresses the number of failed parts from 0 to t + ∆t, and nf(t) is the number of failures that occurred until the time t. In fact, probability density f(t) shows the distribution of failures in time, similar to Fig. says how many percent of the total time are downtimes. Basically, failure rate expresses the probability of failure during a time unit. Open Access is an initiative that aims to make scientific research freely available to all. • Survey participants' overall satisfaction ("extremely satisfied" or "very satisfied") with laptop reliability from all companies has improved from 67.6 percent in 2008 to 81.9 percent in 2011. it performs tasks without manual intervention. Thus, the term nonrepaired objects can be used as more universal. 1a). The number of reserve vehicles is 36 – 30 = 6 buses. The coefficient of availability can also be calculated as. For memory devices punch card and paper tapes were used. Main characteristics of a computer are Speed, Accuracy , Diligence, Storage Capability, Versatility , They can communicate, We can do multitasking Software Characteristics are classified into six major components: These components are described below: Functionality: It refers to the degree of performance of the software against its intended purpose. A computer is reliable as it gives consistent result for similar set of data i.e., if we give same set of input any number of times, we will get the same result. The coefficient of availability, COA, is defined as [2, 3]: where ∑tup is the sum of times of operation during the investigated interval (e.g. SPEED : In general, no human being can compete to solving the complex computation, faster than computer. They uses two types of computer programming languages, machine language and assembly language. It must reminded here that the time of a repair is not always the same as the downtime when the object (e.g. In a town, N = 30 buses are necessary for assuring reliable traffic on 15 routes. The integration and transformation lead to the following expression for the probability of operation as a function of time: With respect to Equations (12) to (17), any of the four quantities f, F, R, and λ is sufficient for the determination of any of the remaining three quantities. In theory, a reliable product is totally free of technical errors. • Lack of reliability means losing a packet or acknowledgement which then requires retransmission. Reliability: The dictionary meaning of reliability is consistency, dependence or trust. Two cases must be distinguished, depending on whether the object after failure is repaired or not. Remark: Equation (6) is appropriate if all objects have failed. Some objects could be repaired after failure but are not, because of economic reasons. The computer has become a huge contributor in business. First, it can be rewritten as follows: The separation of the variables leads to the differential equation of first order. HeadquartersIntechOpen Limited5 Princes Gate Court,London, SW7 2QJ,UNITED KINGDOM. It can perform different types of tasks with the same ease. QoS is an overall performance measure of the computer network. The Basic Characteristics of Computer are as following :: Speed; Accuracy; Memory; Diligence; Versatility; Reliability; Low Cost & Reduced Size; Automatic; No Feeling & No IQ; Speed :: • Reliability is an important characteristic of flow. With the above numbers, Ntot = 30/0.85 = 35.29. Express the average probability (in %) that the machine (a) will be able to work at any instant (R) and (b) will not be able to work (F). The first generation computers were used vaccum tubes as the main electronic part. Licensee IntechOpen. Therefore, companies are in competition to provide large space to store data along with the various features and quality service. To reliably ensure the public traffic, 36 buses are thus necessary. Reliability characteristics for a technical installation are very important for the design of the installation. By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers. In this chapter, time-dependent failures will be dealt with. collapse of a bridge), regardless of the time, only its probability is of interest. But for a particular computer, each and every calculation is performed. Important flow characteristics of the QoS are given below: 1. The power and usefulness of this popular machine is mainly due to the following features:-a) Speed b) Accuracy c) Diligence d) Versatile e) Storage f) Automatic g) Reliability a) Speed: - Computer can work at a very high speed. 1. This is typical of simple unrepairable objects, such as lamp bulbs, screws, windows, integrated circuits, and many inexpensive parts. The basic reliability characteristics are explained: time to failure, probability of failure and of failure-free operation, repairable and unrepairable objects. Computers can perform several tasks at a time. However, in most cases, the exponential distribution is used, and a single value, the mean time to failure (MTTF) for non-restorable systems, or mean time between failures (MTBF for restorable systems are used). Characteristics of Reliability, Concise Reliability for Engineers, Jaroslav Mencik, IntechOpen, DOI: 10.5772/62356. How? The images used in this study were obtained from the Digital Database for Screening Mammography. The Business Value of the Internet The internet is a global network of interlinked computers operating on a standard protocol that allows information exchange. The computer program presented in this paper applies to this type of graph and evaluates upper and lower bounds to three system-reliability characteristics: availability, mean time-to-fail, and mean time-to-repair. Examples for better understanding are included. The basic reliability characteristics are explained: time to failure, probability of failure and of failure-free operation, repairable and unrepairable objects. Secondary storage devices like floppy disk and compact disk can store a large amount of data permanently. If a group of identical objects is put into operation, the individual pieces begin to fail after some time, and it is also possible to express the number of failed pieces as a function of time, nf(t). Software is defined as collection of computer programs, procedures, rules and data. These systems follow the same basic principles by which manual systems operate. ACCURACY : Since Computer is programmed, so what ever input we give it gives result with accuratly. For example, calculation and generation of salary slips of thousands of employees of an organization, weather forecasting that requires analysis of a large amount of data related to temperature, pressure and humidity of various places, etc. 2). We are IntechOpen, the world's leading publisher of Open Access books. People use computer in business because of its features of storing volumes of data, multitasking ,performing complex calculation, working more efficiently than humans, it doesn’t have human traits such as envy,jealousy,tiredness, etc. Good information is relevant for its purpose, sufficiently accurate for its purpose, complete enough for the problem, reliable and targeted to the right person. If the reliability characteristics are taken into account as early as at the development stage and purposefully manipulated, huge costs can be saved on the basis of the greater availability which results. Automation Computer performs all the tasks automatically i.e. Our team is growing all the time, so we’re always on the lookout for smart people who want to help us reshape the world of scientific publishing. Computerized accounting systems include the use of computers and a software application or program to aid companies in recording, reporting and analyzing financial information. The mean time between failures and mean time to repair can be used to characterize the probability that the object will be serviceable at a certain instant or not. Experience and research shows that good information has numerous qualities. The monitoring of operation and repairs of a certain machine has given the following durations of operations and repairs: tup,1 = 28 h, tdown,1 = 3 h, tup,2 = 16 h, tdown,2 = 2 h, tup,3 = 20 h, tdown,3 = 1 h, tup,4 = 10 h, tdown,4 = 3 h, tup,5 = 30 h, and tdown,5 = 2 h. Determine the mean time between failures and mean time to repair. (a) Failure function F(t) and (b) reliability function R(t). Contact our London head office or media team here. Reliability: Linux is notoriously reliable and secure. Computer is an electronic device which is used to store the data, as per given instructions it gives results quickly and accurately. Basic characteristics about computer are: … One can thus speak of a flow of operations and repairs (Fig. Electronic time per calculation ranged from 0.1 milliseconds to1 milliseconds. Determine the coefficient of availability (COA) and unavailability (COU). It can perform long and complex calculations with the same speed and accuracy from the start till the end. ADVERTISEMENTS: This article throws light upon the four important characteristics of a good test. As it follows from long-term records, the mean availability of the buses is COA = 0.85. If components with very long life are tested, the tests are usually terminated after some predefined time or after failure of certain fraction of all components. Here, one must distinguish between unrepaired and repaired objects depending on whether the failed object is discarded or repaired and again put into service. The mean time to failure can be calculated from operational records as the average of the group of measured times to failure. Mean time to repair and between repairs, coefficient of availability and unavailability, failure rate. After a failure, the object is repaired and continues working. The number of working objects remains constant, so that R(t) = 1. It is t-1, for example, h-1 or % per hour for machines, components, or appliances, km-1 for vehicles, etc. The main characteristics of a computer are : The computer can process data very fast, at the rate of millions of instructions per second. Complete List and Explanation on Computer Characteristics. Reliability: Because, computer is an electronic device thus it perform all operations with 100 % accuracy and reliability. Good information is that which is used and which creates value. [Remark: Formula (13) is only approximate and often exhibits big scatter. Some calculations that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. When we say that a particular computer system "exhibits RAS characteristics,"we mean that its design places a high priority on the system remaining in service Computer is versatile in nature. The Institute of Electrical and Electronics Engineers ( IEEE ) sponsors an organization devoted to reliability in engineering known as the IEEE Reliability Society (IEEE RS). When used for a longer period of time, the computer does not get tired or fatigued. If a repairable item fails, it is repaired and again put into operation. Accuracy Computer provides a high degree of accuracy. Characteristics of Information. 1. 1 month or year), ∑tdown is the sum of down times in this interval, and ttot is the total investigated time. Equation (1) relates mutually three variables: λ, f, and R. Fortunately, it can be transformed into simple relationships of two quantities. Reliability is a very big characteristics of computer. Today almost all the big industries or big e-Commerce companies like Amazon and Flipkart, and big search engine companies like - Google and Bing, all these companies are dependent on computers. Usability. © 2016 The Author(s). If we denote each interval as “uptime” tup or “downtime” tdown, we can calculate the mean time between failures, MTBF, and the mean time to repair, MTTR: If data for a high number of values tup and tdown are available, the distribution of these times can also be obtained and used. The qualitative and quantitative description of computer based task performance is utilized as an example. Reliability can be characterized in terms of the parameters, mean, or any percentile of a reliability distribution. If failure is considered as a single event (e.g. It has a strong focus on process management, system security, and uptime. So in measurement reliability is the consistency with which a test yields the same result […] Even the simple records from operation can give the basic values of probabilities and reliability. We have defined new structural test coverage criteria for FBD programs in which dataflow-centric characteristics of FBD programs were well reflected. Also, the cost of developing and maintaining the software should be low. The goal of this study was to assess the reliability of measurements of the physical characteristics of spiculated masses on mammography. Reliability If a packet gets lost or acknowledgement is not received (at sender), the re-transmission of data will be needed. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. A very important reliability characteristic is failure rate λ(t). In addition to the net time of the repair, some logistic times are often necessary, which sometimes last much longer than the repair. A more universal quantity is the relative proportion of the failed items, that is, the number of the failed items related to the number n of monitored objects, nf(t)/n. Reliability can affect only error prone by human mind. In this case, the term hazard rate is used as more appropriate, but the expression failure rate is also very common. *Address all correspondence to: jaroslav.mencik@upce.cz. Brief introduction to this section that descibes Open Access especially from an IntechOpen perspective, Want to get in touch? What is the total necessary number of buses Ntot? 1. , temporarily, in the primary memory efficiency and speed of executing computer program instructions or trust headquartersintechopen Princes! Also retrieved whenever required, failure rate is also the first generation ENIAC... It 's considered less reliable than Linux & receive data can affect only error prone human! Has become a problem for reliable multicast protocols after a failure, it is very and! That which is used as more appropriate, but it may become a huge contributor business! Repaired, if it has a dimension traffic, 36 buses are unavailable every day,,... Correspondence to: jaroslav.mencik @ upce.cz, as well as business professionals basic values probabilities... Leading publisher of Open Access especially from an IntechOpen perspective, Want to in... There needs some sort of connection ( either Wired or Wireless connection ) measurements., no human being can compete to solving the complex computation, faster computer! 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