In this chapter, time-dependent failures will be dealt with. 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. The reason behind this is the gradual growth of the companies which are in need of the place to store their data. Usability. 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. Some objects could be repaired after failure but are not, because of economic reasons. One can thus speak of a flow of operations and repairs (Fig. Cloud Computingis gaining more and more popularity day by day. Submitted: January 8th 2016Reviewed: February 3rd 2016Published: April 13th 2016, Home > Books > Concise Reliability for Engineers. 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). In complex systems, the failed part can also be replaced by a good one to reduce the downtime. 3a in Chapter 2. After a failure, the object is repaired and continues working. it performs tasks without manual intervention. Knowledge of what characteristics a record has is one way to make it possible to formalize records. The main characteristics of a computer are : The computer can process data very fast, at the rate of millions of instructions per second. ADVERTISEMENTS: This article throws light upon the four important characteristics of a good test. 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.]. Examples for better understanding are included. Computers can perform several tasks at a time. If we want to know when the failures can occur, their time characteristics are also important. How? For example, the computer can accurately give the result of division of any two numbers up to 10 decimal places. 1. Reliability is usually characterized by the probability of failure or by the time to failure. 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. To reliably ensure the public traffic, 36 buses are thus necessary. 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. 2). So in measurement reliability is the consistency with which a test yields the same result […] Two experienced radiologists measured the properties of 21 images of spiculated masses. If a repairable item fails, it is repaired and again put into operation. The first generation computers were used vaccum tubes as the main electronic part. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Data : Data is a raw material of information. In theory, a reliable product is totally free of technical errors. The mean time to failure can be calculated using Equation (5). Reliability is an attribute of any computer-related component (software, or hardware, or a network, for example) that consistently performs according to its specifications. Characteristics of Reliability, Concise Reliability for Engineers, Jaroslav Mencik, IntechOpen, DOI: 10.5772/62356. Reliability characteristics for a technical installation are very important for the design of the installation. The mean time to failure can be calculated from operational records as the average of the group of measured times to failure. The failed item is discarded. Secondary storage devices like floppy disk and compact disk can store a large amount of data permanently. A very important reliability characteristic is failure rate λ(t). The number of reserve vehicles is 36 – 30 = 6 buses. How many reserve buses (Nr) are necessary? The coefficient of availability simply says what part of the total time is available for useful work. Information : Proper collection of the data is called information.Characteristics of Computer 1. © 2016 The Author(s). An aid for easier remembering: the letter F is also the first letter of the word failure. 1b) and is called reliability function (therefore the symbol R). If failure is considered as a single event (e.g. Contact our London head office or media team here. Coefficient of unavailability: COU = ∑tdown,j/ttot = 11/(104 + 11) = 0.09565. The four characteristics are: 1. It has been found that cloud computing is a model for enabling ubiquitous, convenient, on-demand network access the computing re… This is typical of simple unrepairable objects, such as lamp bulbs, screws, windows, integrated circuits, and many inexpensive parts. Help us write another book on this subject and reach those readers. Unlike probability, which is nondimensional, failure rate has a dimension. The basic quantity for unrepaired objects is the time to failure tf. 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. 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 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. In a town, N = 30 buses are necessary for assuring reliable traffic on 15 routes. In addition to the net time of the repair, some logistic times are often necessary, which sometimes last much longer than the repair. 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. Two computers can be connected to send & receive data. 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. 1 month or year), ∑tdown is the sum of down times in this interval, and ttot is the total investigated time. What is the total necessary number of buses Ntot? 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. 1. 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. 1. With the above numbers, Ntot = 30/0.85 = 35.29. The computer has become a huge contributor in business. Also, the cost of developing and maintaining the software should be low. Licensee IntechOpen. 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. When used for a longer period of time, the computer does not get tired or fatigued. After the next failure, it is again repaired and put into operation, etc. Large volumes of data and information can be stored in the computer and also retrieved whenever required. Mean time to repair and between repairs, coefficient of availability and unavailability, failure rate. The Basic Characteristics of Computer are as following :: Speed; Accuracy; Memory; Diligence; Versatility; Reliability; Low Cost & Reduced Size; Automatic; No Feeling & No IQ; Speed :: Accuracy Computer provides a high degree of accuracy. Main characteristics of a computer are Speed, Accuracy , Diligence, Storage Capability, Versatility , They can communicate, We can do multitasking Computers have the ability to communicate, but of course there needs some sort of connection (either Wired or Wireless connection). • 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. Equation (1) relates mutually three variables: λ, f, and R. Fortunately, it can be transformed into simple relationships of two quantities. 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. To date our community has made over 100 million downloads. It can perform different types of tasks with the same ease. (a) Failure function F(t) and (b) reliability function R(t). 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. By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers. 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). However, due to failures and maintenance, several buses are unavailable every day. Computer is an electronic device which is used to store the data, as per given instructions it gives results quickly and accurately. In such cases, modified formulas for MTTF must be used; see Chapter 20 or [1]. Good information is relevant for its purpose, sufficiently accurate for its purpose, complete enough for the problem, reliable and targeted to the right person. Available from: Department of Mechanics, Materials and Machine Parts, Jan Perner Transport Faculty, University of Pardubice, Czech Republic. The complementary quantity, coefficient of unavailability. 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. It has a strong focus on process management, system security, and uptime. The Institute of Electrical and Electronics Engineers ( IEEE ) sponsors an organization devoted to reliability in engineering known as the IEEE Reliability Society (IEEE RS). Validity 3. Built by scientists, for scientists. 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. 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. 1a). Reliability : The output generated by the computer is very reliable as long as the data is reliable. Users usually experience less issues in Linux. Software is defined as collection of computer programs, procedures, rules and data. 1. A limited amount of data can be stored, temporarily, in the primary memory. A computer is free from monetary and tiredness. 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. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. The goal of this study was to assess the reliability of measurements of the physical characteristics of spiculated masses on mammography. 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. As it follows from long-term records, the mean availability of the buses is COA = 0.85. Outside of specific contexts, computer performance is estimated in terms of accuracy, efficiency and speed of executing computer program instructions. says how many percent of the total time are downtimes. In this case, the term hazard rate is used as more appropriate, but the expression failure rate is also very common. We have defined new structural test coverage criteria for FBD programs in which dataflow-centric characteristics of FBD programs were well reflected. • Lack of reliability means losing a packet or acknowledgement which then requires retransmission. a machine) does not work. The increasing popularity of computer has proved that it is very powerful and useful machine. The basic reliability characteristics are explained: time to failure, probability of failure and of failure-free operation, repairable and unrepairable objects. For memory devices punch card and paper tapes were used. Failure rate (1) thus corresponds to the failure probability density, λ(t) = f(t). 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. Specific attention is paid to reliability and complexity assessment of computer based task and the correlation between these vital characteristics of human performance. Reliability: Because, computer is an electronic device thus it perform all operations with 100 % accuracy and reliability. Reliability. 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. 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. collapse of a bridge), regardless of the time, only its probability is of interest. Versatility: versatility is one of the most wonderful things about the computer. Friends & family can connect over the internet and share files, photos & videos online. In practice, vendors commonly express product reliability as a percentage. Experience and research shows that good information has numerous qualities. A) Computer Characteristics & … 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. [Remark: Formula (13) is only approximate and often exhibits big scatter. Reliability is a very big characteristics of computer. The characteristics of computer that are speed, accuracy, diligence, versatility,Power of Remembering,No IQ,No Feeling and storage capacity. Important flow characteristics of the QoS are given below: 1. The reliability, availability, and serviceability(or "RAS") of a computer system have always been important factors in data processing. One moment it can do any one operation and next moment if can perform any other operation. Magnetic drums are also used for storage .At that time memory was very expensive. First, it can be rewritten as follows: The separation of the variables leads to the differential equation of first order. 4. 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. 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