Multiple-Stage Policies for a Server System with Illegal Access

Author(s):  
Mitsuhiro Imaizumi ◽  
Mitsutaka Kimura

As the Internet technology has developed, the demands for the improvement of the reliability and security of the system connected with the Internet have increased. Although various services are performed on the Internet, illegal access on the Internet has become a problem in recent years. This paper formulates stochastic models for a system with illegal access. The server has the function of IDS, and illegal access is checked in multiple stages which consist of simple check, detailed check and dynamic check. We apply the theory of Markov renewal processes to a system with illegal access, and derive the mean time and the expected checking number until a server system becomes faulty. Further, optimal policies which minimize the expected cost are discussed. Finally, numerical examples are given.

Author(s):  
Mitsuhiro Imaizumi ◽  
Mitsutaka Kimura

This paper formulates a stochastic model for a system with illegal access. The server has the function of IDS, and illegal access is checked in multiple stages which consist of simple check and detailed check. In this model, we consider type I and II errors of simple check and a type I error of detailed check. There are two cases where IDS judges the occurrence of illegal access erroneously. One is when illegal access does not occur, and the other is when illegal access occurs. We apply the theory of Markov renewal processes to a system with illegal access, and derive the mean time and the expected checking number until a server system becomes faulty. Further, an optimal policy which minimizes the expected cost is discussed. Finally, numerical examples are given.


Author(s):  
Mitsuhiro Imaizumi ◽  
Mitsutaka Kimura

Cyber attack on the Internet has become a problem in recent years, and it has been becoming more sophisticated and complicated. As one of schemes to detect cyber attack, IDS has been widely used. IDS can detect cyber attack based on the signature which is the pattern of cyber attack and so on. There are signature-based and anomaly-based detection methods in terms of IDS. Signature detection compares activity and behavior to signatures of known attacks. Signatures need to be updated regularly to detect a new type of attacks. This paper considers extended stochastic models for a server system with signature update. The server has the function of IDS. In this model, we consider type II error where IDS judges the occurrence of cyber attack erroneously when it occurs. We assume that the check with signature update is performed at [Formula: see text]th check or every [Formula: see text] checks. We obtain the expected costs until cyber attack is detected and discuss the optimal policies which minimize them. Finally, numerical examples are given.


1998 ◽  
Vol 2 (2) ◽  
pp. 133-145 ◽  
Author(s):  
Dylan Shi

Consider a series system consisting of n components of k types. Whenever a unit fails, it is replaced immediately by a new one to keep the system working. Under the assumption that all the life lengths of the components are independent and exponentially distributed and that the replacement policies depend only on the present state of the system at each failure, the system may be represented by a birth and death process. The existence of the optimum replacement policies are discussed and the ε-optimal policies axe derived. If the past experience of the system can also be utilized, the process is not a Markov process. The optimum Bayesian policies are derived and the properties of the resulting process axe studied. Also, the stochastic processes are simulated and the probability of absorption, the mean time to absorption and the average proportion of the retrograde motion are approximated.


1969 ◽  
Vol 6 (3) ◽  
pp. 584-593 ◽  
Author(s):  
T. C. T. Kotiah ◽  
J. W. Thompson ◽  
W. A. O'N. Waugh

SummaryThe use of Erlangian distributions has been proposed for the approximation of more general types of distributions of interarrival and service times in single-server queueing systems. Any Erlangian approximation should have the same mean and variance as the distribution it approximates, but it is not obvious what effect the various possible approximants have on the behaviour of the system. A major difference between approximants is their degree of skewness and accordingly, numerical results for various approximants are obtained for (a) the mean time spent by a customer in a simple single-server system, and (b) the mean queue length in a system with bulk service. Skewness is shown to have little effect on these quantities.


2013 ◽  
Vol 1 (2) ◽  
pp. 28
Author(s):  
Dite Ardian ◽  
Adian Fatchur Rochim ◽  
Eko Didik Widianto

The development of internet technology has many organizations that expanded service website. Initially used single web server that is accessible to everyone through the Internet, but when the number of users that access the web server is very much the traffic load to the web server and the web server anyway. It is necessary for the optimization of web servers to cope with the overload received by the web server when traffic is high. Methodology of this final project research include the study of literature, system design, and testing of the system. Methods from the literature reference books related as well as from several sources the internet. The design of this thesis uses Haproxy and Pound Links as a load balancing web server. The end of this reaserch is testing the network system, where the system will be tested this stage so as to create a web server system that is reliable and safe. The result is a web server system that can be accessed by many user simultaneously rapidly as load balancing Haproxy and Pound Links system which is set up as front-end web server performance so as to create a web server that has performance and high availability.


2011 ◽  
Vol 23 (1) ◽  
pp. 124-159 ◽  
Author(s):  
Terry Elliott

Stochastic models of synaptic plasticity propose that single synapses perform a directed random walk of fixed step sizes in synaptic strength, thereby embracing the view that the mechanisms of synaptic plasticity constitute a stochastic dynamical system. However, fluctuations in synaptic strength present a formidable challenge to such an approach. We have previously proposed that single synapses must interpose an integration and filtering mechanism between the induction of synaptic plasticity and the expression of synaptic plasticity in order to control fluctuations. We analyze a class of three such mechanisms in the presence of possibly non-Markovian plasticity induction processes, deriving expressions for the mean expression time in these models. One of these filtering mechanisms constitutes a discrete low-pass filter that could be implemented on a small collection of molecules at single synapses, such as CaMKII, and we analyze this discrete filter in some detail. After considering Markov induction processes, we examine our own stochastic model of spike-timing-dependent plasticity, for which the probability density functions of the induction of plasticity steps have previously been derived. We determine the dependence of the mean time to express a plasticity step on pre- and postsynaptic firing rates in this model, and we also consider, numerically, the long-term stability against fluctuations of patterns of neuronal connectivity that typically emerge during neuronal development.


1969 ◽  
Vol 6 (03) ◽  
pp. 584-593 ◽  
Author(s):  
T. C. T. Kotiah ◽  
J. W. Thompson ◽  
W. A. O'N. Waugh

Summary The use of Erlangian distributions has been proposed for the approximation of more general types of distributions of interarrival and service times in single-server queueing systems. Any Erlangian approximation should have the same mean and variance as the distribution it approximates, but it is not obvious what effect the various possible approximants have on the behaviour of the system. A major difference between approximants is their degree of skewness and accordingly, numerical results for various approximants are obtained for (a) the mean time spent by a customer in a simple single-server system, and (b) the mean queue length in a system with bulk service. Skewness is shown to have little effect on these quantities.


1996 ◽  
Vol 75 (05) ◽  
pp. 731-733 ◽  
Author(s):  
V Cazaux ◽  
B Gauthier ◽  
A Elias ◽  
D Lefebvre ◽  
J Tredez ◽  
...  

SummaryDue to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.


2020 ◽  
Vol 7 (10) ◽  
pp. 875-894
Author(s):  
Yeni Yuliana

Abstract The internet can be made as a way to transfer knowledge from lecturers to students, while Learning that utilizes the internet is one of the E-Learning Learning media. E-learning is distance learning that utilizes computer technology or computer networks or the Internet E-learning, so that it can enable the learning process through computers in their respective places without having to physically go to attend classes or lectures in class, Systems e-learning learning is a new way of teaching and learning. E-learning as a special learning media PAI courses provide a very important role and a large function in the course because so far there are many shortcomings and weaknesses such as the limitations of space and time in the teaching and learning process through E-learning which prioritizes the efficiency of learning so students get full teaching even though they do not have to be face to face, can also be accessed anywhere, anytime, according to the assignments given by the lecturer usually scheduled with a specified deadline. The development of education towards e-learning is a must so that the quality standards of education can be improved, E-learning is one of the uses of internet technology in the delivery of learning and its broad reach. E-learning can also be an answer to a health problem that is Pandemic Corona (Covid-19) which is very influential also in every aspect of life, especially in education.Keywords: Effectiveness, Utilization, Islamic Religious Education, E-Learning, Covid 19. Abstrak Internet dapat dijadikan cara untuk mentransfer ilmu pengetahuan dari Dosen kepada mahasiswa/mahasiswi. Adapun Pembelajaran yang memanfaatkan internet salah satunya adalah media pembelajaran E-Learning. E-learning adalah pembelajaran jarak jauh (distance learning) yang memanfaatkan  teknologi komputer atau jaringan komputer atau internet E-learning, sehingga dapat  memungkinkan proses pembelajaran melalui komputer di tempat mereka  masing– masing tanpa harus secara fisik  pergi  mengikuti pelajaran atau pun  perkuliahan di kelas,  Sistem pembelajaran e-learning adalah cara baru dalam proses belajar mengajar. E-learning  sebagai   media pembelajaran khususnya mata kuliah PAI memberikan  peran   sangat   penting  dan fungsi yang besar pada mata kuliah tersebut karena selama  ini terdapat banyak  kekurangan  dan kelemahan seperti keterbatasan ruang dan waktu dalam  proses belajar  mengajar melalui E-learning yang  mengedepankan keefisienan dalam belajar sehingga  mahasiswa mendapat pengajaran yang penuh meski tidak harus bertatap muka, juga bisa di akses di mana saja, kapan saja,  sesuai dengan tugas yang diberikan oleh dosen biasanya terjadwal dengan  batas  waktu  yang  di tentukan. Pengembangan  pendidikan menuju e-learning merupakan suatu keharusan agar standar mutu pendidikan dapat ditingkatkan,  E-learning merupakan salah satu penggunaan teknologi internet dalam penyampaian  pembelajaran  serta  jangkauannya yang luas. E-learning  juga dapat menjadi jawaban dari suatu permasalahan kesehatan yaitu Pandemi Corona (Covid-19) ini yang sangat berpengaruh juga pada setiap aspek kehidupan terutama bidang pendidikan.Kata kunci  :  Keefektifitas, Pemanfaatan, Pendidikan Agama Islam,  E-Learning, Covid 19.  


2020 ◽  
Vol 4 (3) ◽  
pp. 551-557
Author(s):  
Muhammad zaky ramadhan ◽  
Kemas Muslim Lhaksmana

Hadith has several levels of authenticity, among which are weak (dhaif), and fabricated (maudhu) hadith that may not originate from the prophet Muhammad PBUH, and thus should not be considered in concluding an Islamic law (sharia). However, many such hadiths have been commonly confused as authentic hadiths among ordinary Muslims. To easily distinguish such hadiths, this paper proposes a method to check the authenticity of a hadith by comparing them with a collection of fabricated hadiths in Indonesian. The proposed method applies the vector space model and also performs spelling correction using symspell to check whether the use of spelling check can improve the accuracy of hadith retrieval, because it has never been done in previous works and typos are common on Indonesian-translated hadiths on the Web and social media raw text. The experiment result shows that the use of spell checking improves the mean average precision and recall to become 81% (from 73%) and 89% (from 80%), respectively. Therefore, the improvement in accuracy by implementing spelling correction make the hadith retrieval system more feasible and encouraged to be implemented in future works because it can correct typos that are common in the raw text on the Internet.


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