scholarly journals THE TRANSPORT LAYER OF THE ISO/OSI MODEL IN COM­PUTER NETWORKS

Author(s):  
KOSTIUK Yuliia ◽  
SHESTAK Yaroslav

Background. The transport layer is designed to deliver data without errors, losses and duplication in the order in which they were transmitted. It provides data transfer between two applications with the required level of reliability. Transport layer protocols, which guarantee reliable data delivery, establish a virtual connection before data exchange and resend segments in case of loss or damage. The aim of the study was to determine the role of transport security protocols in computer networks. Materials and methods. To achieve the goal, the study used statistical analysis and a systematic approach. Results. TCP provides reliable message transmission through the formation of logical connections, while allowing peers on the sending computer and the receiving computer to support data exchange in duplex mode. It also has the ability to seamlessly send a byte stream generated on one of the computers to any other computer connected to the network.In addition, TCP controls the connection load, UDP does not control anything but the integrity of the received datagrams. Conclusion. The difference between TCP and UDP is the so-called "delivery guarantee". TCP requires a response from the client to whom the data packet is delivered, confirmation of delivery, and for this he needs a pre-established connection. TCP is also considered reliable, unlike UDP, which is called "unreliable datagram protocol". TCP eliminates data loss, duplication and shuffling of packets, delays, UDP allows all this, and it does not need a connection to work., as a result of which the data is transferred on UDP, should manage received, even with losses.

10.29007/h7cg ◽  
2018 ◽  
Author(s):  
Geerija Lavania ◽  
Preeti Sharma ◽  
Richa Upadhyay

The wireless sensor network is the network that has large number of sensor nodes that are connected to each other. The wireless nodes sense the event and forward packets to the destination node. A transport layer handles congestion and packet loss recovery for reliable data transfer in WSN. There exist several protocols at the transport layer in WSN for reliable data transfer like ESRT, ATP, Tiny TCP/IP, PORT, CTCP, RTMC, DCDD, RETP etc. Each protocol has its merits and demerits. Traditional network uses TCP and UDP protocol at the transport layer. In WSN, these are not suitable. In this work, the TCP, SCTP and MPTCP are compared in the wireless sensor network environment. The wireless network with packet loss is considered. From the comparative analysis, we get the result that MPTCP gives the better performance than TCP and SCTP in the wireless sensor network.


1999 ◽  
Vol 38 (04/05) ◽  
pp. 321-325 ◽  
Author(s):  
R. Schweiger ◽  
U. Altmann ◽  
M. Holena ◽  
B. Blobel ◽  
J. Dudeck ◽  
...  

AbstractWhen data are transmitted between electronic patient record (EPR) systems, we can distinguish several tasks. One task is the definition of structure and semantic content of the data in a message structure. Another task is the mapping of the sending EPR’s structure to this message structure. A third task is the mapping of the message structure to the receiving EPR’s structure. We describe an approach, which distinguishes clearly between these different tasks and activities. Using this approach we have implemented a data transfer procedure between a cancer registry application and a middleware for healthcare information systems. Our experience showed that the proposed systematic approach helped identify problems for data transfer in an early design phase. It also allowed us to limit modifications of the data exchange procedure to certain tasks or activities when one of the EPR applications was updated. In the end, we could even exchange the underlying message format without having to reimplement the complete interface.


2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Astika Ayuningtyas ◽  
Asih Pujiastuti ◽  
Anggraini Kusumaningrum ◽  
Nurcahyani Dewi Retnowati ◽  
Gabriel Naka Sorateleng

Increasing human productivity accompanied by increasingly advanced developments has an impact on the need for faster and easier communication and data exchange, one of which is using a mobile smartphone. ReResik application is an application that is used to report the accumulation of garbage. Garbage accumulation is a problem that is often encountered, one of which is in Gunungkidul tourism objects, so there needs to be a solution to solve this problem. One solution is to utilize Global Positioning System (GPS) and Firebase technology to create a waste reporting application. The use of GPS can make it easier to report the accumulation of garbage in a place by utilizing geo tagging technology and the complexity of the features found in Firebase provide user convenience both in terms of application development and the use of features in applications that can facilitate reporting and recipients of waste reports. All functions in the ReResik Application run according to design. Tests in the field can show the location of the accumulation of waste with photos sent with the difference in the accuracy of the location where the report of accumulation of waste occurs 1.38 meters from the location point sent by the application. The average data transfer capability of the ReResik Application upload is 1161.8 ms for the reporting section and 1004.2 ms for the cleaning staff. Functional testing of photos uploaded to Firebase has gone through the process of automatically compressing photos with an average value percentage of 61.22% of the uploaded photo size.


Author(s):  
Árpád Huszák ◽  
Sándor Imre

Numerous protocols were introduced in the transport layer, which can be very different depending on the provided services. Beside the traditional TCP and UDP, new transport protocols (SCTP, DCCP) have appeared in recent years to overcome limitations of the conventional protocols. The unique features of SCTP like multihoming and multistreaming make this protocol very attractive for reliable data delivery of streams, even in a mobile environment. It can be also used for applications where monitoring and detection of loss is required. SCTP is the only transport protocol that is able to manage mobility issues and handle handovers in the transport layer. The multihoming feature allows an endpoint of a SCTP association to be mapped to multiple IP addresses, and change the delivery path according to the link conditions. The handover process is hardly influenced by several protocol parameters that can be adjusted by the user. The effects of different protocol settings are investigated in details in this chapter. We have studied the performance of multihomed SCTP hosts through experimental studies in an integrated heterogeneous environment. SCTP will also play a significant role in future LTE–EPS architecture, because it can also be used for core network signaling purposes, not just for user data delivery.


Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.


1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences


Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.


Author(s):  
Brian Willems

A human-centred approach to the environment is leading to ecological collapse. One of the ways that speculative realism challenges anthropomorphism is by taking non-human things to be as valid objects of investivation as humans, allowing a more responsible and truthful view of the world to take place. Brian Willems uses a range of science fiction literature that questions anthropomorphism both to develop and challenge this philosophical position. He looks at how nonsense and sense exist together in science fiction, the way in which language is not a guarantee of personhood, the role of vision in relation to identity formation, the difference between metamorphosis and modulation, representations of non-human deaths and the function of plasticity within the Anthropocene. Willems considers the works of Cormac McCarthy, Paolo Bacigalupi, Neil Gaiman, China Miéville, Doris Lessing and Kim Stanley Robinson are considered alongside some of the main figures of speculative materialism including Graham Harman, Quentin Meillassoux and Jane Bennett.


2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>


Author(s):  
S.A. Kirillina ◽  
A.L. Safronova ◽  
V.V. Orlov

Аннотация В статье изучены общие и специфические черты идейных воззрений, пропагандистской риторики и политических действий представителей халифатистского движения на Ближнем Востоке и в Южной Азии. В ретроспективном ключе прослеживается эволюция представлений о сущности и необходимости возрождения института халифата в трудах исламских идеологов, реформаторов и политиков Джамал ад-Дина ал-Афгани, Абд ар-Рахмана ал-Кавакиби, Мухаммада Рашида Риды, Абул Калама Азада. Внимание авторов сосредоточено на общественно-политических дискуссиях 2030-х годов XX столетия, а также на повестке дня халифатистских конгрессов и конференций этого периода. На них вырабатывались первые представления современников о пост-османском формате мусульманского единства и идейно-политической роли будущего халифата. Авторы демонстрируют различие между моделями реакции мусульман Ближнего Востока и Южной Азии на упразднение османского халифата республиканским руководством Турции. Установлена многоаспектная взаимосвязь между халифатистскими ценностями, проосманскими настроениями и формами самоотождествления, которые сложились в арабских и южноазиатских обществах. Отдельно намечено соотношение между подъемом халифатистских настроений и радикализацией антиколониальных действий мусульман Индостана.Abstract The article deals with analysis of common and specific features of ideas, propaganda, rhetoric and political actions taken by representatives of the movement for defense of the Caliphate in the Middle East and South Asia. The retrospection showing the transformation of conception of the Caliphate and the necessity of its revival in the works of eminent ideologists and politicians of the Muslim world Jamal al-Din al-Afghani, Abd al-Rahman al-Kawakibi, Muhammad Rashid Rida and Abul Kalam Azad, is also given in the article. The authors also focus on the social and political discussions of the 1920s 1930s, as well as on the agenda of Caliphatist congresses and conferences of this period. They helped to elaborate the early representations of post-Ottoman pattern of the Muslim unity and the ideological and political role of the future Caliphate. The authors demonstrate the difference between the forms of reaction of Muslims in the Middle East and South Asia to the repudiation of the Caliphate by the Republican leaders of Turkey. The article establishes a multi-aspect interaction between the Caliphatist values and forms of self-identification, emerged in Arab and South Asian societies. The correlation between the rise of Caliphatist attitudes and radicalization of anti-colonial actions of South Asian Muslims is also outlined.


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