Physical Carrier Research Articles

A Survey of Adaptive Carrier Sensing Mechanisms for IEEE 802.11 Wireless Networks

This survey provides a comprehensive review of existing physical carrier sensing enhancements for IEEE 802.11 wireless networks. The original physical carrier sensing mechanism, used by wireless stations to gain access to the medium, is limited. Consequently, IEEE 802.11 networks are vulnerable to the presence of hidden and exposed nodes. Such nodes can significantly decrease system performance by increasing the collision rate and decreasing the channel spatial reuse. The value of the physical carrier sensing threshold is a key factor influencing the presence of hidden and exposed nodes in a wireless network. Several enhancements have been proposed in the literature, which attempt to mitigate the loss in performance caused by the limited carrier sensing. Firstly, the notion of an optimum carrier sensing threshold has been studied, and results indicate that it can be tuned to an optimum value. Building on the positive early results, further work was performed to develop mechanisms that dynamically adjust the threshold according to varying network conditions. This article presents an in-depth survey of the existing literature in the area, detailing the various approaches and their efficacy in addressing the problem of hidden and exposed nodes (and consequently increasing performance). It offers a comparison of the techniques, by evaluating the models, limitations, assumptions, and performance gains.

How can i find a doggy book?: Children's cognitive processes of physical characteristics of books

How can i find a doggy book?: Children's cognitive processes of physical characteristics of books

Endogenous oscillations of electric potential difference in the cambial region of the pine stem. II. Possible involvement of the oscillations in xylogenesis

Direct and indirect interrelations between xylogenic processes and the endogenous electric potential difference (PD) oscillations generated in the cambial region of isolated tissue blocks from pine trunks were investigated. The frequency of transient PD changes varied during the season and displayed three minima which were concurrent with periods of initiation and termination of cambial activity and with the time of transition from early- to late-wood production. The oscillations were damped by TIBA - an inhibitor of polar auxin transport and stimulated by IAA, but only when the hormone was supplied to the apical end of the tissue block. This suggests that the polar transport of auxin may be involved in generation of the transient PD changes. Results of 2-channel recordings in one tissue block suggest that a part of the recorded oscillations (10-25 %) exhibit coordination in space and time: a wave-like pattern along the trunk axis is created by PD changes. The pattern might be a physical carrier of information coordinating processes of growth and differentiation in distant parts of the tree.

DUAL SURFACE-FUNCTIONALIZED SUPERPARAMAGNETIC JANUS NANOCOMPOSITES OF POLYSTYRENE/Fe3O4@SiO2 VIA A ONE-POT MINIEMULSION METHOD

We report a straightforward synthesis of superparamagnetic Janus Polystyrene/ Fe 3 O 4@Silica ternary nanocomposites via a one-pot miniemulsion approach. The nanocomposites are dual functionalized simultaneously on the same physical carrier, with the carboxyl groups on the polystyrene surface while the silica region is functionalized with silano. With such a unique dual surface structure, it is possible to selectively functionalize multiple surfaces of a single carrier nanoparticle. Multifunctionality can be more readily achieved by this approach for biomedical applications. In this experiment, Doxorubicin is loaded on the silica region, as the model drug, for controlled release via a pH-responsive triggering mechanism. Meanwhile, the polystyrene surface is available for conjugating cancer-specific markers, which is needed for cell targeting. Also discussed are the reaction mechanisms and the key processing parameters in the synthesis of Polystyrene/ Fe 3 O 4@Silica nanocomposites.

Zenona Fajfera teoria liberatury

The main purpose of this article is presentation and critical analysis of Zenon Fajfer’s notion “liberatura “liberture”” (developed also by Katarzyna Bazarnik). The conception of liberature as “total literature in which the text and the space of a book constitute an inseparable whole” is known since1999 inPolish Literary studies and now is a wide discussed subject abroad. Being a new idea, after all, it concerns also very old (existing from the beginnigs of letters and literature, for example: visual poems of Simmias of Rhodes (of 325 BC) and Theocritus (of III BC)) fenomena. The conception of liberature was invented for the sake of the Oka-leczenie [‘Eyes-ore’], the first book created by Fajfer and Bazarnik (since 1988 until 2009) and described by them as very sample of 'liberature'. Authors just don't made another example of art book or book-art, but literary work of art including sphere of iterests and meaning with “phisical elements”, “bookish elements” or “editorial formality”. Flank of transfer from meanings of used words here subsequent and very important was (away from conventions) semantically carrying manner of book edition as the way performing. Term „liberature” Fajfer originates not only from Latin: “līběr, līběra, līběrǔm” = ‘liberty’ , but also from “līběr, lībri” = ‘book’ and “lībra, lībrae” = ‘Libra’ (‘scales’). Freedom in “liberature” means liberation from rules and publishing conventions. It has to indicate capability to involving publishing form to construction of integrity of transfer to significant integrity of text with its unindifferent physical carrier “book”. Then it indicates necessity of selection of – weighing word “weight” also in respect visual, quantitative or respect letter composition, behavior of proportions between text, image, the way of pagination etc. The Fajfer’s concept, continuously obtained, inclines for assigning question, among others, about mutual rates of balks literature but liberature, liberature but visual arts, about place liberature in literature, about still actual definition of book.

Impact of physical and virtual carrier sensing on the route discovery mechanism in noisy MANETs

In cellular consumer devices, one of the limiting factors for efficiency is that of overhead on the network layer that effects on the performance of the network. A substantial design issue is that, with cellular consumer devices, the discovery phase of the routing process, when attempting to establish a mobile ad hoc network, a high demand is placed on the network layer. Hence, a challenge for the designer is to reduce this demand, thus increasing overall device availability. Routing algorithms, and hence the performance of the networks are adversely affected by inefficient carrier sensing methods which can lead to increasing packet loss within the network environment. In this paper, the effect of physical and virtual carrier sensing on the route discovery mechanism has been identified and this paper suggests that choosing a suitable carrier sensing threshold in a high density and noisy mobile ad hoc network yields a better performance than if the default value is used1.

CYBERSPACE DEVELOPMENT AND INFORMATION SECURITY

Aim of this article is significant improving the quality of services delivered by the software, hardware, and cyberspace networks, as well as reducing the operation cost through the creation of infrastructures IP, providing user-friendly operation, testing and removal of non-functional destructive components. A model of evolving cyberspace is proposed, where the subjects are interacting processes or phenomena with physical carrier in the form of computer systems and networks. The universal nonarithmetic model for structural estimating the relation of two objects in cyberspace is developed. It is designed for recognition the set-theoretic or vector interaction of objects. The architecture of multimatrix processor is created, focused on increasing the performance of embedded functional failure diagnosis in software or hardware. Infrastructures IP for protecting software against malicious code and verification of digital systems are described. The structural model for recognizing the destructive patterns based on the relationships of the input pattern, standards and similarity criteria.

Physical Therapist and Carrier Design for Women

Physical Therapist and Carrier Design for Women

Advanced warpage characterization for FOWLP

Current standards for silicon wafers shape characterization use simple metrics. Warpage and bow are computed as the mean surface wafer height range or the mean surface wafer center height, respectively [1]. These metrics are valid for silicon wafers because of their homogenous and linear thermomechanical properties [2]. In fan-out wafer level package (FO-WLP), embedded Wafer Level Ball Grid Array in specific (eWLB), the use of epoxy mold compound that works both as the physical carrier of the dies and as the base of second level connections has a major impact on the overall macroscopic behavior of the wafer, inducing shapes that do not follow a simple bended or bowed wafer, impacting wafer processability [3]. Warped wafers can affect device performance, reliability, and linewidth control in various processing steps [3]. Early detection will minimize cost and processing time. In our research, we present a solution for wafer characterization in FO-WLP by increasing the information vector that one obtains from standard automated non-contact scanning equipment. For this, we defined wafer shape and wafer ratio as the two new metrics besides warpage, creating a three dimensional vector that can be used to compare and evaluate wafers in high volume production or even single wafer analysis. This is a major improvement over previously used approaches, in which only the average warpage is considered. These metrics were determined by the developed numeric algorithm and their validity was demonstrated through the use of different production conditions, wafer constructions and production monitoring. The proposed approach requires no extra processing steps and time, as compared to conventional off-line methods. Experimental results demonstrate its feasibility and repeatability. This methodology was successfully used in the field and proved to be of high value when evaluating wafer geometrical requirements for both product development and process monitoring.

THE USE OF USB-DRIVE FOR COLLECTION OF BIOMEDICAL DATA IN MEDICAL ELECTRONIC PASSPORT

This article reviews the storage media which are nowadays. The use of USB-drive with two-layer protection system has been proposed as a physical carrier of medical electronic passport.

Electrochemistry of organometallic lyotropic chromonic liquid crystals

Two aqueous lyotropic chromonic liquid crystals made from nickel(II) or copper(II) phthalocyananine tetrasulfonic acid tetrasodium salt are prepared with characterisation through optical polarising microscopy, X-ray diffraction and conductivity. These consist of ordered molecular aggregates of ~10 molecules, held together by π–π stacking. Electrochemistry within these dynamic, optically anisotropic columnar systems reveals that diffusion (physical transport or charge carrier hopping) can occur within two-dimensions.

Characteristics of InGaP/InGaAs pseudomorphic high electron mobility transistors with triple delta-doped sheets

Fundamental and insightful characteristics of InGaP/InGaAs double channel pseudomorphic high electron mobility transistors (DCPHEMTs) with graded and uniform triple δ-doped sheets are coomprehensively studied and demonstrated. To gain physical insight, band diagrams, carrier densities, and direct current characteristics of devices are compared and investigated based on the 2D semiconductor simulator, Atlas. Due to uniform carrier distribution and high electron density in the double InGaAs channel, the DCPHEMT with graded triple δ-doped sheets exhibits better transport properties, higher and linear transconductance, and better drain current capability as compared with the uniformly triple δ-doped counterpart. The DCPHEMT with graded triple δ-doped structure is fabricated and tested, and the experimental data are found to be in good agreement with simulated results.

Manipulation of entanglement and preparation of quantum states for moving two-atom and the light field via intensity-dependent coupling

In this paper, the Tavis-Cummings model is generalized to simultaneously consider the atomic motion and the field via intensity dependent coupling. Under the conditions of vacuum field, weakly and strongly coherent field, the entanglement evolution properties of two-atom-field and two-atom-two-atom are investigated using atomic reduced entropy and concurrence, respectively. According to evolution characteristics above, we prepare the W-class states of two-atom-field, two-atom Bell state, fidelity state of Bell-state atoms, single-photon state, two-photon state and stable number-states of field by selecting the interaction time of the two-atom-field, selecting the entanglement factor of the two-atom, regulating the field-mode structure parameter, controlling the probability amplitude of pure state of the system and selective measurement. The manipulation of two-atom Bell state sudden generation and its maintenance in a limited time, the formation of periodic quantum echo of Bell-state atoms and the continuous fidelity of Bell-state atomic information are achieved. The results show that the system has a powerful function of quantum information, and provide the physical carrier and theoretical parameters for experimental implementation of quantum information processing.

CSMA 기반 무선 애드 혹 네트워크에서 반송파 감지 반경의 반복적 근사 기법

최근 CSMA가 많은 무선 환경에서 적용됨에 따라 CSMA 기반의 우선 네트워크의 성능을 높이기 위한 다양한 통계적 분석이 수행되고 있다. 그러나 이러한 노력에도 불구하고 여전히 CSMA가 가지고 있는 작위적 특성은 네트워크의 분석을 어렵게 만들고 있다. 기존의 많은 연구들은 대규모 CSMA 네트워크의 통계적 분석에서 노드의 반송파 감지 기능을 표현하기 위해 반송파 감지 반경을 도입하여 사용해 왔다. 그러나 반송파 감지 반경은 노드의 전송 여부에 따른 노드 간 간섭효과를 고려하지 않기 때문에 간섭이 큰 채널 환경에 적용되는 경우 분석 오류를 피하기 어렵다. 본 연구에서는 이러한 문제점을 해결하고자 노드 간 간섭효과를 고려한 물리적 모델 기반의 반송파 감지 반경을 유도하는 알고리즘을 제안한다. 이를 위해 대규모 CSMA 네트워크에서의 반송파 감지 동작 특성과 이에 따른 간섭효과를 분석하고, 분석 결과를 토대로 물리 모델에 근사된 반송파 감지 반경을 찾기 위한 감지 반경의 반복적 근사 기법을 제안한다. 제안된 알고리즘의 적합성을 확인하기 위해 모의실험을 통해 제안된 감지 반경을 이용해 다양한 채널 환경에서 유도된 총 간섭 모델의 정확성을 비교 분석하였다. Recently, as CSMA technique has been increasingly adopted in various wireless networks, extensive researches to analyze the statistical characteristics of CSMA-based wireless networks have been done. Despite the ongoing efforts, there still remain many difficulties in the analysis because of unexpectable operational behavior of CSMA. Previous literature studying CSMA networks used the concept of the carrier sensing radius to reflect the carrier sensing function. However, since the carrier sensing radius based on the protocol model is not affected by the aggregate interference from other nodes, the derived statistical models cannot avoid approximation errors especially if the network is under high interference. In this paper, we propose an algorithm to derive the carrier sensing radius considering the physical model, where the carrier sensing radius reflecting the aggregate interference is found. For the purpose of this, we analyze the aggregate interference model and the behavior of CSMA function. Based on the analysis, we propose an iterative approximation algorithm for the physical carrier sensing radius. Extensive simulations and results show that the proposed algorithm can contribute to considerably reduce the statistical modeling error of a CSMA network under various channel conditions.

Rotational Listening Strategy for IEEE 802.15.4 Wireless Body Networks

In recent years, interests in the application of wireless body network (WBN) have grown considerably. Wireless body sensor nodes assume deploying a stationary sensor network over a human body area. Among the well-known specifications, IEEE 802.15.4 originally designed for low-power, low-rate, and short-distance wireless personal area networks (WPANs) has become one of the promising candidates for interconnections between wireless sensor nodes. IEEE 802.15.4 uses a modified carrier-sense multiple access with collision avoidance (CSMA/CA) MAC protocol to access channel for transmission data; however, it suffers from inefficient channel utilization because the physical carrier sensing is only performed after the backoff period. In this paper, a rotational listening strategy (RLS) is proposed to increase the rate of successful transmission for WBN. The channel access period is logically partitioned into a number of mini-slots that are individually allocated to nodes. In this case, inefficient channel utilization and collisions can be resolved simultaneously, meanwhile retaining fairness criterion. In addition, an enhanced RLS is proposed to handle the load unbalance situation among nodes. This paper also provides a coexistence solution for the situation where there are nodes without RLS associating with an RLS-enabled WSN. Analytical and numerical simulations are both studied to evaluate the performance of RLS. Both results illustrate that RLS indeed improves transmission efficiency as well as energy consumption.

The case for SIMO random access in multi-antenna multi-hop wireless networks

In this paper, we demonstrate that multiple concurrent asynchronous and uncoordinated Single-Input Multiple-Output (SIMO) transmissions can successfully take place even though the respective receivers do not explicitly null out interfering signals. Hence, we propose simple modifications to the widely deployed IEEE 802.11 Medium Access Control (MAC) to enable multiple non-spatially-isolated SIMO sender-receiver pairs to share the medium. Namely, we propose to increase the physical carrier sense threshold, disable virtual carrier sensing, and enable message-in-message packet detection. We use experiments to show that while increasing the peak transmission rate, spatial multiplexing schemes such as those employed by the IEEE 802.11n are highly non-robust to asynchronous and uncoordinated interferers. In contrast, we show that the proposed multi-flow SIMO MAC scheme alleviates the severe unfairness resulting from uncoordinated transmissions in 802.11 multi-hop networks. We analytically compute the optimal carrier sense threshold based on different network performance objectives for a given node density and number of receive antennas.

Improving the performance of power-aware multi-rate IEEE 802.11 in multihop wireless networks

In multihop, multi-rate wireless networks, simultaneous transmissions can interfere with one another to impair the transmission quality and prevent correct frame reception. Achieving high network performance (e.g. throughout and energy consumption) in such networks therefore requires a balance between the spectrum spatial reuse and the transmission quality. To achieve this trade-off, a decentralised control algorithm is proposed that allows a sender–receiver pair, using the IEEE 802.11 four-way access method, to dynamically adjust the transmit power and rate for their frames according to the level of interference in the network. Specifically, the scheme is based on the interplay between two approaches: physical carrier sensing and virtual carrier sensing approach to achieve this optimal trade-off. The algorithm outlines the rules for performing power and rate assignment so that higher performance is obtained. A realistic analytical model is presented to study the performance of the proposed heuristic; analytical results show that the algorithm proposed by the authors, indeed, finds the balance between spatial reuse and transmission quality through its appropriate search for the suitable transmission parameters. Simulation results for different topologies are used to demonstrate the significant throughput and energy gains that can be obtained by the proposed scheme.

Colloidal Carrier Systems for Transcutaneous Immunization

Recently, the skin has emerged as a potential alternative route for non-invasive delivery of vaccine. It has been recognized as a highly immune-reactive tissue containing an abundance of antigen presenting cells, especially within the epidermis. Transcutaneous immunization, introduction of antigen through topical application onto the intact skin, has many practical merits compared to injectable routes of administration. It combines the advantages of needle-free delivery while targeting the immunologically rich milieu of the skin. This simple and non-invasive immunization procedure elicits systemic and cell mediated immune responses and therefore, it provides a viable and cost-effective strategy for disease prevention. Various strategies i.e physical, chemical and novel carrier systems can be explored for trancutaneous immunization. Specially designed vaccine carrier systems are attracting immense attention and these could be potential module for non-invasive antigen delivery. The review covers topical delivery consideration in brief followed by an insight into various novel delivery systems for transcutaneous vaccine delivery.

Innovative Examples of Product Design Based on Material

Material is physical basis and carrier of design, which is a very important part of product design. On the one hand, designers can make innovations on traditional shape through using new materials; on the other hand they can make it from new materials and techniques for reference. The author put forward a subject of “designing for sitting” in teaching, asked the students to think from the perspective of material and finish the prototype, good effect has been obtained through this training. The pictures used in this paper were schoolwork of partial students who major in art design of North China Electric Power University, thanks for their passion and creativity.

On the Record: The Philosophy of Recording. An Introduction

At the Theoretical Archaeology Group (TAG) conference in Durham in December 2009 I organised a session on the philosophy of recording, and the three articles presented here originated in that discussion. The aim of the session was to consider some fundamental questions about the recording that archaeologists undertake but which are often overlooked, and think about these in a theoretical way. These questions included: Why do we choose to record the sites, monuments and artefacts that we do? Why do we select the units of information we choose to record about them? How have the things we record and the attributes recorded changed over time? How can the adoption of a reflexive approach enable us to assess the recording choices we make and inform those that will be made in the future? What do these recording choices tell us about archaeology and wider society over time? Can something as intangible as a database record or a digital photograph be considered as an artefact and studied as material culture? How are new technologies changing recording and adding to the material available for study, which will form the historic documents of the future? The first two of these questions are decisions that archaeologists have been making since the earliest origins of the discipline, often without a passing thought. It is not very often that we pause to analyse them at a theoretical level. As recording has developed we have been very good at categorizing, making inventories and constructing ontologies to describe the past around us, but less good about asking why we do so in the way we do. The three articles presented here address some of the fundamental questions posed by the original session abstract. Geographically they cover the whole of Great Britain, considering the legacy of paper records in England, scheduling in Wales and the <em>Proceedings of the Society of Antiquaries of Scotland. My own contribution to the session deals with the nature of information and how this can transcend the medium on which it is represented, and be treated as an item of material culture divorced from its physical carrier. One of the areas of record concerns scheduling, and Oliver Davis looks in more detail at how this is handled in Wales. The emphasis here is on the spatial relationship of the sites and the relationship of the concept to more modern interpretations of landscape. The contribution from Jonathan Bateman and Stuart Jeffrey looks at past editions of the Proceedings of the Society of Antiquaries of Scotland and how metadata on papers can be generated to aid retrieval of information. There are some interesting links to be seen between these contributions. All three demonstrate the use that can be made of old records of the historic environment and how information technology makes it possible to interrogate and disseminate the data in ways its originators could never have imagined. One aspect of this is how this interrogation enables a reflexive interpretative assessment of the data to be undertaken in order to reveal biases in the sample. This is of more than just academic interest, as it is important when planning future programmes of work. Furthermore, Davis includes a reference to the monumentality of a site which compares with the assessment from the contribution on the materiality of information. Bateman and Jeffrey also refer to the idea that language can be seen as material culture, which itself links to the consideration of the analysis of information by the ADS through natural language processing. The common thread across the articles is how the recording, whether through designation, on paper, digitally or in a journal, influences our perception of a site. The session was organised in conjunction with the Information Management Special Interest Group of the Institute for Archaeologists (IfA IMSIG). I would like to thank my fellow contributors to this themed section, including Sarah May and Dan Hull who presented at the original TAG session but were unable to contribute here. I would also like to thank Professor Julian Richards who acted as the discussant at TAG and suggested publication in Internet Archaeology. I hope the reader will find this collection of articles interesting and thought-provoking.