WorldWideScience

Sample records for base ad indicatori

  1. Sea level variations along the Latium coastal region by archaeological indicators; Variazioni del livello del mare nel tardo olocene (ultimi 2500 anni) lungo la costa del Lazio in base ad indicatori geo-archeologici. Interazioni fra neotettonica, eustatismo e clima

    Energy Technology Data Exchange (ETDEWEB)

    Leoni, G.; Dai Pra, G. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1997-07-01

    Evidence of ancient sea level is widely represented along the coast of Latium (central Italy) by geological indicators related to last interglacial highstands and by archaeological indicators such as remains of maritime buildings from different epochs. Pleistocene coastlines were displaced at different elevations by structural discontinuities whose features are situated along the lower sections of the rivers Fiora, Mignone and Astura. The greater uplifts (up to 0.2 mm/yr) are localised near the main volcanic centres. Tectonic activity seems to end towards the end of last interglacial ({approx} 80 kyr BP) when the whole area reaches its geological stability, except for the Pontine and Fondi plains which are still subsiding. The measurement, interpretation and correction for the neotectonic effect of nearly 160 archaeological indicators suggests a rate of eustatic rise of 3.9 mm/yr between IV and I century BC and of 1.2 mm/yr between I and II century AD; sea level in the year zero was 34 cm lower than at present. The observed eustatic change reflects with high precision the climatic change corresponding to the roman warm epoch, and allows to quantify its magnitude. Comparison of historical and instrumental data (Genoa`s tide-gauge 1884-1971) points out that the eustatic change of the last century seems to be dominated by a natural climatic trend when compared to the worrying signals of global heating pointed out by other climatic indicators (increase of CO{sub 2} and CH{sub 4} glaciers` melting, etc.) which are affected by greater local disturbs.

  2. Grandi Eventi: indicatori di classificazione e incidenza sui sistemi urbani

    Directory of Open Access Journals (Sweden)

    Giuseppe Mazzeo

    2008-08-01

    Full Text Available I grandi eventi sono ritenuti una opportunità per le città in quanto sono uno straordinario catalizzatore di investimenti mirati alla trasformazione della città. L’azione dei grandi eventi non è confinata solo nel periodo di svolgimento dell’evento stesso ma si estende ad un periodo molto più ampio, prima e, soprattutto, dopo il suo termine. Nell’organizzazione delle manifestazioni più recenti le trasformazioni urbane hanno interessato in modo sempre maggiore parti già in precedenza urbanizzate, al punto che l’evento diviene l’occasione per trasformare la città costruita e per modificarne il profilo. Il paper approfondisce l’argomento della classificazione degli eventi e del loro impatto sul sistema urbano sviluppandosi in tre parti. Nella prima si analizzano due tipologie di grandi eventi (le esposizioni internazionali e i giochi olimpici con l’obiettivo di pervenire ad una definizione condivisa. Nella seconda parte si identificano i più importanti fattori ed indicatori per l’analisi di questa specifica categoria di avvenimenti. Infine, nella terza parte, si approfondiscono i fattori connessi all’impatto sul sistema urbano e all’organizzazione della sua mobilità. In particolare, viene approfondito il concetto di “effetto pulsar”, ossia gli effetti moltiplicativi sulla evoluzione urbana dipendenti dalla organizzazione di eventi multipli in parallelo o in sequenza. Uno degli elementi più negativi connessi alla organizzazione di un grande evento è la dispersione nel tempo dei benefici acquisiti grazie ad esso; per evitare ciò è necessario che l’evento sia seguito da politiche strategiche continue in modo da preservare i vantaggi acquisiti.

  3. Indicatori aggregati e settoriali della politica monetaria

    Directory of Open Access Journals (Sweden)

    S. MICOSSI

    2014-03-01

    Full Text Available The recent debate on the management of monetary policy in Italy has paced attention on the problems of the meaning and use of synthetic indicators of monetary conditions. The present work seeks to clarify the logical relationships between the real "indicators" of monetary policy and other monetary magnitudes within the framework of the usual frame of reference instruments-goals intermediate-goals. On the basis of this analysis the authors examine the characteristics and significance of some aggregate monetary indicators currently used in Italy. Particular emphasis is placed on the cognitive limits of the aggregate indicators, which offer the notable advantage of synthetic and timely information, but if "read" in isolation, can sometimes lead to error. They then propose integrating the economic analysis based on aggregate indicators with the systematic use of sectoral indicators derived from the Financial Accounts of the Bank of Italy .  

  4. The environmental performance indicators in the sector of tourist services. The case of study about an international hotel group; Indicatori di performance ambientale nel settore dei servizi turistici. Il caso di studio di una catena alberghiera internazionale

    Energy Technology Data Exchange (ETDEWEB)

    Andriola, L. [ENEA, Div. Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche Casaccia, Rome (Italy); Seminara, M.V.

    2000-07-01

    The environmental performance indicators in the tourism sector represents the necessary element to quantify and to simplify information about the environmental performance of a particular field in order to make the comprehension of the interactions between tourist activities and environment understood by the customers and decision makers. This indicators will have to be quantified in order to contribute to focus and explain improvements in environmental management. One of the most important elements to pursue a Sustainable Development is the definition of a series of the right indicators. Basically performance indicators can be applied in the environmental analyses effected for defining the politics of management of tourist development and, particularly, in the procedures of Environmental Impact Assessment and Strategic Environmental Assessment disciplined by the European Directives 85/337/CEE, 97/11/CEE, from the proposal of Directive on the SEA and from the relative national normative. This tools should allow to esteem environmental conditions and the impacts caused by the tourist activities to find actions to balance the budget between the economic development and the social and environmental issues i a determined territorial context. [Italian] Gli indicatori di performance ambientale applicati al settore del turismo costituiscono l'elemento necessario per quantificare e semplificare le informazioni sulle prestazioni ambientali del settore preso in considerazione, in modo da agevolare, sia da parte dei responsabili delle decisioni, sia da parte del pubblico e dei clienti, la comprensione delle interazioni tra le attivita' turistiche e l'ambiente e le relative criticita'. Tali indicatori dovranno essere quantificati per contribuire ad individuare e a spiegare i miglioramenti ottenuti nel tempo. La definizione di un quadro di indicatori adeguato costituisce pertanto uno degli elementi essenziali per il raggiungimento di uno Sviluppo Sostenibile

  5. The environmental performance indicators in the sector of tourist services. The case of study about an international hotel group; Indicatori di performance ambientale nel settore dei servizi turistici. Il caso di studio di una catena alberghiera internazionale

    Energy Technology Data Exchange (ETDEWEB)

    Andriola, L. [ENEA, Divisione Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche Casaccia, Rome (Italy); Seminara, M.V.

    2001-07-01

    The environmental performance indicators in the tourism sector represents the necessary element to quantify and to simplify information about the environmental performance of a particular field in order to make the comprehension of the interactions between tourist activities and environment understood by the customers and decision makers. This indicators will have to be quantified in order to contribute to focus and explain improvements in environmental management. One of the most important elements to pursue a Sustainable Development is the definition of a series of the right indicators. Basically performance indicators can be applied in the environmental analyses effected for defining the politics of management of tourist development and, particularly, in the procedures of Environmental Impact Assessment and Strategic Environmental Assessment disciplined by the European Directives 85/337/CEE, 97/11/CE, from the proposal of Directive on the SEA and from the relative national normative. This tools should allow to esteem environment conditions and the impacts caused by the tourist activities to find actions to balance the budget between the economic development and the social and environmental issues in a determined territorial context. [Italian] Gli indicatori di performance ambientale applicati settore del turismo costituiscono l'elemento necessario per quantificare e semplificare le informazioni sulle prestazioni ambientali del settore preso in considerazione, in modo da agevolare, sia da parte dei responsabili delle decisioni, sia da parte del pubblico e dei clienti, la comprensione delle interazioni tra le attivita' turistiche e l'ambiente e le relative criticita'. Tali indicatori dovranno essere quantificati per contribuire ad individuare e a spiegare i miglioramenti ottenuti nel tempo. La definizione di un quadro di indicatori adeguato costituisce pertanto uno degli elementi essenziali per il raggiungimento di uno Sviluppo Sostenibile. In

  6. Energy efficiency indicators. Case study, Liguria; Indicatori di efficienza energetica. Il caso Liguria

    Energy Technology Data Exchange (ETDEWEB)

    Ciarallo, M.A. [ENEA, Divisione Promozione degli Usi Efficienti e Diversificazione dell' Energia, Centro Ricerche Casaccia, S. Maria Galeria, RM (Italy)

    2001-07-01

    The report examines the trend in the Liguria Region's energy requirements over the period 1988-1996. The trend was analysed using the regional energy balances and energy efficiency indicators, both in aggregate form and on a single sector basis. The residential sector, in particular, was singled out for an in-depth analysis using publishing and processed data. [Italian] Il presente rapporto esamina l'evoluzione delle caratteristiche energetiche della Regione Liguria attraverso l'analisi degli indicatori di efficienza energetica. Tale analisi e' stata svolta sia a livello aggregato che con riferimento ai singoli settori di attivita'. Particolare attenzione e' stata dedicata al settore residenziale, per il quale e' stato svolto un esame piu' approfondito attraverso un lavoro di raccolta e di elaborazione dati. Il periodo di riferimento va dal 1988 al 1966 dal momento che questo e' l'ultimo anno per il quale sono disponibili i dati economici Istat utilizzati per il calcolo degli indicatori.

  7. Trust Based Routing in Ad Hoc Network

    Science.gov (United States)

    Talati, Mikita V.; Valiveti, Sharada; Kotecha, K.

    Ad Hoc network often termed as an infrastructure-less, self- organized or spontaneous network.The execution and survival of an ad-hoc network is solely dependent upon the cooperative and trusting nature of its nodes. However, this naive dependency on intermediate nodes makes the ad-hoc network vulnerable to passive and active attacks by malicious nodes and cause inflict severe damage. A number of protocols have been developed to secure ad-hoc networks using cryptographic schemes, but all rely on the presence of trust authority. Due to mobility of nodes and limitation of resources in wireless network one interesting research area in MANET is routing. This paper offers various trust models and trust based routing protocols to improve the trustworthiness of the neighborhood.Thus it helps in selecting the most secure and trustworthy route from the available ones for the data transfer.

  8. Targets of industrial development and environmental indicators; Obiettivi di sviluppo industriale e indicatori di prestazioni ambientali. Relazioni di sintesi

    Energy Technology Data Exchange (ETDEWEB)

    Forni, A.; Olivetti, I.; Scipioni, F. [ENEA, Div. Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche Frascati, Frascati, RM (Italy); Orasi, A. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Statistica

    2001-07-01

    georeferenced representations. Conclusive lines regard not only the attitude of enterprises and their approach to environmental themes; the point of view is open to programming choices of regions and other local authorities regarding economic development and environmental protection, both their correlation with a very important national law referring to the funds for industrial development (which gives to regions remarkable role) and the answers of enterprises. [Italian] La ricerca ha inteso monitorare l'uso da parte delle imprese degli indicatori di performance ambientale, in relazione all'accesso a programmi di finanziamento nazionali e/o comunitari, e analizzare il rapporto tra programmazione dello sviluppo industriale e politiche territoriali degli enti locali e dello stato centrale. La ricerca ha focalizzato l'attenzione sulla Legge 488/92 che, tra gli strumenti di incentivazione diretta alle imprese, costituisce la legge di finanziamento piu' rilevante per diversi motivi. Anzitutto per l'impegno finanziario pubblico in quanto e perche' rappresenta la principale legge di finanziamento allo sviluppo dell'imprenditoria e di sostegno all'innovazione nelle aree depresse del Paese (ex aree ob. 1, 2 e 5 b.) Soprattutto, pero', la legge ricorre a degli indicatori ambientali per la valutazione del finanziamento ed ha un rinnovato e piu' ampio ruolo di strumento di attuazione della strategia ambientale del PON sviluppo imprenditoria locale nell'attuale periodo di programmazione dei fondi comunitari, 2000-2006. La delicatezza dell'argomento di studio che coinvolge piu' amministrazioni centrali dello stato e le istituzioni locali con ampie responsabilita', aggiunta alla sua complessita' (economica, sociologica ed ambientale) hanno indotto il gruppo di ricerca ad adottare un metodo di confronto il piu' ampio possibile con elementi scientifici e giuridici/programmatici gia' accettati ed in essere

  9. Targets of industrial development and environmental indicators; Obiettivi di sviluppo industriale e indicatori di prestazioni ambientali. Relazioni di sintesi

    Energy Technology Data Exchange (ETDEWEB)

    Forni, A.; Olivetti, I.; Scipioni, F. [ENEA, Div. Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche Frascati, Frascati, RM (Italy); Orasi, A. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Statistica

    2001-07-01

    georeferenced representations. Conclusive lines regard not only the attitude of enterprises and their approach to environmental themes; the point of view is open to programming choices of regions and other local authorities regarding economic development and environmental protection, both their correlation with a very important national law referring to the funds for industrial development (which gives to regions remarkable role) and the answers of enterprises. [Italian] La ricerca ha inteso monitorare l'uso da parte delle imprese degli indicatori di performance ambientale, in relazione all'accesso a programmi di finanziamento nazionali e/o comunitari, e analizzare il rapporto tra programmazione dello sviluppo industriale e politiche territoriali degli enti locali e dello stato centrale. La ricerca ha focalizzato l'attenzione sulla Legge 488/92 che, tra gli strumenti di incentivazione diretta alle imprese, costituisce la legge di finanziamento piu' rilevante per diversi motivi. Anzitutto per l'impegno finanziario pubblico in quanto e perche' rappresenta la principale legge di finanziamento allo sviluppo dell'imprenditoria e di sostegno all'innovazione nelle aree depresse del Paese (ex aree ob. 1, 2 e 5 b.) Soprattutto, pero', la legge ricorre a degli indicatori ambientali per la valutazione del finanziamento ed ha un rinnovato e piu' ampio ruolo di strumento di attuazione della strategia ambientale del PON sviluppo imprenditoria locale nell'attuale periodo di programmazione dei fondi comunitari, 2000-2006. La delicatezza dell'argomento di studio che coinvolge piu' amministrazioni centrali dello stato e le istituzioni locali con ampie responsabilita', aggiunta alla sua complessita' (economica, sociologica ed ambientale) hanno indotto il gruppo di ricerca ad adottare un metodo di confronto il piu' ampio possibile con elementi scientifici e giuridici/programmatici gia' accettati ed in essere

  10. Gossip Based Ad-Hoc Routing

    OpenAIRE

    Haas, Zygmunt; Halpern, Joseph Y.; Li, Erran L.

    2002-01-01

    Many ad hoc routing protocols are based on some variant of flooding. Despite various optimizations, many routing messages are propagated unnecessarily. We propose a gossiping-based approach, where each node forwards a message with some probability, to reduce the overhead of the routing protocols. Gossiping exhibits bimodal behavior in sufficiently large networks: in some executions, the gossip dies out quickly and hardly any node gets the message; in the remaining executions, a substantial fr...

  11. Life cycle assessment. Specific indicators for Italy in impact evaluation; Life cycle assessment: sviluppo di indicatori specific per l'Italia per la fase di valutazione d'impatto

    Energy Technology Data Exchange (ETDEWEB)

    Masoni, P. [ENEA, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy). Dipt. Energia; Scimia, E. [Bologna Univ., Bologna (Italy)

    1999-07-01

    After a brief recall and a short description of the LCA (life cycle assessment) methodology, the work is focused on the impact assessment step, discussing the state of the art and a critical identification of environmental indicators, of normalization and weighting principles for the different environmental categories specific for Italy. The application methodology to a case study concerning the production of butter by the Consorzio Granterre of Modena (Italy) is also described. [Italian] Il lavoro analizza la fase centrale della metodologia denominata valutazione d'impatto, resentando una rassegna dello stato dell'arte e un'individuazione critica dei possibili indicatori ambientali, di criteri di normalizzazione e di attribuzione di pesi ai diversi temi ambientali specific per l'Italia. Viene descritta l'applicazione ad un caso concreto relativo alla produzione del burro nel consorzio Granterre di Modena.

  12. Enhanced Weight based DSR for Mobile Ad Hoc Networks

    Science.gov (United States)

    Verma, Samant; Jain, Sweta

    2011-12-01

    Routing in ad hoc network is a great problematic, since a good routing protocol must ensure fast and efficient packet forwarding, which isn't evident in ad hoc networks. In literature there exists lot of routing protocols however they don't include all the aspects of ad hoc networks as mobility, device and medium constraints which make these protocols not efficient for some configuration and categories of ad hoc networks. Thus in this paper we propose an improvement of Weight Based DSR in order to include some of the aspects of ad hoc networks as stability, remaining battery power, load and trust factor and proposing a new approach Enhanced Weight Based DSR.

  13. Gossip Based Routing Protocol Design for Ad Hoc Networks

    OpenAIRE

    Toqeer Mahmood; Tabbassam Nawaz; Rehan Ashraf; Syed M. Adnan Shah

    2012-01-01

    A spontaneously mannered decentralized network with no formal infrastructure and limited in temporal and spatial extent where each node communicate with each other over a wireless channel and is willing to forward data for other nodes is called as Wireless Ad Hoc network. In this research study, we proposed a routing strategy based on gossip based routing approach that follows the proactive routing with some treatment for wireless Ad Hoc network. The analytical verification of our proposed id...

  14. Link Perdurability Based Routing for Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Sun Xuebin; Zhou Zheng

    2003-01-01

    Ad Hoc networks are prone to link failures due to mobility. In this letter, a link perdurability based routing scheme is proposed to try dealing with this problem. This scheme uses signal strength measurements to estimate the route life time and hence chooses a stable route, and is implemented in two typical ad hoc routing protocols to evaluate its performance. The simulation results have shown that this scheme can improve these protocols' packet delivery ratio in cases where there are frequent link failures.

  15. Ad-hoc Network Based on ARM-Linux%基于ARM-Linux的Ad-hoc组网

    Institute of Scientific and Technical Information of China (English)

    王晓华; 贾继洋

    2014-01-01

    Aiming to solve the problem of the contemporary communication system in the absence of any network, a new scheme of the Ad-hoc network based on ARM-Linux system is designed. Firstly, this paper introduces the transportation of the Linux2.6.36 and the driver of RT3070 on ARM11 platform. Then based on socket programming in TCP/IP, program designing of communication and tests are conducted on the ARM-Linux platform. Results have proved that the Ad-hoc network can use the least resources and costs to achieve reliable high rate communication. It is significant for practical application.%针对传统通信系统不能满足在无任何网络情况下的通信需求现状,设计并实现了一种由 ARM-Linux 系统及其外围部件组成的无线自组网(Ad-hoc)的通信方案.在 ARM11平台上完成了 Linux2.6.36操作系统和RT3070无线通信模块的驱动程序移植.利用基于TCP/IP协议的socket编程,编写测试程序,进行节点间无线通信传输实验.实验结果表明:本文搭建的Ad-hoc网络,可以用最少的资源和成本,实现节点间可靠的无线高速率通信,具有现实应用意义.

  16. Gossip Based Routing Protocol Design for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Toqeer Mahmood

    2012-01-01

    Full Text Available A spontaneously mannered decentralized network with no formal infrastructure and limited in temporal and spatial extent where each node communicate with each other over a wireless channel and is willing to forward data for other nodes is called as Wireless Ad Hoc network. In this research study, we proposed a routing strategy based on gossip based routing approach that follows the proactive routing with some treatment for wireless Ad Hoc network. The analytical verification of our proposed idea shows that it is a better approach based on gossip routing.

  17. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks

    Science.gov (United States)

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV. PMID:27258013

  18. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks.

    Directory of Open Access Journals (Sweden)

    Abdulaziz Al-Nahari

    Full Text Available Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV, which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV.

  19. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks.

    Science.gov (United States)

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV.

  20. Auto correct method of AD converters precision based on ethernet

    Directory of Open Access Journals (Sweden)

    NI Jifeng

    2013-10-01

    Full Text Available Ideal AD conversion should be a straight zero-crossing line in the Cartesian coordinate axis system. While in practical engineering, the signal processing circuit, chip performance and other factors have an impact on the accuracy of conversion. Therefore a linear fitting method is adopted to improve the conversion accuracy. An automatic modification of AD conversion based on Ethernet is presented by using software and hardware. Just by tapping the mouse, all the AD converter channel linearity correction can be automatically completed, and the error, SNR and ENOB (effective number of bits are calculated. Then the coefficients of linear modification are loaded into the onboard AD converter card's EEPROM. Compared with traditional methods, this method is more convenient, accurate and efficient,and has a broad application prospects.

  1. Multiagent Based Information Dissemination in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    S.S. Manvi

    2009-01-01

    Full Text Available Vehicular Ad hoc Networks (VANETs are a compelling application of ad hoc networks, because of the potential to access specific context information (e.g. traffic conditions, service updates, route planning and deliver multimedia services (Voice over IP, in-car entertainment, instant messaging, etc.. This paper proposes an agent based information dissemination model for VANETs. A two-tier agent architecture is employed comprising of the following: 1 'lightweight', network-facing, mobile agents; 2 'heavyweight', application-facing, norm-aware agents. The limitations of VANETs lead us to consider a hybrid wireless network architecture that includes Wireless LAN/Cellular and ad hoc networking for analyzing the proposed model. The proposed model provides flexibility, adaptability and maintainability for traffic information dissemination in VANETs as well as supports robust and agile network management. The proposed model has been simulated in various network scenarios to evaluate the effectiveness of the approach.

  2. Authentication Based on Multilayer Clustering in Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Suh Heyi-Sook

    2005-01-01

    Full Text Available In this paper, we describe a secure cluster-routing protocol based on a multilayer scheme in ad hoc networks. This work provides scalable, threshold authentication scheme in ad hoc networks. We present detailed security threats against ad hoc routing protocols, specifically examining cluster-based routing. Our proposed protocol, called "authentication based on multilayer clustering for ad hoc networks" (AMCAN, designs an end-to-end authentication protocol that relies on mutual trust between nodes in other clusters. The AMCAN strategy takes advantage of a multilayer architecture that is designed for an authentication protocol in a cluster head (CH using a new concept of control cluster head (CCH scheme. We propose an authentication protocol that uses certificates containing an asymmetric key and a multilayer architecture so that the CCH is achieved using the threshold scheme, thereby reducing the computational overhead and successfully defeating all identified attacks. We also use a more extensive area, such as a CCH, using an identification protocol to build a highly secure, highly available authentication service, which forms the core of our security framework.

  3. Effect of Modifying Prosthetic Socket Base Materials by Adding Nanodiamonds

    Directory of Open Access Journals (Sweden)

    Lifang Ma

    2015-01-01

    Full Text Available The curing process of prosthetic socket base materials requires attention owing to a series of associated problems that are yet to be addressed and solved. However, to date, few relevant studies have been reported. In this paper, nanodiamonds modified with a silane coupling agent were dispersed into a prosthetic socket base material, and the performance of the modified base materials was investigated. Adding a predetermined amount of nanodiamonds to the prosthetic socket base material increased the glass transition temperature, improved the mechanical properties of the cured base material, and reduced the influence of the volatile gas formed during the curing process on the environment. With increasing nanodiamond contents, the glass transition temperature increased and the mechanical properties improved slightly. Owing to the high thermal conductivity of the nanodiamonds, the localized heat, as a result of the curing process, could be dissipated and released. Thus, adding nanodiamonds led to a more uniform temperature field forming in the curing system. This improved the curing process and reduced the formation of volatile monomers, thereby decreasing the adverse impact of the generated volatile gases on the environment. All of these provide a potential strategy for modifying prosthetic socket base materials.

  4. Cost management based security framework in mobile ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Security issues are always difficult to deal with in mobile ad hoc networks. People seldom studied the costs of those security schemes respectively and for some security methods designed and adopted beforehand, their effects are often investigated one by one. In fact, when facing certain attacks, different methods would respond individually and result in waste of resources.Making use of the cost management idea, we analyze the costs of security measures in mobile ad hoc networks and introduce a security framework based on security mechanisms cost management. Under the framework, the network system's own tasks can be finished in time and the whole network's security costs can be decreased. We discuss the process of security costs computation at each mobile node and in certain nodes groups. To show how to use the proposed security framework in certain applications, we give examples of DoS attacks and costs computation of defense methods. The results showed that more secure environment can be achieved based on the security framework in mobile ad hoc networks.

  5. Reformative multicast routing protocol based on Ad Hoc

    Institute of Scientific and Technical Information of China (English)

    杨喜旺; 王华; 焦国太

    2008-01-01

    Mobile Ad Hoc networks has been widely applied to military field, emergency management, public service and so on. Because it is uncertain on network and communication, a great deal of energy will be consumed with nodes increasing and creating routing each other. The reformative on-demand multicast routing protocol was putted forward by researching the energy consuming of multicast routing protocol in Ad Hoc. It will decrease consumption in a big multicast flooding through studying the relaying group net structure based on map or wormhole. The energy consumption is reduced 30% by creating the two kinds of routing principles: minimization of energy consumption and minimization of maximum nodes energy consumption. The simulation result indicates that the reformative RODMRP is effective to reduce the energy consuming while routing protocol built.

  6. HASM-AD Algorithm Based on the Sequential Least Squares

    Institute of Scientific and Technical Information of China (English)

    WANG Shihai; YUE Tianxiang

    2010-01-01

    The HASM (high accuracy surface modeling) technique is based on the fundamental theory of surfaces, which has been proved to improve the interpolation accuracy in surface fitting. However, the integral iterative solution in previous studies resulted in high temporal complexity in computation and huge memory usage so that it became difficult to put the technique into application,especially for large-scale datasets. In the study, an innovative model (HASM-AD) is developed according to the sequential least squares on the basis of data adjustment theory. Sequential division is adopted in the technique, so that linear equations can be divided into groups to be processed in sequence with the temporal complexity reduced greatly in computation. The experiment indicates that the HASM-AD technique surpasses the traditional spatial interpolation methods in accuracy. Also, the cross-validation result proves the same conclusion for the spatial interpolation of soil PH property with the data sampled in Jiangxi province. Moreover, it is demonstrated in the study that the HASM-AD technique significantly reduces the computational complexity and lessens memory usage in computation.

  7. Escape probability based routing for ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    Zhang Xuanping; Qin Zheng; Li Xin

    2006-01-01

    Routes in an ad hoc network may fail frequently because of node mobility. Stability therefore can be an important element in the design of routing protocols. The node escape probability is introduced to estimate the lifetime and stability of link between neighboring nodes and the escape probability based routing (EPBR) scheme to discover stable routes is proposed. Simulation results show that the EPBR can discover stable routes to reduce the number of route rediscovery, and is applicable for the situation that has highly dynamic network topology with broad area of communication.

  8. Ad hoc Routing Protocol Based on NS%基于NS的Ad hoc路由协议研究

    Institute of Scientific and Technical Information of China (English)

    谢建武

    2012-01-01

    Based on the analysis of the Ad Hoc wireless network basic characteristics,and on the basis of Ad Hoc network reviewed the research status of main routing protocol,and discussed the Ad Hoc wireless network routing protocols of the development trends and challenges,the Ad Hoc of several typical network routing protocols the characteristics of the classification analysis and comparison.And focuses on analyzing the AODV,DSDV,DSR three agreement and the characteristics of the routing mechanism,and use the NS2 simulation software of the simulation,and again from the simulation results of data analysis,draw diagrams are compared.%在分析Ad Hoc无线网络基本特性的基础上,综合评述Ad Hoc网络路由协议主要的研究现状,讨论Ad Hoc无线网络路由协议的发展趋势和挑战。对几种典型的Ad Hoc网络路由协议的特点进行分类分析和比较,着重分析AODV,DSDV,DSR等3种协议的特点及路由机制,并使用NS2仿真软件对其仿真,再从仿真结果中分析数据,绘出图表进行比较。

  9. Methodological procedures and analytical instruments to evaluate an indicators integrated archive for urban management; Guida metodologica per la costruzione di un archivio integrato di indicatori urbani

    Energy Technology Data Exchange (ETDEWEB)

    Del Ciello, R.; Napoleoni, S. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1998-07-01

    This guide provides the results of a research developed at ENEA (National Agency for new Technology, Energy and the Environment) Casaccia center (Rome, Italy) aimed to define methodological procedures and analytical instruments needed to carry out an indicators integrated archive for urban management. The guide also defines the scheme of a negotiation process aimed to reach and exchange data and information among governmental and local administrations, non-governmental organizations and scientific bodies. [Italian] Il lavoro presenta una sintesi dei risultati di una ricerca condotta presso il C.R. Casaccia dell'ENEA, relativia alla definizione di procedure metodologiche e strumenti di analisi ed elaborazione per realizzare un archivio integrato di indicatori per la gestione dei sistemi urbani. La guida, rivolta ai responsabili delle politiche urbane, deifinisce uno schema dei processi di condivisione degli indicatori urbani attraverso l'organizzazione di opportuni tavoli negoziali, costituiti da rappresentanti delle amministrazioni locali, dell'amministrazione centrale, delle categorie produttive e sociali e delle strutture tecniche operanti sul territorio.

  10. INDICATORI DE PERFORMANŢĂ ÎN CONTEXTUL REGLEMENTĂRILOR CONTABILE INTERNAŢIONALE

    Directory of Open Access Journals (Sweden)

    Neculai Tabara

    2007-05-01

    Full Text Available Performance Accounting and Analysis provides metrics definitions, compliance tracking, costaccounting by task order, functional area for full-cost accounting with reporting tools for management, alongwith a complete array of data-extraction methods. The comprehensive income is a project which addressesbroadly the issues related to the display and presentation in the financial statements of all recognized changes inassets and liabilities from transactions or other events except those related to transactions with owners asowners (sometimes called comprehensive income. The other two measures of financial performance that arebeing applied increasingly in investor-owned and not-for-profit healthcare organizations are market valueadded (MVA and economic value added (EVA. Unlike traditional profitability measures, both MVA and EVAmeasures take into account the cost of equity capital. MVA is most appropriate for investor-owned healthcareorganizations and EVA is the best measure for not-for-profit organizations.

  11. Location Based Opportunistic Routing Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jubin Sebastian E

    2012-01-01

    Full Text Available : Most existing ad hoc routing protocols are susceptible to node mobility, especially for large-scale networks. This paper proposes a Location Based Opportunistic Routing Protocol (LOR to addresses the problem of delivering data packets for highly dynamic mobile ad hoc networks in a reliable and timely manner.This protocol takes advantage of the stateless property of geographic routing and the broadcast nature of wireless medium. When a data packet is sent out, some of the neighbor nodes that have overheard the transmission will serve as forwarding candidates, and take turn to forward the packet if it is not relayed by the specific best forwarder within a certain period of time. By utilizing such in-the-air backup, communication is maintained without being interrupted. The additional latency incurred by local route recovery is greatly reduced and the duplicate relaying caused by packet reroute is also decreased. Simulation results on NS2 verified the effectiveness of the proposed protocol with improvement in throughput by 28%.

  12. Station-based Surface Data Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Q. [DOE ARM Climate Research Facility, Washington, DC (United States); Xie, S. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    This report describes the Atmospheric Radiation Measurement (ARM) Best Estimate (ARMBE) station-based surface data (ARMBESTNS) value-added product. It is a twin data product of the ARMBE 2-Dimensional gridded (ARMBE2DGRID) data set. Unlike the ARMBE2DGRID data set, ARMBESTNS data are reported at the original site locations and show the original information (except for the interpolation over time). Therefore, the users have the flexibility to process the data with the approach more suitable for their applications. This document provides information about the input data, quality control (QC) method, and output format of this data set. As much of the information is identical to that of the ARMBE2DGRID data, this document will emphasize more on the different aspects of these two data sets.

  13. Contributo alla definizione delle fasi iniziali della Media età del Bronzo in Italia centro-settentrionale: le impugnature con appendice ad ascia

    Directory of Open Access Journals (Sweden)

    Maurizio Cattani

    2011-12-01

    Full Text Available Il contributo prende in esame le impugnature con appendice ad ascia, considerate tra gli indicatori archeologici più significativi del processo di espansione demografica e culturale avvenuta agli inizi della media età del Bronzo in Italia settentrionale. La tipologia e l’analisi di distribuzione delle presenze permettono di rivalutare i meccanismi della produzione ceramica e dei processi di interazione culturale.

  14. On classical Yang-Baxter based deformations of the AdS_5 x S^5 superstring

    CERN Document Server

    van Tongeren, Stijn J

    2015-01-01

    Interesting deformations of AdS_5 x S^5 such as the gravity dual of noncommutative SYM and Sch\\"odinger spacetimes have recently been shown to be integrable. We clarify questions regarding the reality and integrability properties of the associated construction based on R matrices that solve the classical Yang-Baxter equation, and present an overview of manifestly real R matrices associated to the various deformations. We also discuss when these R matrices should correspond to TsT transformations, which not all do, and briefly analyze the symmetries preserved by these deformations, for example finding Schr\\"odinger superalgebras that were previously obtained as subalgebras of psu(2,2|4). Our results contain a (singular) generalization of an apparently non-TsT deformation of AdS_5 x S^5, whose status as a string background is an interesting open question.

  15. Environmental indicators update corporate communication; Gli indicatori ambientali aggiornano la comunicazione d'impresa

    Energy Technology Data Exchange (ETDEWEB)

    Luciani, R.; Andriola, L. [ENEA, Centro Ricerche Casaccia, RM (Italy). Dipt. Ambiente; Borghini, S. [Ente Nazionale Idrocarburi, Milan (Italy). Fondazione Enrico Mattei

    2000-04-01

    The communication of environmental aspects is becoming a strategic factor for companies, which are subject to increasing pressure due to the need to strengthen their dialogue with the local community and interest groups: environmentalist groups, local communities and local and national authorities. Not to mention employees, shareholders, banks, insurance companies, clients and suppliers. By now one demands reliable information on the environment, in addition to economic and equity figures, both on the occasion of acquisitions and of funding; such data may in some cases also influence insurance premiums. In fact, guarantees on environmental performance is requested more and more frequently, as a violation of environmental regulations may entail heavy liabilities and influence the overall value of a company profoundly. Moreover, green investment funds which only invest provided the companies desirous of funding may offer clear guarantees on their environmental quality are beginning to operate, also on national level. [Italian] La comunicazione ambientale sta diventando un fattore strategico per le aziende sempre piu' pressate dalla necessita' di rafforzare il dialogo con il territorio e con i portatori di interesse: i gruppi ambientalisti, le comunita' locali, le autorita' locali e nazionali. Ma anche con i dipendenti, gli azionisti, le banche, gli assicuratori, i clienti e i fornitori. Ormai informazioni ambientali attendibili vengono richieste, cosi' come i dati economici e patrimoniali, sia in sede di acquisizione di societa' che di finanziamento e possono, in alcuni casi, anche influenzare i premi assicurativi. Sempre piu' spesso vengono infatti richieste garanzie sul piano ambientale in quanto una violazione della normativa ambientale puo' comportare forti passivita' e incidere pesanetemente sul valore complessivo dell'azienda. Cominciano inoltre ad operare, anche a livello nazionale, fondi di investimento verdi

  16. Reliability analysis of cluster-based ad-hoc networks

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Jason L. [Quality Engineering and System Assurance, Armament Research Development Engineering Center, Picatinny Arsenal, NJ (United States); Ramirez-Marquez, Jose Emmanuel [School of Systems and Enterprises, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 (United States)], E-mail: Jose.Ramirez-Marquez@stevens.edu

    2008-10-15

    The mobile ad-hoc wireless network (MAWN) is a new and emerging network scheme that is being employed in a variety of applications. The MAWN varies from traditional networks because it is a self-forming and dynamic network. The MAWN is free of infrastructure and, as such, only the mobile nodes comprise the network. Pairs of nodes communicate either directly or through other nodes. To do so, each node acts, in turn, as a source, destination, and relay of messages. The virtue of a MAWN is the flexibility this provides; however, the challenge for reliability analyses is also brought about by this unique feature. The variability and volatility of the MAWN configuration makes typical reliability methods (e.g. reliability block diagram) inappropriate because no single structure or configuration represents all manifestations of a MAWN. For this reason, new methods are being developed to analyze the reliability of this new networking technology. New published methods adapt to this feature by treating the configuration probabilistically or by inclusion of embedded mobility models. This paper joins both methods together and expands upon these works by modifying the problem formulation to address the reliability analysis of a cluster-based MAWN. The cluster-based MAWN is deployed in applications with constraints on networking resources such as bandwidth and energy. This paper presents the problem's formulation, a discussion of applicable reliability metrics for the MAWN, and illustration of a Monte Carlo simulation method through the analysis of several example networks.

  17. Random Time Identity Based Firewall In Mobile Ad hoc Networks

    Science.gov (United States)

    Suman, Patel, R. B.; Singh, Parvinder

    2010-11-01

    A mobile ad hoc network (MANET) is a self-organizing network of mobile routers and associated hosts connected by wireless links. MANETs are highly flexible and adaptable but at the same time are highly prone to security risks due to the open medium, dynamically changing network topology, cooperative algorithms, and lack of centralized control. Firewall is an effective means of protecting a local network from network-based security threats and forms a key component in MANET security architecture. This paper presents a review of firewall implementation techniques in MANETs and their relative merits and demerits. A new approach is proposed to select MANET nodes at random for firewall implementation. This approach randomly select a new node as firewall after fixed time and based on critical value of certain parameters like power backup. This approach effectively balances power and resource utilization of entire MANET because responsibility of implementing firewall is equally shared among all the nodes. At the same time it ensures improved security for MANETs from outside attacks as intruder will not be able to find out the entry point in MANET due to the random selection of nodes for firewall implementation.

  18. Metric-Based Cooperative Routing in Multihop Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Xin He

    2012-01-01

    Full Text Available Cooperative communication fully leverages the broadcast nature of wireless channels and exploits time/spatial diversity in a distributed manner, thereby achieving significant improvements in system capacity and transmission reliability. Cooperative diversity has been well studied from the physical layer perspective. Thereafter, cooperative MAC design has also drawn much attention recently. However, very little work has addressed cooperation at the routing layer. In this paper, we propose a simple yet efficient scheme for cooperative routing by using cooperative metrics including packet delivery ratio, throughput, and energy consumption efficiency. To make a routing decision based on our scheme, a node needs to first determine whether cooperation on each link is necessary or not, and if necessary, select the optimal cooperative scheme as well as the optimal relay. To do so, we calculate and compare cooperative routing metric values for each potential relay for each different cooperative MAC scheme (C-ARQ and CoopMAC in this study, and further choose the best value and compare it with the noncooperative link metric. Using the final optimal metric value instead of the traditional metric value at the routing layer, new optimal paths are set up in multihop ad hoc networks, by taking into account the cooperative benefits from the MAC layer. The network performance of the cooperative routing solution is demonstrated using a simple network topology.

  19. Cognitive Radio-Based Vehicular Ad Hoc and Sensor Networks

    National Research Council Canada - National Science Library

    Jalil Piran, Mohammad; Cho, Yongwoo; Yun, Jihyeok; Ali, Amjad; Suh, Doug Young

    2014-01-01

    ... the spectrum scarcity issue. We have already proposed vehicular ad hoc and sensor networks (VASNET) as a new networking paradigm for vehicular communication by utilizing wireless sensor nodes in two mobile and stationary modes...

  20. Ad intrusiveness of location-based advertising: A virtual reconstruction

    NARCIS (Netherlands)

    Huhn, A.E.; Ketelaar, P.E.; Khan, V.J.; Lucero, A.; Bouwknegt, H.

    2012-01-01

    An important problem for advertisers is the general tendency to avoid advertising (Li et al., 2002; McCoy et al., 2008; Zanot, 1984). Ads typically get the 'blame' that they do not meet the goals and desires of consumers, thus the commercial message is perceived as disturbing and therefore avoided (

  1. Value added based on educational positions in Dutch secondary education

    NARCIS (Netherlands)

    Timmermans, Anneke C.; Bosker, Roel J.; de Wolf, Inge F.; Doolaard, Simone; van der Werf, Margaretha P.C.

    2014-01-01

    Estimating added value as an indicator of school effectiveness in the context of educational accountability often occurs using test or examination scores of students. This study investigates the possibilities of using scores for educational positions as an alternative indicator. A number of

  2. Adding Quality of Service Extensions to the Enhanced Associativity Based Routing Protocol for Mobile Ad Hoc Networks (MANET

    Directory of Open Access Journals (Sweden)

    A. M. Murad

    2007-01-01

    Full Text Available This paper described how to discover routes that can satisfy QoS service requirements by using extensions to the Enhanced Associativity Bases Routing Protocol (EABR. These extensions were added to the messages used during route discovery. These extensions specify the service requirements, which must be met by nodes re-broadcasting a route request or returning a route reply for a destination. The performance analysis of EABR with QoS support showed that more overhead was incurred when the intermediate node discover that it cannot support the level of the QoS requested.

  3. Gli indicatori bibliometrici: riflessioni sparse per un uso attento e consapevole Bibliometric indicators: spread reflections for a focusing and conscious use

    Directory of Open Access Journals (Sweden)

    Tessa Piazzini

    2010-06-01

    Full Text Available The usage of bibliometric indicators is widespread in the scientific and academic world, and has become a standard in order to assign research funds and to assess the results of those investments. The aim of this article is to offer, without any claims for comprehensiveness some reflections and advices for using these tools in a more conscious way, highlighting their limits and peculiarities. Apart from Impact Factor, many tools related to Open Access have been developed recently. The most valuable options are given by Scimago, a free tool by the CSIC (Consejo Superior de Investigaciones Científicas, and Eigenfactor, research project of the the University of Washington. The H-Index (or Hirsch Index, developed in 2005 by professor Jorge E. Hirsch at the university of California, offers a valid option to the previous bibliometric analysis tools: the H-Index attempts to reduce some excesses of the Citation Index, making compliant very prolific but low quoted authors, with less prolific and high quoted ones.Nel mondo scientifico e accademico l'uso di indicatori bibliometrici è ormai largamente diffuso ed è diventato un  parametro di giudizio per assegnare fondi di ricerca e valutare i risultati degli investimenti. Lo scopo di questo articolo è quello di fornire, senza alcuna pretesa di completezza, spunti di riflessione e consigli pratici per un utilizzo consapevole degli indicatori bibliometrici più consolidati, segnalandone i limiti e le peculiarità. Oltre al più noto e discusso indicatore bibliometrico, l'Impact factor, sono stati sviluppati negli ultimi anni alcuni sistemi alternativi legati all'open acess. Le più valide alternative sono rappresentate da Scimago, strumento gratuitamente consultabile on-line nato da un gruppo di ricerca del Consejo Superior de Investigaciones Científicas (CSIC in collaborazione con alcune università spagnole e Eigenfactor, progetto di ricerca accademica non-commerciale sponsorizzato dal Bergstrom lab

  4. AD5933-based spectrometer for electrical bioimpedance applications

    Science.gov (United States)

    Ferreira, J.; Seoane, F.; Ansede, A.; Bragos, R.

    2010-04-01

    To build an Electrical Bioimpedance (EBI) spectrometer using the Impedance Measurement System-On-Chip AD5933 together with a 4-Electrode Analog Front End (4E-AFE) has been proven practicable. Such small measurement devices can make possible several new applications of EBI technology, especially when combined with functional textiles, which can enable wearable applications for personal health and home monitoring. After the implementation and functional validation of the 4E-AFE-enabled spectrometer, the next natural step is to validate for which EBI applications the 4E-AFE-enabled system is suitable. To test the applicability of this novel spectrometer on several EBI applications, 2R1C equivalent models have been experimentally obtained and impedance spectroscopy measurements have been performed with the system under study and with the SFB7 EBI spectrometer manufactured by ImpediMed. The 2R1C circuit parameters have been estimated with the BioImp software from the spectra obtained with both EBI spectrometers and the estimated values have been compared with the original values used in each circuit model implementation. The obtained results indicated that the 4E-AFE-enabled system cannot beat the performance of the SFB7 in accuracy but it performs better in preciseness. In any case the overall performance indicates that the 4E-AFE-enabled system can perform spectroscopy measurements in the frequency range from 5 to 100 kHz.

  5. Green Net Value Added as a Sustainability Metric Based on ...

    Science.gov (United States)

    Sustainability measurement in economics involves evaluation of environmental and economic impact in an integrated manner. In this study, system level economic data are combined with environmental impact from a life cycle assessment (LCA) of a common product. We are exploring a costing approach that captures traditional costs but also incorporates externality costs to provide a convenient, easily interpretable metric. Green Net Value Added (GNVA) is a type of full cost accounting that incorporates total revenue, the cost of materials and services, depreciation, and environmental externalities. Two, but not all, of the potential environmental impacts calculated by the standard LCIA method (TRACI) could be converted to externality cost values. We compute externality costs disaggregated by upstream sectors, full cost, and GNVA to evaluate the relative sustainability of Bounty® paper towels manufactured at two production facilities. We found that the longer running, more established line had a higher GNVA than the newer line. The dominant factors contributing to externality costs are calculated to come from the stationary sources in the supply chain: electricity generation (27-35%), refineries (20-21%), pulp and paper making (15-23%). Health related externalities from Particulate Matter (PM2.5) and Carbon Dioxide equivalent (CO2e) emissions appear largely driven by electricity usage and emissions by the facilities, followed by pulp processing and transport. Supply

  6. Adding trend data to Depletion-Based Stock Reduction Analysis

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Bayesian model of Depletion-Based Stock Reduction Analysis (DB-SRA), informed by a time series of abundance indexes, was developed, using the Sampling Importance...

  7. Trust recovery model of Ad Hoc network based on identity authentication scheme

    Science.gov (United States)

    Liu, Jie; Huan, Shuiyuan

    2017-05-01

    Mobile Ad Hoc network trust model is widely used to solve mobile Ad Hoc network security issues. Aiming at the problem of reducing the network availability caused by the processing of malicious nodes and selfish nodes in mobile Ad Hoc network routing based on trust model, an authentication mechanism based on identity authentication mobile Ad Hoc network is proposed, which uses identity authentication to identify malicious nodes, And trust the recovery of selfish nodes in order to achieve the purpose of reducing network congestion and improving network quality. The simulation results show that the implementation of the mechanism can effectively improve the network availability and security.

  8. Cluster-based Intrusion Detection in Wireless Ad-Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Di Wu; Zhisheng Liu; Yongxin Feng; Guangxing Wang

    2004-01-01

    There are inherent vulnerabilities that are not easily preventable in the mobile Ad-Hoc networks.To build a highly secure wireless Ad-Hoc network,intrusion detection and response techniques need to be deployed;The intrusion detection and cluster-based Ad-Hoc networks has been introduced,then,an architecture for better intrusion detection based on cluster using Data Mining in wireless Ad-Hoc networks has been shown. A statistical anomaly detection approach has been used.The anomaly detection and trace analysis have been done locally in each node and possibly through cooperation with clusterhead detection in the network.

  9. Adding Social Elements to Game-Based Learning

    Directory of Open Access Journals (Sweden)

    Chien-Hung Lai

    2014-05-01

    Full Text Available Game-based learning is to present the instruction by games in learning, with the main purpose of triggering learners’ motives instead of instructing the courses. Thus, increasing learning motive by game-based learning becomes a common instructional strategy to enhance learning achievement. However, it is not easy to design interesting games combined with courses. In 2011, Echeverria proposed a design to combine characteristics of games with elements of courses by matching the virtual scenarios in games with proper courses. However, in the past game-based learning, students were gathered in regular places for several times of game-based learning. Students’ learning was limited by time and space. Therefore, for students’ game-based learning at any time and in any places, based on theories of design elements of online community game Aki Järvinen, this study treats Facebook as the platform of games. The development by online community game is easier, faster and cheaper than traditional video games. In 2006, Facebook allowed API program of the third party. Therefore, by Facebook, this study provides the platform for students to learn in social lives to explore students’ activities in online community games. Questionnaire survey is conducted to find out if the design of non-single user game is attractive for students to participate in game-based learning. In order to make sure that the questionnaires can be the criteria to investigate students’ intention to play games, by statistical program of social science; this study validates reliability and validity of items of questionnaire to effectively control the effect of online community games on students’ learning intention.

  10. Adding dispositions to create pedagogy-based Learning Analytics

    NARCIS (Netherlands)

    Tempelaar, Dirk; Rienties, Bart; Nguyen, Quan

    This empirical study aims to demonstrate how Dispositional Learning Analytics (DLA) can provide a strong connection between Learning Analytics (LA) and pedagogy. Where LA based models typically do well in predicting course performance or student drop-out, they lack actionable data in order to easily

  11. Adding dispositions to create pedagogy-based Learning Analytics

    NARCIS (Netherlands)

    Tempelaar, Dirk; Rienties, Bart; Nguyen, Quan

    2017-01-01

    This empirical study aims to demonstrate how Dispositional Learning Analytics (DLA) can provide a strong connection between Learning Analytics (LA) and pedagogy. Where LA based models typically do well in predicting course performance or student drop-out, they lack actionable data in order to easily

  12. Coupled interference based rate adaptation in ad hoc networks

    CSIR Research Space (South Africa)

    Awuor, F

    2011-09-01

    Full Text Available on Karush-Kuhn-Tucker (KKT) conditions. The users determine data rates based on their local observations (i.e. coupled interference). Both pricing and limited message passing mechanisms are employed in the NUM wherein pricing restrict users from self...

  13. Rate adaptation in ad hoc networks based on pricing

    CSIR Research Space (South Africa)

    Awuor, F

    2011-09-01

    Full Text Available to transmit at high power leading to abnormal interference in the network hence degrades network performance (i.e. low data rates, loss of connectivity among others). In this paper, the authors propose rate adaptation based on pricing (RAP) algorithm...

  14. Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit

    OpenAIRE

    Chabowski Konrad; Piasecki Tomasz; Dzierka Andrzej; Nitsch Karol

    2015-01-01

    As it contains elements of complete digital impedance meter, the AD5933 integrated circuit is an interesting solution for impedance measurements. However, its use for measurements in a wide range of impedances and frequencies requires an additional digital and analogue circuitry. This paper presents the design and performance of a simple impedance meter based on the AD5933 IC. Apart from the AD5933 IC it consists of a clock generator with a programmable prescaler, a novel DC offset canceller ...

  15. Condensation-Based Routing in Mobile Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Francesco Palmieri

    2012-01-01

    Full Text Available The provision of efficient broadcast containment schemes that can dynamically cope with frequent topology changes and limited shared channel bandwidth, is one of the most challenging research topics in MANETs, and is crucial to the basic operations of networks serving fully mobile devices within areas having no fixed communication infrastructure. This problem particularly impacts the design of dynamic routing protocol that can efficiently establish routes to deliver data packets among mobile nodes with minimum communication overhead, and at the same time, ensure high throughput and low end-to-end delay. Accordingly, this work exploits and analyzes an adaptive probabilistic broadcast containment technique based on a particular condensation phenomenon borrowed from Quantum Mechanics and transposed in self-organizing random networks, that has the potential to effectively drive the on-demand route discovery process. Simulation-based performance analysis has shown that the proposed technique can introduce significant benefits on the general performance of broadcast-based reactive routing protocols in MANETs.

  16. Clustering in mobile ad hoc network based on neural network

    Institute of Scientific and Technical Information of China (English)

    CHEN Ai-bin; CAI Zi-xing; HU De-wen

    2006-01-01

    An on-demand distributed clustering algorithm based on neural network was proposed. The system parameters and the combined weight for each node were computed, and cluster-heads were chosen using the weighted clustering algorithm, then a training set was created and a neural network was trained. In this algorithm, several system parameters were taken into account, such as the ideal node-degree, the transmission power, the mobility and the battery power of the nodes. The algorithm can be used directly to test whether a node is a cluster-head or not. Moreover, the clusters recreation can be speeded up.

  17. Value-Added Dairy Products from Grass-Based Dairy Farms: A Case Study in Vermont

    Science.gov (United States)

    Wang, Qingbin; Parsons, Robert; Colby, Jennifer; Castle, Jeffrey

    2016-01-01

    On-farm processing of value-added dairy products can be a way for small dairy farms to diversify production and increase revenue. This article examines characteristics of three groups of Vermont farmers who have grass-based dairy farms--those producing value-added dairy products, those interested in such products, and those not interested in such…

  18. Value-Added Dairy Products from Grass-Based Dairy Farms: A Case Study in Vermont

    Science.gov (United States)

    Wang, Qingbin; Parsons, Robert; Colby, Jennifer; Castle, Jeffrey

    2016-01-01

    On-farm processing of value-added dairy products can be a way for small dairy farms to diversify production and increase revenue. This article examines characteristics of three groups of Vermont farmers who have grass-based dairy farms--those producing value-added dairy products, those interested in such products, and those not interested in such…

  19. Battery Performance Modelling ad Simulation: a Neural Network Based Approach

    Science.gov (United States)

    Ottavianelli, Giuseppe; Donati, Alessandro

    2002-01-01

    This project has developed on the background of ongoing researches within the Control Technology Unit (TOS-OSC) of the Special Projects Division at the European Space Operations Centre (ESOC) of the European Space Agency. The purpose of this research is to develop and validate an Artificial Neural Network tool (ANN) able to model, simulate and predict the Cluster II battery system's performance degradation. (Cluster II mission is made of four spacecraft flying in tetrahedral formation and aimed to observe and study the interaction between sun and earth by passing in and out of our planet's magnetic field). This prototype tool, named BAPER and developed with a commercial neural network toolbox, could be used to support short and medium term mission planning in order to improve and maximise the batteries lifetime, determining which are the future best charge/discharge cycles for the batteries given their present states, in view of a Cluster II mission extension. This study focuses on the five Silver-Cadmium batteries onboard of Tango, the fourth Cluster II satellite, but time restrains have allowed so far to perform an assessment only on the first battery. In their most basic form, ANNs are hyper-dimensional curve fits for non-linear data. With their remarkable ability to derive meaning from complicated or imprecise history data, ANN can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computer techniques. ANNs learn by example, and this is why they can be described as an inductive, or data-based models for the simulation of input/target mappings. A trained ANN can be thought of as an "expert" in the category of information it has been given to analyse, and this expert can then be used, as in this project, to provide projections given new situations of interest and answer "what if" questions. The most appropriate algorithm, in terms of training speed and memory storage requirements, is clearly the Levenberg

  20. Ad-hoc Content-based Queries and Data Analysis for Virtual Observatories Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aquilent, Inc. proposes to support ad-hoc, content-based query and data retrieval from virtual observatories (VxO) by developing 1) Higher Order Query Services that...

  1. 基于UWB技术的Ad Hoc移动网络%The Mobile Ad Hoc Network Based on UWB

    Institute of Scientific and Technical Information of China (English)

    王继志; 王英龙; 王美琴

    2005-01-01

    随着Ad Hoc移动网络的发展和UWB技术的逐步成熟,研究采用UWB技术对Ad Hoc移动网络协议带来的影响,就变得非常迫切而且很有意义.本文简单介绍了UWB技术,探讨了采用UWB技术的Ad Hoc移动网络在网络协议方面需要做的改动和目前的研究成果,并描述了其应用前景.

  2. EBAA: An efficient broadcast authentication scheme for ADS-B communication based on IBS-MR

    Directory of Open Access Journals (Sweden)

    Yang Haomiao

    2014-06-01

    Full Text Available Automatic dependent surveillance-broadcast (ADS-B systems can broadcast satellite-based aircraft position, identification, etc., periodically, and are now on track to replace radar to become the backbone of next-generation air traffic management (ATM systems. However, ADS-B systems suffer severe cyber-security problems due to the broadcast-type data link and the lack of designed-in security measures. Especially, since ADS-B messages are unauthenticated, it is easy to insert fake aircraft into a system via spoofing or insertion of false messages. Unfortunately, the authentication for ADS-B messages has not yet been well studied. In this paper, based on identity-based signature with message recovery (IBS-MR, an efficient broadcast authentication scheme for ADS-B messages is proposed. The security analysis demonstrates that the scheme can achieve authenticity and integrity of ADS-B broadcast messages, as well as adaptive evolution of broadcasters’ private keys. The performance evaluation shows that the scheme is computationally efficient for typical avionics devices with limited resources. Furthermore, the scheme achieves low communication overhead since broadcast messages can be recovered from signatures, and thus it is suitable for low-bandwidth ADS-B data link.

  3. An Efficient Quality of Service Based Routing Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Tapan Kumar Godder

    2011-05-01

    Full Text Available Ad-hoc network is set up with multiple wireless devices without any infrastructure. Its employment is favored in many environments. Quality of Service (QoS is one of the main issues for any network and due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service (QoS is extremely a challenging task. It is modeled as a multi-layer problem and is considered in both Medium Access Control (MAC and routing layers for ad hoc networks. Ad-hoc On-demand Distance Vector (AODV routing protocol is one of the most used and popular reactive routing protocols in ad-hoc networks. This paper proposed a new protocol QoS based AODV (QAODV which is a modified version of AODV.

  4. Analysis of Fuzzy Logic Based Intrusion Detection Systems in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    A. Chaudhary

    2014-01-01

    Full Text Available Due to the advancement in wireless technologies, many of new paradigms have opened for communications. Among these technologies, mobile ad hoc networks play a prominent role for providing communication in many areas because of its independent nature of predefined infrastructure. But in terms of security, these networks are more vulnerable than the conventional networks because firewall and gateway based security mechanisms cannot be applied on it. That’s why intrusion detection systems are used as keystone in these networks. Many number of intrusion detection systems have been discovered to handle the uncertain activity in mobile ad hoc networks. This paper emphasized on proposed fuzzy based intrusion detection systems in mobile ad hoc networks and presented their effectiveness to identify the intrusions. This paper also examines the drawbacks of fuzzy based intrusion detection systems and discussed the future directions in the field of intrusion detection for mobile ad hoc networks.

  5. Similarity-Based Clustering Strategy for Mobile Ad Hoc Multimedia Databases

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2005-01-01

    Full Text Available Multimedia data are becoming popular in wireless ad hoc environments. However, the traditional content-based retrieval techniques are inefficient in ad hoc networks due to the multiple limitations such as node mobility, computation capability, memory space, network bandwidth, and data heterogeneity. To provide an efficient platform for multimedia retrieval, we propose to cluster ad hoc multimedia databases based on their semantic contents, and construct a virtual hierarchical indexing infrastructure overlaid on the mobile databases. This content-aware clustering scheme uses a semantic-aware framework as the theoretical foundation for data organization. Several novel techniques are presented to facilitate the representation and manipulation of multimedia data in ad hoc networks: 1 using concise distribution expressions to represent the semantic similarity of multimedia data, 2 constructing clusters based on the semantic relationships between multimedia entities, 3 reducing the cost of content-based multimedia retrieval through the restriction of semantic distances, and 4 employing a self-adaptive mechanism that dynamically adjusts to the content and topology changes of the ad hoc networks. The proposed scheme is scalable, fault-tolerant, and efficient in performing content-based multimedia retrieval as demonstrated in our combination of theoretical analysis and extensive experimental studies.

  6. An Effective Capacity Estimation Scheme in IEEE802.11-based Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    H. Zafar

    2012-11-01

    Full Text Available Capacity estimation is a key component of any admission control scheme required to support quality of serviceprovision in mobile ad hoc networks. A range of schemes have been previously proposed to estimate residualcapacity that is derived from window-based measurements of channel estimation. In this paper a simple and improvedmechanism to estimate residual capacity in IEEE802.11-based ad hoc networks is presented. The scheme proposesthe use of a ‘forgiveness’ factor to weight these previous measurements and is shown through simulation-basedevaluation to provide accurate utilizations estimation and improved residual capacity based admission control.

  7. Ad hoc distributed mutual exclusion algorithm based on token-asking

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng; Liu Xin song; Li Mei'an

    2007-01-01

    The solution of distributed mutual exclusion is difficult in Ad hoc networks owing to dynamic topologies and mobility.Based on the analysis of the properties of Ad hoc networks and the disadvantages of the traditional algorithms, an improved Ad hoc system model was given and a novel algorithm was presented as AHDME (Ad Hoc Distributed Mutual Exclusion); it was based on the token-asking algorithms.It utilized broadcast to search for the token and to decrease the message complexity of multi-hop Ad hoc networks.Lamport's timestamp was improved to ensure the time sequence and to prevent nodes from starvation.When compared to traditional algorithms, AHDME does not require the fixed size of request queues and the global system information, which adapts itself to the frequent arrival/departures and the limited computing capability of nodes in Ad hoc networks.Performance analysis and simulation results show that the AHDME algorithm has low message complexity, small space complexity, and short response delay.

  8. A MOBILE AGENT BASED INTRUSION DETECTION SYSTEM ARCHITECTURE FOR MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    Binod Kumar Pattanayak

    2014-01-01

    Full Text Available Applications of Mobile Ad Hoc Networks (MANETs have become extensively popular over the years among the researchers. However, the dynamic nature of MANETs imposes a set of challenges to its efficient implementation in practice. One of such challenges represents intrusion detection and prevention procedures that are intended to provide secured performance of ad hoc applications. In this study, we introduce a mobile agent based intrusion detection and prevention architecture for a clustered MANET. Here, a mobile agent resides in each cluster of the ad hoc network and each cluster runs a specific application at any point of time. This application specific approach makes the network more robust to external intrusions directed at the nodes in an ad hoc network.

  9. Hybrid Packet-Pheromone-Based Probabilistic Routing for Mobile Ad Hoc Networks

    Science.gov (United States)

    Kashkouli Nejad, Keyvan; Shawish, Ahmed; Jiang, Xiaohong; Horiguchi, Susumu

    Ad-Hoc networks are collections of mobile nodes communicating using wireless media without any fixed infrastructure. Minimal configuration and quick deployment make Ad-Hoc networks suitable for emergency situations like natural disasters or military conflicts. The current Ad-Hoc networks can only support either high mobility or high transmission rate at a time because they employ static approaches in their routing schemes. However, due to the continuous expansion of the Ad-Hoc network size, node-mobility and transmission rate, the development of new adaptive and dynamic routing schemes has become crucial. In this paper we propose a new routing scheme to support high transmission rates and high node-mobility simultaneously in a big Ad-Hoc network, by combining a new proposed packet-pheromone-based approach with the Hint Based Probabilistic Protocol (HBPP) for congestion avoidance with dynamic path selection in packet forwarding process. Because of using the available feedback information, the proposed algorithm does not introduce any additional overhead. The extensive simulation-based analysis conducted in this paper indicates that the proposed algorithm offers small packet-latency and achieves a significantly higher delivery probability in comparison with the available Hint-Based Probabilistic Protocol (HBPP).

  10. Location Based Throughput Maximization Routing in Energy Constrained Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    V. Sumathy

    2006-01-01

    Full Text Available In wireless Ad-hoc network, power consumption becomes an important issue due to limited battery power. One of the reasons for energy expenditure in this network is irregularly distributed node pattern, which impose large interference range in certain area. To maximize the lifetime of ad-hoc mobile network, the power consumption rate of each node must be evenly distributed and the over all transmission range of each node must be minimized. Our protocol, Location based throughput maximization routing in energy constrained Ad-hoc network finds routing paths, which maximize the lifetime of individual nodes and minimize the total transmission energy consumption. The life of the entire network is increased and the network throughput is also increased. The reliability of the path is also increased. Location based energy constrained routing finds the distance between the nodes. Based on the distance the transmission power required is calculated and dynamically reduces the total transmission energy.

  11. Design of C Band Phase Detector Based on AD8302%基与AD8302的C波段鉴相器设计

    Institute of Scientific and Technical Information of China (English)

    刘聪; 李少甫

    2014-01-01

    In order to detect the phase difference between the C band microwaves which we need to do power combining, the paper introduces the chip AD8302 which usually be used to measure the gain/loss and phase in RF/IF system. Then the paper re-ports the design of a C band phase detector that based on the phase measurement function of AD 8302. First, the front-end of fre-quency conversion circuit is introduced, it converts the C band input microwaves to appropriate frequency that can be processed directly in AD8302. Then, AD8302 module measures the phase difference. The last, the measurement result well agrees with the datasheet of the chip.%为解决C波段功率合成中相位测量的问题,该文介绍了一种用于RF/IF幅度和相位测量的AD8302芯片,并利用它的鉴相功能实现了一款C波段的鉴相器的设计。首先采用前端变频电路将信号频率变换到AD8302可以处理范围内,然后利用AD8302进行相位差的测量。测试结果与芯片说明手册的鉴相结果相吻合。

  12. Fuzzy-Based Sensor Fusion for Cognitive Radio-Based Vehicular Ad Hoc and Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mohammad Jalil Piran

    2015-01-01

    Full Text Available In wireless sensor networks, sensor fusion is employed to integrate the acquired data from diverse sensors to provide a unified interpretation. The best and most salient advantage of sensor fusion is to obtain high-level information in both statistical and definitive aspects, which cannot be attained by a single sensor. In this paper, we propose a novel sensor fusion technique based on fuzzy theory for our earlier proposed Cognitive Radio-based Vehicular Ad Hoc and Sensor Networks (CR-VASNET. In the proposed technique, we considered four input sensor readings (antecedents and one output (consequent. The employed mobile nodes in CR-VASNET are supposed to be equipped with diverse sensors, which cater to our antecedent variables, for example, The Jerk, Collision Intensity, and Temperature and Inclination Degree. Crash_Severity is considered as the consequent variable. The processing and fusion of the diverse sensory signals are carried out by fuzzy logic scenario. Accuracy and reliability of the proposed protocol, demonstrated by the simulation results, introduce it as an applicable system to be employed to reduce the causalities rate of the vehicles’ crashes.

  13. 基于OPNET的Ad Hoc网络FSR路由协议的研究%Study of OPNET-Based FSR Routing Protocol in Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    郭静

    2013-01-01

      This paper is about how to achieve the development and implementation of FSR routing protocol in Ad hoc network based on OPNET simulation framework. The analysis of the routing protocol FSR based on table-driven is followed by the implementation of the protocol via OPNET modeling simulation tool in terms of Ad hoc network features. The application prospect of FSR in Ad hoc network is obtained through the comparison of performances such as time delay and load of FSR, AODV and OLSR.%  本文阐述了基于OPNET仿真框架下,如何实现Ad hoc网络中FSR路由协议的开发实现。针对Ad hoc网络特点的分析,分析基于表驱动的路由协议FSR,并通过OPNET建模仿真工具来实现该协议。通过 FSR 与 AODV、OLSR 进行时延和负载方面的性能比较,得出 FSR在Ad hoc网络中应用前景。

  14. A 10-bit low power SAR A/D converter based on 90 nm CMOS

    Institute of Scientific and Technical Information of China (English)

    Tong Xingyuan; Yang Yintang; Zhu Zhangming; Xiao Yan; Chen Jianming

    2009-01-01

    Traditional and some recently reported low power, high speed and high resolution approaches for SAR A/D converters are discussed. Based on SMIC 65 nm CMOS technology, two typical low power methods reported in previous works are validated by circuit design and simulation. Design challenges and considerations for high speed SAR A/D converters are presented. Moreover, an R-C combination based method is also addressed and a 10-bit SAR A/D converter with this approach is implemented in SMIC 90 nm CMOS process. The DNL and INL are measured to be less than 0.31 LSB and 0.59 LSB respectively. With an input frequency of 420 kHz at 1 MS/s sampling rate, the SFDR and ENOB are measured to be 67.6 dB and 9.46 bits respectively, and the power dissipation is measured to be just 3.17 mW.

  15. Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit

    Directory of Open Access Journals (Sweden)

    Chabowski Konrad

    2015-03-01

    Full Text Available As it contains elements of complete digital impedance meter, the AD5933 integrated circuit is an interesting solution for impedance measurements. However, its use for measurements in a wide range of impedances and frequencies requires an additional digital and analogue circuitry. This paper presents the design and performance of a simple impedance meter based on the AD5933 IC. Apart from the AD5933 IC it consists of a clock generator with a programmable prescaler, a novel DC offset canceller for the excitation signal based on peak detectors and a current to voltage converter with switchable conversion ratios. The authors proposed a simple method for choosing the measurement frequency to minimalize errors resulting from the spectral leakage and distortion caused by a lack of an anti-aliasing filter in the DDS generator. Additionally, a novel method for the AD5933 IC calibration was proposed. It consists in a mathematical compensation of the systematic error occurring in the argument of the value returned from the AD5933 IC as a result. The performance of the whole system is demonstrated in an exemplary measurement.

  16. Test marketing for value-added root and tuber based products in ...

    African Journals Online (AJOL)

    Test marketing for value-added root and tuber based products in Ikwuano local ... In terms of percentage volume of sales, Chin-Chin ranked 1st followed by ginger ... This will create markets and increase demand thereby eliminating wastage of ...

  17. The Value Simulation-Based Learning Added to Machining Technology in Singapore

    Science.gov (United States)

    Fang, Linda; Tan, Hock Soon; Thwin, Mya Mya; Tan, Kim Cheng; Koh, Caroline

    2011-01-01

    This study seeks to understand the value simulation-based learning (SBL) added to the learning of Machining Technology in a 15-week core subject course offered to university students. The research questions were: (1) How did SBL enhance classroom learning? (2) How did SBL help participants in their test? (3) How did SBL prepare participants for…

  18. Pseudo-Coherence-Based MVDR Beamformer for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    . This paper proposes minimum variance distortionless response filtering based on multichannel pseudo-coherence for speech enhancement with ad hoc microphone arrays. This method requires neither position information nor control of the trade-off used in the distortion weighted methods. Furthermore, certain...

  19. 基于链路质量的Ad hoc路由协议研究%Research on Hoc Ad Routing Protocol Based on Link Quality

    Institute of Scientific and Technical Information of China (English)

    王柯; 刘亮

    2015-01-01

    Ad hoc是近年来热门的无线分组网络。路由协议是Ad hoc网络的关键技术,决定了Ad hoc网络的寻址效率并为数据传输提供可靠的QoS保证。在小型化网络、低带宽条件下,使用改进的基于链路状态路由协议可以有效的提高寻址效率和网络可靠性。%Hoc Ad is a popular wireless packet network in recent years. Routing protocol is the key technology of hoc Ad network, which determines the efifciency of hoc Ad network and provides reliable QoS guarantee for data transmission. Under the condition of small network and low bandwidth, the improved routing protocol based on link state can effectively improve the efifciency and the reliability of the network.

  20. Ad hoc网中基于簇结构的认证服务方案%Authentication Service Plan Based on the Cluster Structure in Ad hoc Network

    Institute of Scientific and Technical Information of China (English)

    余海芸

    2011-01-01

    The Ad Hoc network is a kind of a special wireless mobile network.In this network,all the nodes are the same,need not on the central control node.This paper discusses the present with extensive application of layered structure-cluster structure analyzed.In this paper, first Ad Hoc network the corresponding to Ad Hoc analysis,then,the main network application technology, and common problem is discussed, finally discusses the cluster structure based on the certification service plan.%Ad Hoc网络是一种比较特殊的无线移动网络。在此网络中,所有的节点都是一样的,不用设置中心控制节点。本文首先对Ad Hoc网络进行了相应分析,然后对Ad Hoc网络中的主要应用技术和常见问题进行了阐述,最后论述了基于簇结构的认证服务方案。

  1. A QoS Routing Protocol based on Available Bandwidth Estimation for Wireless Ad Hoc Networks

    CERN Document Server

    Kaaniche, Heni; Frikha, Mounir; Kamoun, Farouk

    2011-01-01

    At the same time as the emergence of multimedia in mobile Ad hoc networks, research for the introduction of the quality of service (QoS) has received much attention. However, when designing a QoS solution, the estimation of the available resources still represents one of the main issues. This paper suggests an approach to estimate available resources on a node. This approach is based on the estimation of the busy ratio of the shared canal. We consider in our estimation the several constraints related to the Ad hoc transmission mode such as Interference phenomena. This approach is implemented on the AODV routing protocol. We call AODVwithQOS our new routing protocol. We also performed a performance evaluation by simulations using NS2 simulator. The results confirm that AODVwithQoS provides QoS support in ad hoc wireless networks with good performance and low overhead.

  2. Service for fault tolerance in the Ad Hoc Networks based on Multi Agent Systems

    Directory of Open Access Journals (Sweden)

    Ghalem Belalem

    2011-02-01

    Full Text Available The Ad hoc networks are distributed networks, self-organized and does not require infrastructure. In such network, mobile infrastructures are subject of disconnections. This situation may concern a voluntary or involuntary disconnection of nodes caused by the high mobility in the Ad hoc network. In these problems we are trying through this work to contribute to solving these problems in order to ensure continuous service by proposing our service for faults tolerance based on Multi Agent Systems (MAS, which predict a problem and decision making in relation to critical nodes. Our work contributes to study the prediction of voluntary and involuntary disconnections in the Ad hoc network; therefore we propose our service for faults tolerance that allows for effective distribution of information in the Network by selecting some objects of the network to be duplicates of information.

  3. Predicting Reaction Mechanisms and Potentials in Acid and Base from Self-Consistent Quantum Theory: H(ads) and OH(ads) Deposition on the Pt(111) Electrode.

    Science.gov (United States)

    Zhao, Meng; Anderson, Alfred B

    2016-02-18

    It has been shown recently that when reactants and products are well modeled within a comprehensive self-consistent theory for the electrochemical interface, accurate predictions are possible for reversible potentials, Urev, in acid electrolyte for reactions such as reduction of H(+)(aq) to form under potential deposited H(ads) and oxidation of an OH bond of H2O(ads) to deposit OH(ads). Predictions are based on calculated Gibbs energies for the reactant and product being equal at the reversible potential, which is the potential at the crossing point for reaction and product Gibbs energies, plotted as functions of electrode potential. In this Letter, it is demonstrated that the same capability holds for these reactions in basic electrolyte. This demonstration opens up the opportunity for predictions of reversible potentials and mechanisms for other electrocatalytic reactions in base.

  4. 基于身份的Ad Hoc网密钥管理方案%Identity-based key management scheme for Ad Hoc network

    Institute of Scientific and Technical Information of China (English)

    孙梅; 赵兵

    2012-01-01

    According to the characteristics of Ad Hoc networks, such as mobility and self-organization, an identity-based key management scheme for Ad Hoc networks was proposed. In the paper, by the method of secure distributed key generation based on threshold cryptography, the interior members of Ad Hoc networks collaborated to conduct the system private key. Compared with the existent protocol, the proposed scheme, does not require the fixed structure of service nodes, and service nodes can dynamically join and leave network. At the same time, the system key is updatable among service nodes. The analytical results show the proposed scheme is flexible and secure, and it is suitable for Mobile Ad Hoc Network ( MANET).%鉴于Ad Hoc网络的可移动、自组织性等优点,提出了一种适用于Ad Hoc网络的基于身份的密钥管理方案,所提方案在门限密码学的基础上以完全分布化方式建立系统密钥.与已有的Ad Hoc网络密钥管理方案相比,它不需要固定的密钥服务节点组,密钥服务节点可以动态加入和撤离,而且系统密钥在密钥服务节点组内还可以动态更新.分析结果表明所提方案具有灵活、安全的特点,较好地适应了移动自组网(MANET).

  5. Analysis and Proposal of Position-Based Routing Protocols for Vehicular Ad Hoc Networks

    Science.gov (United States)

    Okada, Hiraku; Takano, Akira; Mase, Kenichi

    One of the most promising applications of a mobile ad hoc network is a vehicular ad hoc network (VANET). Each vehicle is aware of its position information by GPS or other methods, so position-based routing is a useful approach in VANET. The position-based routing protocol can be classified roughly into a next-hop forwarding method and a directed flooding method. We evaluate performance of both methods by analytic approach and compare them in this paper. From the evaluation results, we conclude that it is effective for the position-based routing to choose either the next-hop forwarding method or the directed flooding method according to the environment. Then we propose the hybrid transmission method which can select one of them according to the environment, and clarify that the proposed method can keep the packet delivery ratio at a high level and reduce the delay time.

  6. GBP-WAHSN: A Group-Based Protocol for Large Wireless Ad Hoc and Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Jaime Lloret; Miguel Garcia; Jesus Tomás; Fernando Boronat

    2008-01-01

    Grouping nodes gives better performance to the whole network by diminishing the average network delay and avoiding unnecessary message for warding and additional overhead. Many routing protocols for ad-hoc and sensor network shave been designed but none of them are based on groups. In this paper, we will start defining group-based topologies,and then we will show how some wireless ad hoc sensor networks (WAHSN) routing protocols perform when the nodes are arranged in groups. In our proposal connections between groups are established as a function of the proximity of the nodes and the neighbor's available capacity (based on the node's energy). We describe the architecture proposal, the messages that are needed for the proper operation and its mathematical description. We have also simulated how much time is needed to propagate information between groups. Finally, we will show a comparison with other architectures.

  7. Building Asphalt Pavement with SBS-based Compound Added Using a Dry Process in Greenland

    DEFF Research Database (Denmark)

    Lee, Hosin; Kim, Yongjoo; Geisler, Nivi

    2009-01-01

    heavy traffic and severe weather conditions in Greenland. Based on the initial set of strain data collected under the slow-moving loader right after construction, the highest strain value was observed from the test section with the highest amount of SBS-based compound. The increased amount of SBS......-based compound seemed to affect the asphalt mix to become more flexible under the heavy loads. By adding SBS-based compound to asphalt mixtures using a “dry” process, it is expected that the pavement would become more resistant to rutting than a typical asphalt mixture used in Greenland while enduring its arctic...... weather....

  8. Optimal congestion control algorithm for ad hoc networks: Penalty function-based approach

    Institute of Scientific and Technical Information of China (English)

    XU Wet-qiang; WU Tie-jun

    2006-01-01

    In this paper, based on the inherent characteristic of the contention relation between flows in ad hoc networks, we introduce the notion of the link's interference set, extend the utility maximization problem representing congestion control in wireline networks to ad hoc networks, apply the penalty function approach and the subgradient method to solve this problem, and propose the congestion control algorithm Penalty function-based Optical Congestion Control (POCC) which is implemented in NS2 simulator. Specifically, each link transmits periodically the information on its congestion state to its interference set; the session at each source adjusts the transmission rate based on the optimal tradeoffbetween the utility value and the congestion level which the interference set of the links that this session goes though suffers from. MATLAB-based simulation results showed that POCC can approach the globally optimal solution. The NS2-based simulation results showed that POCC outperforms default TCP and ATCP to achieve efficient and fair resource allocation in ad hoc networks.

  9. Nuovi indicatori di sbilanciamento e prevedibilità nei disegni sequenziali randomizzati: confronti fra 'biased coin designs' diversi

    Directory of Open Access Journals (Sweden)

    Alessandro Baldi Antognini

    2007-10-01

    Full Text Available Efron's (1971 Biased Coin Design is a well-known randomization technique of sequential clinical trials for comparing two treatments in the absence of prognostic factors that helps neutralize selection bias while keeping the experiment fairly balanced., Efron's idea has been extended to other types of procedures, but only their asymptotic properties as regards selection bias and imbalance are considered in the literature. In this paper we define new indicators of selection bias and imbalance of the sequential experiment, based on the probability of the "worst possible scenario", which can be computed explicitly for different designs and for any finite sample size n without resorting to simulations. Making use of these measures, we compare the main existing designs with the Adjustable Biased Coin Design (ABCD, recently introduced by two of the present authors. In general, the greater flexibility of the ABCD allows one to choose a sequential procedure that turns out, for all n, to be less predictable and more balanced than the other "biased coin" designs.

  10. An Agent Based Intrusion Detection Model for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    B. M. Reshmi

    2006-01-01

    Full Text Available Intrusion detection has over the last few years, assumed paramount importance within the broad realm of network security, more so in case of wireless mobile ad hoc networks. The inherently vulnerable characteristics of wireless mobile ad hoc networks make them susceptible to attacks in-spite of some security measures, and it may be too late before any counter action can take effect. As such, there is a need to complement traditional security mechanisms with efficient intrusion detection and response systems. This paper proposes an agent-based model to address the aspect of intrusion detection in cluster based mobile wireless ad hoc network environment. The model comprises of a set of static and mobile agents, which are used to detect intrusions, respond to intrusions, and distribute selected and aggregated intrusion information to all other nodes in the network in an intelligent manner. The model is simulated to test its operation effectiveness by considering the performance parameters such as, detection rate, false positives, agent overheads, and intrusion information distribution time. Agent based approach facilitates flexible and adaptable security services. Also, it supports component based software engineering components such as maintainability, reachability, reusability, adaptability, flexibility, and customization.

  11. Trust-based hexagonal clustering for efficient certificate management scheme in mobile ad hoc networks

    Indian Academy of Sciences (India)

    V S JANANI; M S K MANIKANDAN

    2016-10-01

    The wireless and dynamic nature of mobile ad hoc networks (MANET) render them more vulnerable to security attacks. However, providing a security mechanism implicitly has been a major challenge in such an ad-hoc environment. Certificate management plays an important role in securing an ad-hoc network.Certificate assignment, verification, and revocation complexity associated with the Public Key Infrastructure (PKI) framework is significantly large. Smaller the size of the network lesser will be the certificate management complexity. However, smaller the size, large will be the overall infrastructural cost, and also larger will be the overall redundant certificates due to multiple certificate assignment at the boundary regions, that in turn affects the prompt and accurate certificate revocation. By taking these conflicting requirements into consideration, we propose the trust-based hexagonal clustering for an efficient certificate management (THCM) scheme, to bear an absolutely protected MANET Disparate to the existing clustering techniques, we present a hexagonal geographicclustering model with Voronoi technique where trust is accomplished. In particular, to compete against attackers, we initiate a certificate management strategy in which certificate assignment, verification, and revocation are carried out efficiently. The performance of THCM is evaluated by both simulation and empirical analysis in terms of effectiveness of revocation scheme (with respect to revocation rate and time), security, and communication cost. Besides, we conduct a mathematical analysis of measuring the parameters obtained from the two platforms in multiple times. Relevant results demonstrate that our design is efficient to guarantee a secured mobile ad hoc network.

  12. Quasi-ADS-B Based UAV Conflict Detection and Resolution to Manned Aircraft

    Directory of Open Access Journals (Sweden)

    Chin E. Lin

    2015-01-01

    Full Text Available A Conflict Detection and Resolution (CD&R system for manned/unmanned aerial vehicle (UAV based on Automatic Dependent Surveillance-Broadcast (ADS-B concept is designed and verified in this paper. The 900 MHz XBee-Pro is selected as data transponder to broadcast flight information among participating aircraft in omnirange. Standard Compact Position Report (CPR format packet data are automatically broadcasted by ID sequencing under Quasi-ADS-B mechanism. Time Division Multiple Access (TDMA monitoring checks the designated time slot and reallocates the conflict ID. This mechanism allows the transponder to effectively share data with multiple aircraft in near airspace. The STM32f103 microprocessor is designed to handle RF, GPS, and flight data with Windows application on manned aircraft and ground control station simultaneously. Different conflict detection and collision avoidance algorithms can be implemented into the system to ensure flight safety. The proposed UAV/CD&R using Quasi-ADS-B transceiver is tested using ultralight aircraft flying at 100–120 km/hr speed in small airspace for mission simulation. The proposed hardware is also useful to additional applications to mountain hikers for emergency search and rescue. The fundamental function by the proposed UAV/CD&R using Quasi-ADS-B is verified with effective signal broadcasting for surveillance and efficient collision alert and avoidance performance to low altitude flights.

  13. Towards Trust-based Cognitive Networks: A Survey of Trust Management for Mobile Ad Hoc Networks

    Science.gov (United States)

    2009-06-01

    Coast, Australia, 21-26 May 2006. [4] P. Albers , O. Camp, J.-M. Percher, B. Jouga, L. Mé, and R. Puttini, “Security in Ad Hoc Networks: a General...10th Euromicro Workshop on Parallel, Distributed, and Network-based Processing, Canary Islands, Spain, Jan . 2002, pp. 403-410. [7] S. Buchegger and...DETECTION Albers et al.(2002) [4] -Direct observation for anomaly detection or misuse detection -General misbehaving nodes No experimental results

  14. Intelligent Security Auditing Based on Access Control of Devices in Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    XU Guang-wei; SHI You-qun; ZHU Ming; WU Guo-wen; CAO Qi-ying

    2006-01-01

    Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy and operating regulation and used to identify abnormal operation. Model of security auditing based on access control of devices will be advanced to register sign of devices and property of event of access control and to audit those actions. In the end, the model is analyzed and simulated.

  15. Added Value in the Rural Agro-industries: an analysis based on the Agricultural Census data

    OpenAIRE

    2012-01-01

    The paper discusses the added value in the Brazilian rural agro-industries. The information is derived from tabulations based on Agricultural Census microdata, which allowed us to construct a sectorial and macro-regional comparison. Among the wide set of manufacturing and processing activities measured by the census, we selected nine processed products in the rural establishments (aguardente, jams and jellies, cassava flour, corn meal, bread, cheese and cream cheese, rapadura, sausage and tap...

  16. Mortalidade por tuberculose e indicadores sociais no município do Rio de Janeiro Tuberculosis mortality and social indicatory in Rio de Janeiro city

    Directory of Open Access Journals (Sweden)

    Genésio Vicentin

    2002-01-01

    Full Text Available Este artigo estuda a mortalidade por tuberculose no município do Rio de Janeiro ocorrida no ano de 1991 em comparação com indicadores sociais. Utilizou-se o software SPSS 8.0 - 1997 na análise estatística dos dados, que mostrou a existência de correlação entre a maioria dos indicadores socioeconômicos estudados e o coeficiente de mortalidade por tuberculose por 100 mil habitantes/ano. Apresentaram correlação significativa e direta os indicadores: índice de Robin Hood, razão de renda entre os 10% mais ricos e os 40% mais pobres e proporção de chefes de família com renda média entre um e dois salários mínimos. A correlação foi inversa e significativa com os indicadores: proporção de residentes com mais de 10 anos com curso superior, área média por domicílio, número de cômodos por domicílio, renda média em salários mínimos, e proporção de chefes de família com rendas entre 10-15, 16-20 e acima de 20 salários mínimos. Para a apresentação destes indicadores usou-se mapas do município, categorizados e distribuídos por Regiões Administrativas, revelando distintos Rios de Janeiro, quando este é visto sob o ângulo social: da doença, ou de vários outros indicadores.Regional tuberculosis mortality levels and their Rio de Janeiro City principals social indicatories at year 1991 have been compared in this study. Software SPSS 8.0 - 1997 was applied on making statistical data analysis, and have disclosed a present correlation among most indicative socioeconomics trends and the annual tuberculosis mortality coeficient/100 thousand inhabitants. Others social indicatives than Robin Hood index, 10% more rich to 40% more poor reason, head of family proportion wich 1-2 minimum wage monthly gain, disclosed imediate and significative statistical assurance level. In reverse and significative statistical assurance level, resident proportion with more 10 years old that have superior course, house área average, room average

  17. The study of urban systems by indicators. State of the art and implementation problems; Lo studio dei sistemi urbani attraverso indicatori. Stato dell'arte e problematiche operative

    Energy Technology Data Exchange (ETDEWEB)

    Del Ciello, R.; Napoleoni, S. [ENEA, Divisione Caratterizzazione dell' Ambiente e del Territorio, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy)

    2001-07-01

    The purpose of this work is to define the state of the art about the problem of the indicators and their capability in reading and foreseeing the urban complexity. Therefore, the theoretical elaborations and the suggestions developed in the report try to convert the different contributions in the Italian and international literature in a frame-work, focusing on those arguments which assume a key role in the study of the urban areas: (a) the problematic definition of the administrative, physics and functional boarders of the cities; (b) the selection of the indicators that describe the urban areas; (c) the description and quality of life and of environment quality in the cities; (d) the sustainability in urban areas. [Italian] Il lavoro si propone di delineare lo stato dell'arte sul problema degli indicatori e sulla loro capacita' di leggere e prevedere la complessita' urbana. Le elaborazioni teoriche e i suggerimenti metodologici sviluppati nel rapporto tentano dunque di tradurre in protocolli di lavoro i diversi contributi prodotti negli ultimi anni nella letteratura italiana e internazionale concentrando in particolare l'attenzione su quei temi che all'interno dello studio dei sistemi urbani assumono un ruolo chiave: (a) la problematica definizione dei confini amministrativi, fisici e funzionali delle citta'; (b) la selezione degli indicatori che descrivono con piu' efficacia il sistema urbano; (c) le dimensioni e la misura della qualita' della vita e dell'ambiente nelle citta'; (d) la sostenibilita' all'interno dei sistemi urbani.

  18. Merck Ad5艾滋病疫苗的研究进展%Progress in Research on Merck's Ad5-based AIDS Vaccine

    Institute of Scientific and Technical Information of China (English)

    刘强

    2011-01-01

    安全有效的疫苗是艾滋病防治的有效手段.上世纪90年代,Merck公司开始研发腺病毒5型(Ad5)载体T细胞概念艾滋病疫苗.2007年9月,在II b期临床观察中宣告失败,给疫苗学界带来沉重打击.本文就Merck Ad5艾滋病疫苗的构建、临床前期和I、Ⅱ期临床观察以及学术界对其失败原因的分析作一综述.%An effective vaccine remains the primary goal for a comprehensive strategy to curb the global HIV epidemic. Merck began to develop adenovirus type 5 ( Ad5 )-based AIDS vaccine in 1990s. In 2007, Merck and NIAID announced that a phase Ⅱb clinical trial of an Ad5-based AIDS vaccine was discontinued after an interim analysis revealed that the vaccine did not work. The vaccine construction, preclinical and clinical trials and causes of failure are reviewed in this paper.

  19. Design of ADS8322 Sampling Controller Based on Verilog HDL%基于Verilog HDL的ADS8322转换控制器设计

    Institute of Scientific and Technical Information of China (English)

    李文桐; 黄金; 孙先松

    2011-01-01

    According to the project needs,the Cyclone Ⅱ series EP2C8 field programmable logic gate array(FPGA) is used to control 16bit high-speed analog-to-digital conversion chip ADS8322,we designed a kind of ADS8322 sampling control logic circuit based on Verilog hardware description languages.This paper discuss the characteristics and work timing of ADS8322 in detail,realizing the control logic by finite state machine.It also gives the function simulation waveform of sampling control circuit in Quartus9.1 software environment.Testing this system in practical,it is proved that the method is simple and effective and reliable.It can be used to control High-speed A/D.%根据项目需求,采用Cyclone II系列EP2C8现场可编程逻辑门阵列(FPGA)作为控制核心,对16位高速模数转换芯片ADS8322进行控制,设计了一种基于Verilog硬件描述语言的ADS8322采样控制逻辑电路,该文详细阐明了ADS8322的特点和工作时序,采用有限状态机,实现了控制器电路的时序逻辑。同时给出采样控制电路在Quartus II 9.1软件环境下的功能仿真波形。通过实际电路测试,证明该设计方案简洁、有效、可靠,同时可方便应用于其他类似的高速AD转换控制。

  20. Fault Tolerant Mechanism for Multimedia Flows in Wireless Ad Hoc Networks Based on Fast Switching Paths

    Directory of Open Access Journals (Sweden)

    Juan R. Diaz

    2014-01-01

    Full Text Available Multimedia traffic can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. This architecture is focused on decreasing quality of service (QoS parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia flow crossing the wireless ad hoc network when there is a node failure. The algorithm can run independently for each multimedia flow. The main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. This paper provides the designed protocol, the analytical model of the algorithm, and a software application developed to test its performance in a real laboratory.

  1. Key Management Using Certificate-Based Cryptosystem in Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    LI Fa-gen; GAO Jun-tao; LIU Shuang-gen; HU Yu-pu

    2006-01-01

    This paper proposed a distributed key management approach by using the recently developed concepts of certificate-based cryptosystem and threshold secret sharing schemes. Without any assumption of prefixed trust relationship between nodes, the ad hoc network works in a self-organizing way to provide the key generation and key management services using threshold secret sharing schemes, which effectively solves the problem of single point of failure. The proposed approach combines the best aspects of identity-based key management approaches (implicit certification) and traditional public key infrastructure approaches (no key escrow).

  2. Magnetorheology of suspensions based on graphene oxide coated or added carbonyl iron microspheres and sunflower oil

    Science.gov (United States)

    Chen, Kaikai; Zhang, Wen Ling; Shan, Lei; Zhang, Xiangjun; Meng, Yonggang; Choi, Hyoung Jin; Tian, Yu

    2014-10-01

    Magnetorheological (MR) fluids based on carbonyl iron (CI) particles coated with graphene oxide (GO) and sunflower oils were studied and compared with MR fluids (MRFs) prepared with CI particles added with GO sheets. Adding GO sheets into CI had a negligible effect on the rheological properties of the MRF. Coating the spheres with GO markedly decreased the shear strength at high shear rates due to the remarkable lubricating function of the GO surface. Different behaviors were observed in the shear thickening phenomenon when the GO surface changed the mechanical interaction between particles. The results demonstrated the importance of the role of interparticle friction for MRF in shear mode and discussed the weak shear thickening phenomenon with fine lubricating coating layers and oils.

  3. A LOOP-BASED APPROACH IN CLUSTERING AND ROUTING IN MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Li Yanping; Wang Xin; Xue Xiangyang; C.K. Toh

    2006-01-01

    Although clustering is a convenient framework to enable traffic control and service support in Mobile Ad hoc NETworks (MANETs), it is seldom adopted in practice due to the additional traffic overhead it leads to for the resource limited ad hoc network. In order to address this problem, we proposed a loop-based approach to combine clustering and routing. By employing loop topologies, topology information is disseminated with a loop instead of a single node, which provides better robustness, and the nature of a loop that there are two paths between each pair of nodes within a loop suggests smart route recovery strategy. Our approach is composed of setup procedure, regular procedure and recovery procedure to achieve clustering, routing and emergent route recovering.

  4. Optical A/D Quantizer Scheme Based on Parallel Phase Modulators

    Institute of Scientific and Technical Information of China (English)

    LI Zheng

    2005-01-01

    A high-speed and high-resolution optical A/D quantizer is proposed. Its architecture is discussed. Bit circuits are built by using the phase modulators in parallel. Based on the different character of the half-wave voltage for every phase modulator and the polarized bias design of incident light, the RF input signal is coded and transmitted in the form of optical digital signal. According to the principle of the architecture, the high-resolution quantizers with 8-bit and 12-bit, et al. are built, which operate at 100 GS/s.Their quantization noise is invariable almost with bit circuits increasing. The simulation result of 4-bit A/D quantizer is also given.

  5. Bandwidth Estimation Problem & Solutions in IEEE 802.11 based Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Neeraj Gupta

    2012-11-01

    Full Text Available With the rise in multimedia applications in ad hoc networks it is necessary to ensure the quality of service support from network. The routers which may be mobile nodes in ad hoc networks should be able to evaluate the resources available in the network, prior to offering guarantees on delay, bandwidth or any other metric. Estimating the available bandwidth is often required before performing admission control, flows management, congestion control or routing based on bandwidth constraints so that before any new flow is admitted the existing flow does not degrade. Lot of work in terms of various tools and techniques has been proposed to evaluate the available bandwidth in last decade; no consensus has yet been arrived. We present a comprehensive review on the various state of art work proposed carried out in this area

  6. Cooperation in Carrier Sense Based Wireless Ad Hoc Networks - Part II: Proactive Schemes

    CERN Document Server

    Munari, Andrea; Zorzi, Michele

    2012-01-01

    This work is the second of a two-part series of papers on the effectiveness of cooperative techniques in non-centralized carrier sense-based ad hoc wireless networks. While Part I extensively discussed reactive cooperation, characterized by relayed transmissions triggered by failure events at the intended receiver, Part II investigates in depth proactive solutions, in which the source of a packet exploits channel state information to preemptively coordinate with relays in order to achieve the optimal overall rate to the destination. In particular, this work shows by means of both analysis and simulation that the performance of reactive cooperation is reduced by the intrinsic nature of the considered medium access policy, which biases the distribution of the available relays, locating them in unfavorable positions for rate optimization. Moreover, the highly dynamic nature of interference that characterizes non-infrastructured ad hoc networks is proved to hamper the efficacy and the reliability of preemptively ...

  7. String Theory on AdS Spaces

    NARCIS (Netherlands)

    de Boer, J.

    2000-01-01

    In these notes we discuss various aspects of string theory in AdS spaces. We briefly review the formulation in terms of Green-Schwarz, NSR, and Berkovits variables, as well as the construction of exact conformal field theories with AdS backgrounds. Based on lectures given at the Kyoto YITP Workshop

  8. 基于位置的Ad hoc网络路由协议研究%Study on Location-based Unicast Routing Protocol for Ad hoc Network

    Institute of Scientific and Technical Information of China (English)

    孟积渐; 刘禹

    2012-01-01

    基于位置的Ad hoc网络路由协议利用节点地理位置信息指导数据包的转发,具有可扩展性强,路由效率高等优点。分析了Ad hoc网络中基于位置的路由协议以及位置信息服务,对几种协议进行了分析比较,并指出了基于位置的路由协议的研究重点。%iLocation-based unicast routing protocol uses geographical location information of nodes to direct the forward of data package,superior to scalability and high efficiency in routing.In this paper,we introduced location-based unicast Routing Protocols and location information services for Ad hoc network.Analysed and compared several protocols,we pointed at the research emphasis on location-based unicast routing protocol.

  9. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    Science.gov (United States)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-10-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage ( I- V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  10. Design and R&D Progress of China Lead-Based Reactor for ADS Research Facility

    Directory of Open Access Journals (Sweden)

    Yican Wu

    2016-03-01

    Full Text Available In 2011, the Chinese Academy of Sciences launched an engineering project to develop an accelerator-driven subcritical system (ADS for nuclear waste transmutation. The China Lead-based Reactor (CLEAR, proposed by the Institute of Nuclear Energy Safety Technology, was selected as the reference reactor for ADS development, as well as for the technology development of the Generation IV lead-cooled fast reactor. The conceptual design of CLEAR-I with 10 MW thermal power has been completed. KYLIN series lead-bismuth eutectic experimental loops have been constructed to investigate the technologies of the coolant, key components, structural materials, fuel assembly, operation, and control. In order to validate and test the key components and integrated operating technology of the lead-based reactor, the lead alloy-cooled non-nuclear reactor CLEAR-S, the lead-based zero-power nuclear reactor CLEAR-0, and the lead-based virtual reactor CLEAR-V are under realization.

  11. Statistical-Based Joint Power Control for Wireless Ad Hoc CDMA Networks

    Institute of Scientific and Technical Information of China (English)

    ZHANGShu; RONGMongtian; CHENBo

    2005-01-01

    Current power control algorithm for CDMA-based ad hoc networks contains SIR and interference measurement, which is based on history information. However, for the traffics in today's or future's network, important statistical property is burstiness. As a consequence, the interference at a given receiving node may fluctuate dramatically. So the convergence speed of power control is not fast and the performance degrades. This paper presents a joint power control model. To a receiving node, all transmitting nodes assigned in same time slot adjust their transmitter power based on current information, which takes into account the adjustments of transmitter power of other transmitting nodes. Based on the joint power control model, this paper proposes a statisticalbased power control algorithm. Through this new algorithm, the interference is estimated more exactly. The simulation results indicated that the proposed power control algorithm outperforms the old algorithm.

  12. Adding Ajax

    CERN Document Server

    Powers, Shelley

    2007-01-01

    Ajax can bring many advantages to an existing web application without forcing you to redo the whole thing. This book explains how you can add Ajax to enhance, rather than replace, the way your application works. For instance, if you have a traditional web application based on submitting a form to update a table, you can enhance it by adding the capability to update the table with changes to the form fields, without actually having to submit the form. That's just one example.Adding Ajax is for those of you more interested in extending existing applications than in creating Rich Internet Applica

  13. A Layered Zone Routing Algorithm in Ad Hoc Network Based on Matrix of Adjacency Connection

    Institute of Scientific and Technical Information of China (English)

    XU Guang-wei; LI Feng; SHI Xiu-jin; HUO Jia-zhen

    2007-01-01

    The hybrid routing protocol has received more attention recently than the proactive and the reactive, especially for large-scale and highly dynamic connection, in mobile ad hoc network. A crucial reason is that zone-layered is being utilized in the complex systems. A hybrid routing algorithm which is layered zone based on adjacency connection(LZBAC) is put forward under the background of a few members in network with steady position and link. The algorithm modifies storage structure of nodes and improves routing mechanism. The theoretical analysis and simulation testing testify that the algorithm costs shorter time of route finding and less delay than others.

  14. A TDMA based media access control protocol for wireless ad hoc networks

    Science.gov (United States)

    Yang, Qi; Tang, Biyu

    2013-03-01

    This paper presents a novel Time Division Multiplex Access (TDMA) based Media Access Control (MAC) protocol of wireless Ad Hoc network. To achieve collision free transmission, time slots in a MAC frame are cataloged into three types, that is access slot, control slot and traffic slot. Nodes in the network access to the network in the access slot, and an exclusive control is allocated subsequently. Data packets are transmission by dynamic schedule the traffic slots. Throughput and transmission delay are also analyzed by simulation experiment. The proposed protocol is capable of providing collision free transmission and achieves high throughput.

  15. Pseudo-Coherence-Based MVDR Beamformer for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll;

    2015-01-01

    Speech enhancement with distributed arrays has been met with various methods. On the one hand, data independent methods require information about the position of sensors, so they are not suitable for dynamic geometries. On the other hand, Wiener-based methods cannot assure a distortionless output...... performance criteria are derived in terms of the pseudo-coherence vector, and the method is compared with the multichannel Wiener filter. Evaluation shows the suitability of the proposed method in terms of noise reduction with minimum distortion in ad hoc scenarios....

  16. Trusted Routing Based on Dynamic Trust Mechanism in Mobile Ad-Hoc Networks

    Science.gov (United States)

    Peng, Sancheng; Jia, Weijia; Wang, Guojun; Wu, Jie; Guo, Minyi

    Due to the distributed nature, mobile ad-hoc networks (MANETs) are vulnerable to various attacks, resulting in distrusted communications. To achieve trusted communications, it is important to build trusted routes in routing algorithms in a self-organizing and decentralized fashion. This paper proposes a trusted routing to locate and to preserve trusted routes in MANETs. Instead of using a hard security mechanism, we employ a new dynamic trust mechanism based on multiple constraints and collaborative filtering. The dynamic trust mechanism can effectively evaluate the trust and obtain the precise trust value among nodes, and can also be integrated into existing routing protocols for MANETs, such as ad hoc on-demand distance vector routing (AODV) and dynamic source routing (DSR). As an example, we present a trusted routing protocol, based on dynamic trust mechanism, by extending DSR, in which a node makes a routing decision based on the trust values on its neighboring nodes, and finally, establish a trusted route through the trust values of the nodes along the route in MANETs. The effectiveness of our approach is validated through extensive simulations.

  17. Randomized denoising autoencoders for smaller and efficient imaging based AD clinical trials

    Science.gov (United States)

    Ithapu, Vamsi K.; Singh, Vikas; Okonkwo, Ozioma; Johnson, Sterling C.

    2015-01-01

    There is growing body of research devoted to designing imaging-based biomarkers that identify Alzheimer’s disease (AD) in its prodromal stage using statistical machine learning methods. Recently several authors investigated how clinical trials for AD can be made more efficient (i.e., smaller sample size) using predictive measures from such classification methods. In this paper, we explain why predictive measures given by such SVM type objectives may be less than ideal for use in the setting described above. We give a solution based on a novel deep learning model, randomized denoising autoencoders (rDA), which regresses on training labels y while also accounting for the variance, a property which is very useful for clinical trial design. Our results give strong improvements in sample size estimates over strategies based on multi-kernel learning. Also, rDA predictions appear to more accurately correlate to stages of disease. Separately, our formulation empirically shows how deep architectures can be applied in the large d, small n regime — the default situation in medical imaging. This result is of independent interest. PMID:25485413

  18. Randomized denoising autoencoders for smaller and efficient imaging based AD clinical trials.

    Science.gov (United States)

    Ithapul, Vamsi K; Singh, Vikas; Okonkwo, Ozioma; Johnson, Sterling C

    2014-01-01

    There is growing body of research devoted to designing imaging-based biomarkers that identify Alzheimer's disease (AD) in its prodromal stage using statistical machine learning methods. Recently several authors investigated how clinical trials for AD can be made more efficient (i.e., smaller sample size) using predictive measures from such classification methods. In this paper, we explain why predictive measures given by such SVM type objectives may be less than ideal for use in the setting described above. We give a solution based on a novel deep learning model, randomized denoising autoencoders (rDA), which regresses on training labels y while also accounting for the variance, a property which is very useful for clinical trial design. Our results give strong improvements in sample size estimates over strategies based on multi-kernel learning. Also, rDA predictions appear to more accurately correlate to stages of disease. Separately, our formulation empirically shows how deep architectures can be applied in the large d, small n regime--the default situation in medical imaging. This result is of independent interest.

  19. Gateway Node-Based Greedy Routing Algorithm for Efficient Packet Forwarding in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mohamed Abbas A,

    2011-05-01

    Full Text Available In recent years, vehicular communications are one of the hottest research topics. It has also gained much attention in industry as well as academia. Vehicular Ad Hoc Networks (VANETs are advances of the wireless communication technologies. Routing is one of the key research issues in VANETs as long as it plays an important role in public safety and commercial applications. In VANET, routing of data is a challenging task due to high speed of nodes (i.e., vehicles movement and rapidly changing topology. Recent research showedthat existing routing algorithm solutions for Mobile Ad Hoc Networks (MANETs are not able to meet the unique requirements of vehicular networks. In this paper, we propose Gateway Node-Based Greedy Routing(GNGR, a reliable greedy position-based routing approach algorithm. In GNGR, we forward the packets to any of the nodes in the corner of the transmission range of source/forwarding node as most suitable next hop. With this consideration, the nodes move towards the direction of the destination. We propose Dynamic TransitionMobility Model (DTMM to evaluate our routing technique. This paper gives a complete description of our packet forwarding approach and simulation results. The simulation results are carried out based on Packet Delivery Ratio (PDR. Our routing technique is compared with other routing techniques; the PDR is improved significantly compared with other routing techniques of VANET.

  20. Asymptotic Delay Analysis for Cross-Layer Delay-Based Routing in Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Philippe Jacquet

    2007-01-01

    Full Text Available This paper addresses the problem of the evaluation of the delay distribution via analytical means in IEEE 802.11 wireless ad hoc networks. We show that the asymptotic delay distribution can be expressed as a power law. Based on the latter result, we present a cross-layer delay estimation protocol and we derive new delay-distribution-based routing algorithms, which are well adapted to the QoS requirements of real-time multimedia applications. In fact, multimedia services are not sensitive to average delays, but rather to the asymptotic delay distributions. Indeed, video streaming applications drop frames when they are received beyond a delay threshold, determined by the buffer size. Although delay-distribution-based routing is an NP-hard problem, we show that it can be solved in polynomial time when the delay threshold is large, because of the asymptotic power law distribution of the link delays.

  1. Cooperation in Carrier Sense Based Wireless Ad Hoc Networks - Part I: Reactive Schemes

    CERN Document Server

    Munari, Andrea; Zorzi, Michele

    2012-01-01

    Cooperative techniques have been shown to significantly improve the performance of wireless systems. Despite being a mature technology in single communication link scenarios, their implementation in wider, and practical, networks poses several challenges which have not been fully identified and understood so far. In this two-part paper, the implementation of cooperative communications in non-centralized ad hoc networks with sensing-based channel access is extensively discussed. Both analysis and simulation are employed to provide a clear understanding of the mutual influence between the link layer contention mechanism and collaborative protocols. Part I of this work focuses on reactive cooperation, in which relaying is triggered by packet delivery failure events, while Part II addresses proactive approaches, preemptively initiated by the source based on channel state information. Results show that sensing-based channel access significantly hampers the effectiveness of cooperation by biasing the spatial distri...

  2. French summer droughts since 1326 AD: a reconstruction based on tree ring cellulose δ18O

    Directory of Open Access Journals (Sweden)

    I. Labuhn

    2015-11-01

    Full Text Available The reconstruction of droughts is essential for the understanding of past drought dynamics, and can help evaluate future drought scenarios in a changing climate. This article presents a reconstruction of summer droughts in France based on annually resolved, absolutely dated chronologies of oxygen isotope ratios (δ18O in tree ring cellulose from Quercus spp. Samples were taken from living trees and timber wood from historic buildings at two sites: Fontainebleau (48° 23' N, 2° 40' E; 1326–2000 AD and Angoulême (45° 44' N, 0° 18' E; 1360–2004 AD. Cellulose δ18O from these sites proved to be a good proxy of summer climate, as the trees were sensitive to temperature and moisture availability. However, offsets in average δ18O values between tree cohorts necessitated a correction before joining them to the final chronologies. Using the corrected δ18O chronologies, we developed models based on linear regression to reconstruct drought, expressed by the standardized precipitation evapotranspiration index (SPEI. The significant correlations between the SPEI and cellulose δ18O (r ≈ −0.70, as well as the verification of the models by independent data support the validity of these reconstructions. At both sites, recent decades are characterized by increasing drought. Fontainebleau displays dominantly wetter conditions during earlier centuries, whereas the current drought intensity is not unprecedented in the Angoulême record. While the δ18O chronologies at the two studied sites are highly correlated during the 19th and 20th century, there is a significant decrease in the correlation coefficient between 1550 and 1800 AD, which indicates either a weaker climate sensitivity of the tree ring proxies during this period, or a more heterogeneous climate in the north and the south of France. Future studies of tree ring isotope networks might reveal if the seasonality and spatial patterns of past droughts can explain this decoupling.

  3. French summer droughts since 1326 AD: a reconstruction based on tree ring cellulose δ18O

    Science.gov (United States)

    Labuhn, I.; Daux, V.; Girardclos, O.; Stievenard, M.; Pierre, M.; Masson-Delmotte, V.

    2015-11-01

    The reconstruction of droughts is essential for the understanding of past drought dynamics, and can help evaluate future drought scenarios in a changing climate. This article presents a reconstruction of summer droughts in France based on annually resolved, absolutely dated chronologies of oxygen isotope ratios (δ18O) in tree ring cellulose from Quercus spp. Samples were taken from living trees and timber wood from historic buildings at two sites: Fontainebleau (48° 23' N, 2° 40' E; 1326-2000 AD) and Angoulême (45° 44' N, 0° 18' E; 1360-2004 AD). Cellulose δ18O from these sites proved to be a good proxy of summer climate, as the trees were sensitive to temperature and moisture availability. However, offsets in average δ18O values between tree cohorts necessitated a correction before joining them to the final chronologies. Using the corrected δ18O chronologies, we developed models based on linear regression to reconstruct drought, expressed by the standardized precipitation evapotranspiration index (SPEI). The significant correlations between the SPEI and cellulose δ18O (r ≈ -0.70), as well as the verification of the models by independent data support the validity of these reconstructions. At both sites, recent decades are characterized by increasing drought. Fontainebleau displays dominantly wetter conditions during earlier centuries, whereas the current drought intensity is not unprecedented in the Angoulême record. While the δ18O chronologies at the two studied sites are highly correlated during the 19th and 20th century, there is a significant decrease in the correlation coefficient between 1550 and 1800 AD, which indicates either a weaker climate sensitivity of the tree ring proxies during this period, or a more heterogeneous climate in the north and the south of France. Future studies of tree ring isotope networks might reveal if the seasonality and spatial patterns of past droughts can explain this decoupling.

  4. A HYBRID APPROACH FOR NODE CO-OPERATION BASED CLUSTERING IN MOBILE AD HOC NETWORKS

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    C. Sathiyakumar

    2013-01-01

    Full Text Available A Mobile Ad-Hoc Network (MANET is termed as a set of wireless nodes which could be built with infrastructure less environment where network services are afforded by the nodes themselves. In such a situation, if a node refuses to co-operate with other nodes, then it will lead to a considerable diminution in throughput and the network operation decreases to low optimum value. Mobile Ad hoc Networks (MANETs rely on the collaboration of nodes for packet routing ahead. Nevertheless, much of the existing work in MANETs imagines that mobile nodes (probably possessed by selfish users will pursue prearranged protocols without variation. Therefore, implementing the co-operation between the nodes turn out to be an significant issue. The previous work described a secured key model for ad hoc network with efficient node clustering based on reputation and ranking model. But the downside is that the co-operation with the nodes is less results in a communication error. To enhance the security in MANET, in this work, we present a hybrid approach, build a node co-operation among the nodes in MANET by evaluating the weightage of cooperativeness of each node in MANET. With the estimation of normal co-operative nodes, nodes are restructured on its own (self. Then clustering is made with the reorganized nodes to form a secured communication among the nodes in the MANET environment. The Simulation of the proposed Hybrid Approach for Node Cooperation based Clustering (HANCC work is done for varying topology, node size, attack type and intensity with different pause time settings and the performance evaluations are carried over in terms of node cooperativeness, clustering efficiency, communication overhead and compared with an existing secured key model. Compared to an existing secured key model, the proposed HANCC performance is 80-90% high.

  5. Intelligent Networks Data Fusion Web-based Services for Ad-hoc Integrated WSNs-RFID

    Directory of Open Access Journals (Sweden)

    Falah Alshahrany

    2016-01-01

    Full Text Available The use of variety of data fusion tools and techniques for big data processing poses the problem of the data and information integration called data fusion having objectives which can differ from one application to another. The design of network data fusion systems aimed at meeting these objectives, need to take into account of the necessary synergy that can result from distributed data processing within the data networks and data centres, involving increased computation and communication. This papers reports on how this processing distribution is functionally structured as configurable integrated web-based support services, in the context of an ad-hoc wireless sensor network used for sensing and tracking, in the context of distributed detection based on complete observations to support real rime decision making. The interrelated functional and hardware RFID-WSN integration is an essential aspect of the data fusion framework that focuses on multi-sensor collaboration as an innovative approach to extend the heterogeneity of the devices and sensor nodes of ad-hoc networks generating a huge amount of heterogeneous soft and hard raw data. The deployment and configuration of these networks require data fusion processing that includes network and service management and enhances the performance and reliability of networks data fusion support systems providing intelligent capabilities for real-time control access and fire detection.

  6. Developing an Accelerator Driven System (ADS) based on electron accelerators and heavy water

    Science.gov (United States)

    Feizi, H.; Ranjbar, A. H.

    2016-02-01

    An ADS based on electron accelerators has been developed specifically for energy generation and medical applications. Monte Carlo simulations have been performed using FLUKA code to design a hybrid electron target and the core components. The composition, geometry of conversion targets and the coolant system have been optimized for electron beam energies of 20 to 100 MeV . Furthermore, the photon and photoneutron energy spectra, distribution and energy deposition for various incoming electron beam powers have been studied. Light-heavy water of various mixtures have been used as heat removal for the targets, as γ-n converters and as neutron moderators. We have shown that an electron LINAC, as a neutron production driver for ADSs, is capable of producing a neutron output of > 3.5 × 1014 (n/s/mA). Accordingly, the feasibility of an electron-based ADS employing the designed features is promising for energy generation and high intense neutron production which have various applications such as medical therapies.

  7. 基于遗传算法的Ad hoc路由协议优化%Routing Protocol Optimization for Ad hoc Networks Based on Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    詹思瑜; 李建平

    2012-01-01

    目前存在大量的Ad hoc网络路由协议,但是很少有研究对这些协议的最优性能进行过分析.通过对Ad hoc网络路由协议的分析,结合遗传算法的基本原理,对路由协议参数的全局优化配置提出一种启发式求解算法.该算法采用可变长编码,结合遗传算法的选择、交叉和变异操作,对路由协议的性能进行全局优化.在NS2平台上的仿真试验结果表明,优化后的路由协议性能比未优化之前提高30%.%A huge number of routing protocols have been proposed but few researches of the optimal performance of these protocols have been done. In this paper, the performance of Ad hoc networks routing protocols was studied and a novel algorithm was proposed to do a global optimization for routing protocols parameters setting based on genetic algorithm. The presented algorithm adopted variable-length chromosomes encoding, applied selection, crossover and mutation to optimize the routing protocols performance of Ad hoc networks. As shown in our simulations implemented on ns2, the performance of optimized routing protocols can be improved more than 30%.

  8. Research Of A Intelligent Transport Model Based on Ad Hoc Network%基于Ad Hoc网络的智能交通模型研究

    Institute of Scientific and Technical Information of China (English)

    刘钢; 郭晗

    2012-01-01

    目前,我国多数大中型城市的交通拥堵问题都很严重.若能够合理的分配道路资源、动态获得拥堵路段和准拥堵路段的交通信息,辅助司机做出正确判断,避开车流拥堵的储段,可以从根本上做到缓解整个交通拥堵的目的.本文所讨论的就是建立一个AdHoe网为基础的智能交通模型,车辆可以实时从AdHoe网当中获得交通信息,提前感知到交通拥堵将出现在哪条街道上,并做出合理判断和选择.%On present, our most large and medium - size cities were in very serious trouble of traffic jams. If we can distribute the road resource reasonably, gathering the traffic information of congestion roads and the quasi - congestion road dynamically, that can assist the drivers to make the right judgments. Thus the drivers can avoid the congestion roads and achieve the purpose of ease the traffic congestion fundamentally. What be discussed in this paper is to establish an intelligent model of traffic based on Ad Hoc network. Vehicles can obtained the road information in the Ad Hoc network timely and make right judgment and decisions.

  9. Assessing State Models of Value-Added Teacher Evaluations: Alignment of Policy, Instruments, and Literature-Based Concepts

    Science.gov (United States)

    Hadfield, Timothy E.; Hutchison-Lupardus, Tammy R.; Snyder, Jennifer E.

    2012-01-01

    This problem-based learning project addressed the need to improve the construction and implementation of value-added teacher evaluation policies and instruments. State officials are constructing value-added teacher evaluation models due to accountability initiatives, while ignoring the holes and problems in its implementation. The team's…

  10. Trilateration-based localization algorithm for ADS-B radar systems

    Science.gov (United States)

    Huang, Ming-Shih

    Rapidly increasing growth and demand in various unmanned aerial vehicles (UAV) have pushed governmental regulation development and numerous technology research advances toward integrating unmanned and manned aircraft into the same civil airspace. Safety of other airspace users is the primary concern; thus, with the introduction of UAV into the National Airspace System (NAS), a key issue to overcome is the risk of a collision with manned aircraft. The challenge of UAV integration is global. As automatic dependent surveillance-broadcast (ADS-B) system has gained wide acceptance, additional exploitations of the radioed satellite-based information are topics of current interest. One such opportunity includes the augmentation of the communication ADS-B signal with a random bi-phase modulation for concurrent use as a radar signal for detecting other aircraft in the vicinity. This dissertation provides detailed discussion about the ADS-B radar system, as well as the formulation and analysis of a suitable non-cooperative multi-target tracking method for the ADS-B radar system using radar ranging techniques and particle filter algorithms. In order to deal with specific challenges faced by the ADS-B radar system, several estimation algorithms are studied. Trilateration-based localization algorithms are proposed due to their easy implementation and their ability to work with coherent signal sources. The centroid of three most closely spaced intersections of constant-range loci is conventionally used as trilateration estimate without rigorous justification. In this dissertation, we address the quality of trilateration intersections through range scaling factors. A number of well-known triangle centers, including centroid, incenter, Lemoine point (LP), and Fermat point (FP), are discussed in detail. To the author's best knowledge, LP was never associated with trilateration techniques. According our study, LP is proposed as the best trilateration estimator thanks to the

  11. Mitigating Malicious Attacks Using Trust Based Secure-BEFORE Routing Strategy in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rutuja Shah

    2016-09-01

    Full Text Available Mobile ad hoc Networks (MANET, being infrastructureless and dynamic in nature, are predominantly susceptible to attacks such as black hole, worm hole, cunning gray hole attack at source or destination. Various solutions have been put forth so far in literature in order to mitigate the effects of these attacks on the network performance and to improve the reliability of the network. However, these attacks are still prominently a serious threat in MANET. Hence, a trust based routing strategy termed Secure-BEFORE routing (Best FOrwarding Route Estimation is proposed to ensure optimal route estimation in computing the trust value and hop counts using the dummy packets inside the network at 1-hop level. It is observed that the overall performance of the network is improved in providing one-hop level security by maintaining the packet equivalence ratio. Malicious and suspicious nodes are isolated and eliminated from the network, based on their behavior.

  12. POWER-AWARE ROUTING BASED ON DSR FOR MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Huang Jingbo; Hong Peilin; Li Jinsheng

    2007-01-01

    Energy consumption is a crucial design concern in Mobile Ad hoc NETworks (MANETs)since nodes are powered by batteries with limited energy, whereas Dynamic Source Routing (DSR)protocol does not take the energy limitation of MANET nodes into account. This paper proposes an energy-saving routing algorithm based on DSR: Power Aware Routing protocol based on DSR (PAR-DSR). The design objective of PAR-DSR is to select energy-efficient paths. The main features of PAR-DSR are: (1) Nodes use the Signal Attenuation Rate (SAR) to conduct power control operations;(2) Minimum path cost as metric to balance the traffic and energy consumption of wireless nodes. The simulation results show that PAR-DSR can greatly reduce the energy consumption of MANET nodes.The average node lifetime of PAR-DSR is 50%-77% longer than that of DSR.

  13. Location-based route self-recovery for mobile ad hoc networks

    Science.gov (United States)

    Medidi, Sirisha; Wang, Jiong

    2007-04-01

    Mobile ad hoc network (MANET) is a radio packet network without dedicated infrastructures. In recent years it has received tremendous attention because of its self-configuration and self-maintenance capabilities. However, because of node mobility and shared wireless links, its routing protocol design presents nontrivial challenges such as broadcast storm, stale route and delay. This paper proposes a location-based route self-recovery technique for source-initiated routing protocols. The purpose of route self-recovery is to reduce overhead and delay during route maintenance as well as allowing continuous packet forwarding for fault resilience. The ns-2 based simulation shows throughput and overhead improvements of source-initiated routing with route self-recovery and in the case of highly dynamic environments and heavy traffic loads, it is more robust and scalable than other protocols.

  14. A Protocol for Content-Based Communication in Disconnected Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Julien Haillot

    2010-01-01

    Full Text Available In content-based communication, information flows towards interested hosts rather than towards specifically set destinations. This new style of communication perfectly fits the needs of applications dedicated to information sharing, news distribution, service advertisement and discovery, etc. In this paper we address the problem of supporting content-based communication in partially or intermittently connected mobile ad hoc networks (MANETs. The protocol we designed leverages on the concepts of opportunistic networking and delay-tolerant networking in order to account for the absence of end-to-end connectivity in disconnected MANETs. The paper provides an overview of the protocol, as well as simulation results that show how this protocol can perform in realistic conditions.

  15. A Cluster Maintenance Algorithm Based on Relative Mobility for Mobile Ad Hoc Network Management

    Institute of Scientific and Technical Information of China (English)

    SHENZhong; CHANGYilin; ZHANGXin

    2005-01-01

    The dynamic topology of mobile ad hoc networks makes network management significantly more challenging than wireline networks. The traditional Client/Server (Manager/Agent) management paradigm could not work well in such a dynamic environment, while the hierarchical network management architecture based on clustering is more feasible. Although the movement of nodes makes the cluster structure changeable and introduces new challenges for network management, the mobility is a relative concept. A node with high relative mobility is more prone to unstable behavior than a node with less relative mobility, thus the relative mobility of a node can be used to predict future node behavior. This paper presents the cluster availability which provides a quantitative measurement of cluster stability. Furthermore, a cluster maintenance algorithm based on cluster availability is proposed. The simulation results show that, compared to the Minimum ID clustering algorithm, our algorithm successfully alleviates the influence caused by node mobility and make the network management more efficient.

  16. Adding memory processing behaviors to the fuzzy behaviorist-based navigation of mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Pin, F.G.; Bender, S.R.

    1996-05-01

    Most fuzzy logic-based reasoning schemes developed for robot control are fully reactive, i.e., the reasoning modules consist of fuzzy rule bases that represent direct mappings from the stimuli provided by the perception systems to the responses implemented by the motion controllers. Due to their totally reactive nature, such reasoning systems can encounter problems such as infinite loops and limit cycles. In this paper, we proposed an approach to remedy these problems by adding a memory and memory-related behaviors to basic reactive systems. Three major types of memory behaviors are addressed: memory creation, memory management, and memory utilization. These are first presented, and examples of their implementation for the recognition of limit cycles during the navigation of an autonomous robot in a priori unknown environments are then discussed.

  17. Dynamic autonomous routing technology for IP-based satellite ad hoc networks

    Science.gov (United States)

    Wang, Xiaofei; Deng, Jing; Kostas, Theresa; Rajappan, Gowri

    2014-06-01

    IP-based routing for military LEO/MEO satellite ad hoc networks is very challenging due to network and traffic heterogeneity, network topology and traffic dynamics. In this paper, we describe a traffic priority-aware routing scheme for such networks, namely Dynamic Autonomous Routing Technology (DART) for satellite ad hoc networks. DART has a cross-layer design, and conducts routing and resource reservation concurrently for optimal performance in the fluid but predictable satellite ad hoc networks. DART ensures end-to-end data delivery with QoS assurances by only choosing routing paths that have sufficient resources, supporting different packet priority levels. In order to do so, DART incorporates several resource management and innovative routing mechanisms, which dynamically adapt to best fit the prevailing conditions. In particular, DART integrates a resource reservation mechanism to reserve network bandwidth resources; a proactive routing mechanism to set up non-overlapping spanning trees to segregate high priority traffic flows from lower priority flows so that the high priority flows do not face contention from low priority flows; a reactive routing mechanism to arbitrate resources between various traffic priorities when needed; a predictive routing mechanism to set up routes for scheduled missions and for anticipated topology changes for QoS assurance. We present simulation results showing the performance of DART. We have conducted these simulations using the Iridium constellation and trajectories as well as realistic military communications scenarios. The simulation results demonstrate DART's ability to discriminate between high-priority and low-priority traffic flows and ensure disparate QoS requirements of these traffic flows.

  18. Strategies for adding adaptive learning mechanisms to rule-based diagnostic expert systems

    Science.gov (United States)

    Stclair, D. C.; Sabharwal, C. L.; Bond, W. E.; Hacke, Keith

    1988-01-01

    Rule-based diagnostic expert systems can be used to perform many of the diagnostic chores necessary in today's complex space systems. These expert systems typically take a set of symptoms as input and produce diagnostic advice as output. The primary objective of such expert systems is to provide accurate and comprehensive advice which can be used to help return the space system in question to nominal operation. The development and maintenance of diagnostic expert systems is time and labor intensive since the services of both knowledge engineer(s) and domain expert(s) are required. The use of adaptive learning mechanisms to increment evaluate and refine rules promises to reduce both time and labor costs associated with such systems. This paper describes the basic adaptive learning mechanisms of strengthening, weakening, generalization, discrimination, and discovery. Next basic strategies are discussed for adding these learning mechanisms to rule-based diagnostic expert systems. These strategies support the incremental evaluation and refinement of rules in the knowledge base by comparing the set of advice given by the expert system (A) with the correct diagnosis (C). Techniques are described for selecting those rules in the in the knowledge base which should participate in adaptive learning. The strategies presented may be used with a wide variety of learning algorithms. Further, these strategies are applicable to a large number of rule-based diagnostic expert systems. They may be used to provide either immediate or deferred updating of the knowledge base.

  19. A communication theoretical analysis of FRET-based mobile ad hoc molecular nanonetworks.

    Science.gov (United States)

    Kuscu, Murat; Akan, Ozgur B

    2014-09-01

    Nanonetworks refer to a group of nanosized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Förster Resonance Energy Transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, for the first time in the literature, we investigate the network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation based on birth-death processes with continuous time Markov chains. We evaluate the performance of FRET-MSAN and FRET-MAMNET in terms of successful transmission probability and mean extinction time of the messages, system throughput, channel capacity and achievable communication rates.

  20. The taxable events for the Value-Added Tax (VAT based on a Comparative Law approach

    Directory of Open Access Journals (Sweden)

    Walker Villanueva Gutiérrez

    2014-07-01

    Full Text Available This article analyzes the definitions of the main taxable events for the Value-Added Tax (VAT based on a comparative approach to thelegislation of different countries (Spain, Mexico, Chile, Colombia, Argentina and Peru. In this regard, it analyzes which legislations offer definitions according to the principles of generality, fiscal neutrality and legal certainty for VAT. Moreover, it points out that the VAT systems of those countries do not require as a condition for the configuration of the taxable events that the transactions involve a «value added» or a final consumption. In the specificcase of «supplies of goods», the VAT systems have a similar definition of the taxable event, although there are a few differences. However, in the case of«supplies of services», which is the most important taxable event for VAT, there are important differences at the time each country defines it. This is not a desirable effect for the international trade of services, since the lack of harmonization produces double taxation or double non taxation.

  1. Intelligent QoS routing algorithm based on improved AODV protocol for Ad Hoc networks

    Science.gov (United States)

    Huibin, Liu; Jun, Zhang

    2016-04-01

    Mobile Ad Hoc Networks were playing an increasingly important part in disaster reliefs, military battlefields and scientific explorations. However, networks routing difficulties are more and more outstanding due to inherent structures. This paper proposed an improved cuckoo searching-based Ad hoc On-Demand Distance Vector Routing protocol (CSAODV). It elaborately designs the calculation methods of optimal routing algorithm used by protocol and transmission mechanism of communication-package. In calculation of optimal routing algorithm by CS Algorithm, by increasing QoS constraint, the found optimal routing algorithm can conform to the requirements of specified bandwidth and time delay, and a certain balance can be obtained among computation spending, bandwidth and time delay. Take advantage of NS2 simulation software to take performance test on protocol in three circumstances and validate the feasibility and validity of CSAODV protocol. In results, CSAODV routing protocol is more adapt to the change of network topological structure than AODV protocol, which improves package delivery fraction of protocol effectively, reduce the transmission time delay of network, reduce the extra burden to network brought by controlling information, and improve the routing efficiency of network.

  2. Low Power 24 GHz ad hoc Networking System Based on TDOA for Indoor Localization

    Directory of Open Access Journals (Sweden)

    Melanie Jung

    2013-12-01

    Full Text Available This paper introduces the key elements of a novel low-power, high precision localization system based on Time-Difference-of-Arrival (TDOA distance measurements. The combination of multiple localizable sensor nodes, leads to an ad hoc network. Besides the localization functionality this ad hoc network has the additional advantage of a communication interface. Due to this a flexible positioning of the master station for information collection and the detection of static and mobile nodes is possible. These sensor nodes work in the 24 GHz ISM (Industrial Scientific and Medical frequency range and address several use cases and are able to improve various processes for production scheduling, logistics, quality management, medical applications and collection of geo information. The whole system design is explained briefly. Its core component is the frequency modulated continuous wave (FMCW synthesizer suitable for high performance indoor localization. This research work focuses on power and size reduction of this crucial system component. The comparison of the first and second generation of the system shows a significant size and power reduction as well as an increased precision.

  3. DRMR:Dynamic-Ring-Based Multicast Routing Protocol for Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhoux; Guang-Sheng Li; Yong-Zhao Zhan; Qi-Rong Mao; Yi-Bin Hou

    2004-01-01

    Recently a number of multicast routing protocols for ad hoc networks have been proposed, however, most of them do not provide proper tradeoffs between effectiveness, efficiency and scalability. In this paper, a novel multicast routing protocol is presented for ad hoc networks. The protocol, termed as dynamic-ring-based multicast routing protocol (DRMR), uses the concept of dynamic ring whose radius can be adjusted dynamically and DRMR configures this type of ring for all group member nodes. According to the principle of zone routing, two nodes whose rings overlap can create route to each other, thus, when the ring graph composed of all rings is connected, each member node has one or more routes to others. DRMR uses the method of expanding ring search (ERS) to maintain the connected ring graph, and also can decrease the radius of the ring to reduce the overhead. The performances of DRMR were simulated and evaluated with NS2, and results show that DRMR has a high data packet delivery ratio, low control overhead and good scalability.

  4. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks.

    Science.gov (United States)

    Robinson, Y Harold; Rajaram, M

    2015-01-01

    Mobile ad hoc network (MANET) is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO) that uses continuous time recurrent neural network (CTRNN) to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO) method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique.

  5. HIERARCHICAL DESIGN BASED INTRUSION DETECTION SYSTEM FOR WIRELESS AD HOC SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    Mohammad Saiful Islam Mamun

    2010-07-01

    Full Text Available In recent years, wireless ad hoc sensor network becomes popular both in civil and military jobs.However, security is one of the significant challenges for sensor network because of their deploymentin open and unprotected environment. As cryptographic mechanism is not enough to protect sensornetwork from external attacks, intrusion detection system needs to be introduced. Though intrusionprevention mechanism is one of the major and efficient methods against attacks, but there might besome attacks for which prevention method is not known. Besides preventing the system from someknown attacks, intrusion detection system gather necessary information related to attack technique andhelp in the development of intrusion prevention system. In addition to reviewing the present attacksavailable in wireless sensor network this paper examines the current efforts to intrusion detectionsystem against wireless sensor network. In this paper we propose a hierarchical architectural designbased intrusion detection system that fits the current demands and restrictions of wireless ad hocsensor network. In this proposed intrusion detection system architecture we followed clusteringmechanism to build a four level hierarchical network which enhances network scalability to largegeographical area and use both anomaly and misuse detection techniques for intrusion detection. Weintroduce policy based detection mechanism as well as intrusion response together with GSM cellconcept for intrusion detection architecture.

  6. Self-Organized Hash Based Secure Multicast Routing Over Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Amit Chopra

    2016-02-01

    Full Text Available Multicast group communication over mobile ad hoc networks has various challenges related to secure data transmission. In order to achieve this goal, there is a need to authenticate the group member as well as it is essential to protect the application data, routing information, and other network resources etc. Multicast-AODV (MAODV is the extension of an AODV protocol, and there are several issues related to each multicast network operation. In the case of dynamic group behavior, it becomes more challenging to protect the resources of a particular group. Researchers have developed different solutions to secure multicast group communication, and their proposed solutions can be used for resource protection at different layers i.e. application layer, physical layer, network layer, etc. Each security solution can guard against a particular security threat. This research paper introduced a self-organized hash based secure routing scheme for multicast ad hoc networks. It uses group Diffie-Hellman method for key distribution. Route authentication and integrity, both are ensured by generating local flag codes and global hash values. In the case of any violation, route log is monitored to identify the malicious activities.

  7. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Y. Harold Robinson

    2015-01-01

    Full Text Available Mobile ad hoc network (MANET is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO that uses continuous time recurrent neural network (CTRNN to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique.

  8. Access control based on clustering in Ad Hoc networks%Ad Hoc网络中基于分簇的访问控制方案

    Institute of Scientific and Technical Information of China (English)

    程帆; 王晓明

    2012-01-01

    This paper proposes an access control scheme for cluster-based Ad Hoc networks. This scheme classifies the resources and nodes into levels to provide differentiated privileges access control. A dynamic access control mechanism is implemented based on the simple effective trust model and incentive mechanism which can change the node' s privilege. The cluster-head proxy is developed to access the resource that enhances security and fully utilizes the quality resources. Simulations result show that this scheme is of high efficiency and little communication.%基于分簇结构提出一种适用于Ad Hoc网络的访问控制方案.通过将资源和节点分等级来实现不同权限的访问控制;采用简单有效的信誉模型和激励机制来改变节点的权限,实现了动态的访问控制;通过簇头代理访问资源,增强了网络的安全性,并且使网络中优质资源得到充分利用.仿真结果表明,该方案有较高的效率和较少的通信量.

  9. Beam-based calibrations of the BPM offset at C-ADS Injector II

    Science.gov (United States)

    Chen, Wei-Long; Wang, Zhi-Jun; Feng, Chi; Dou, Wei-Ping; Tao, Yue; Jia, Huan; Wang, Wang-Sheng; Liu, Shu-Hui; He, Yuan

    2016-07-01

    Beam-based BPM offset calibration was carried out for Injector II at the C-ADS demonstration facility at the Institute of Modern Physics (IMP), Chinese Academy of Science (CAS). By using the steering coils integrated in the quadrupoles, the beam orbit can be effectively adjusted and BPM positions recorded at the Medium Energy Beam Transport of the Injector II Linac. The studies were done with a 2 mA, 2.1 MeV proton beam in pulsed mode. During the studies, the “null comparison method” was applied for the calibration. This method is less sensitive to errors compared with the traditional transmission matrix method. In addition, the quadrupole magnet’s center can also be calibrated with this method. Supported by National Natural Science Foundation of China (91426303, 11525523)

  10. PCBA: A Priority-Based Competitive Broadcasting Algorithm in Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    ZHOU BoSheng(周伯生); WU JieYi(吴介一); FEI Xiang(费翔); ZHAO Jian(赵键)

    2003-01-01

    Broadcasting operations are of great importance in Mobile Ad Hoc Networks(MANETs) since they are frequently executed. A straightforward broadcasting by flooding willproduce serious redundancy, contention and collision, and furthermore it will result in the perfor-mance degradation of the networks. PCBA, a Priority-based Competitive Broadcasting Algorithm,is proposed in this paper to solve the above problem. In this algorithm, hosts with larger PriorityIndex (PI) have higher probability to rebroadcast relevant messages while some other hosts will beprevented from rebroadcasting according to the competing policy. PCBA is a distributed algorithmand will not increase communication overhead. Through the analyses and extensive simulations,the authors demonstrate that PCBA has advantages in availability and scalability. It can signif-icantly reduce the rebroadcast redundancy. In addition, PCBA can also be further used in otherapplications such as routing discovery schemes, enhancing the performance.

  11. Cooperative Reputation Index Based Selfish Node Detection and Prevention System for Mobile Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    Muhammad Arsalan Paracha

    2012-04-01

    Full Text Available In Ad hoc networks every node plays an important part in the transmission of packets from sender to receiver. Most of the time packet delivery ratio of these networks depends on the behavior of intermediate nodes. Sometimes these intermediate nodes cooperate and forward the packets of their neighbor and some time they simply drop their packets and cheat their neighbors. We present a solution that not only detect these selfish nodes but also punish these nodes so that they avoid such misbehavior in future. To this account, we use an agent “Neighbor Monitor”, running on every node, to monitor the traffic of neighbors and assign a value called “Reputation Index”, associated with each node, based on its behavior.

  12. Trust Based Scheme for QoS Assurance in Mobile Ad-Hoc Networks

    CERN Document Server

    Subramanian, Sridhar

    2012-01-01

    A mobile ad-hoc network (MANET) is a peer-to-peer wireless network where nodes can communicate with each other without the use of infrastructure such as access points or base stations. These networks are self-configuring, capable of self-directed operation and hastily deployable. Nodes cooperate to provide connectivity, operates without centralized administration. Nodes are itinerant, topology can be very dynamic and nodes must be able to relay traffic since communicating nodes might be out of range. The dynamic nature of MANET makes network open to attacks and unreliability. Routing is always the most significant part for any networks. Each node should not only work for itself, but should be cooperative with other nodes. Node misbehaviour due to selfish or malicious intention could significantly degrade the performance of MANET. The Qos parameters like PDR, throughput and delay are affected directly due to such misbehaving nodes. We focus on trust management framework, which is intended to cope with misbehav...

  13. Key Management and Authentication in Ad Hoc Network based on Mobile Agent

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2009-08-01

    Full Text Available Key management and authentication is important to security of Mobile Ad Hoc network (MANET. Based on the (t, n threshold cryptography, this paper introduced mobile agents to exchange private key and network topological information with nodes in the network. This method avoids a centralized certification authority to distribute the public keys and the certificates, thus enhances security. Carrying private key and some state variables, mobile agents navigate in the network according to visitsbalance policy, namely, node with the least visits would be first visited by mobile agent. Any t nodes in the network can cooperate to perform an authentication upon a new node wanting to join the network. Experimental results show that the mobile agent performs very well for improving the success ratio of authentication and enhance security while reducing the communication overhead and resource consumption.

  14. Ants-Based On-Demand Routing Algorithm for Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    An ants-based on-demand routing algorithm (AORA) specialized for mobile ad hoc networks is proposed. AORA measures the network's traffic information including delivery time,route energy etc. by the continuous delivery of data packets,then calculates the compositive parameter for each route which can be seen as the stigmity and uses it to choose the comparatively optimal route in real time.To adjust the weight of each traffic information,the algorithm can meet the different demand of the network's user. Multipath source self repair routing (MSSRR) algorithm and dynamic source routing (DSR) can be seen as the special samples of AORA. The routing overhead is not increased in this algorithm. By using simulation, it can be seen that the performance of AORA is better than that of DSR in all scenarios obviously,especially the delivery fraction is increased by more than 100%.

  15. Link reliability based hybrid routing for tactical mobile ad hoc network

    Institute of Scientific and Technical Information of China (English)

    Xie Xiaochuan; Wei Gang; Wu Keping; Wang Gang; Jia Shilou

    2008-01-01

    Tactical mobile ad hoc network (MANET) is a collection of mobile nodes forming a temporary network,without the aid of pre-established network infrastructure. The routing protocol has a crucial impact on the networkperformance in battlefields. Link reliability based hybrid routing (LRHR) is proposed, which is a novel hybrid routing protocol, for tactical MANET. Contrary to the traditional single path routing strategy, multiple paths are established between a pair of source-destination nodes. In the hybrid routing strategy, the rate of topological change provides a natural mechanism for switching dynamically between table-driven and on-demand routing. The simulation results indicate that the performances of the protocol in packet delivery ratio, routing overhead, and average end-to-end delay are better than the conventional routing protocol.

  16. A Multi-Channel Diversity Based MAC Protocol for Power-Constrained Cognitive Ad Hoc Networks

    CERN Document Server

    Wang, Yichen; Du, Qinghe; Zhang, Chao

    2011-01-01

    One of the major challenges in the medium access control (MAC) protocol design over cognitive Ad Hoc networks (CAHNs) is how to efficiently utilize multiple opportunistic channels, which vary dynamically and are subject to limited power resources. To overcome this challenge, in this paper we first propose a novel diversity technology called \\emph{Multi-Channel Diversity} (MCD), allowing each secondary node to use multiple channels simultaneously with only one radio per node under the upperbounded power. Using the proposed MCD, we develop a MCD based MAC (MCD-MAC) protocol, which can efficiently utilize available channel resources through joint power-channel allocation. Particularly, we convert the joint power-channel allocation to the Multiple-Choice Knapsack Problem, such that we can obtain the optimal transmission strategy to maximize the network throughput through dynamic programming. Simulation results show that our proposed MCD-MAC protocol can significantly increase the network throughput as compared to...

  17. A New Cluster-based Wormhole Intrusion detection algorithm for Mobile Ad-Hoc Networks

    CERN Document Server

    Roy, Debdutta Barman; Chaki, Nabendu

    2010-01-01

    In multi-hop wireless systems, the need for cooperation among nodes to relay each other's packets exposes them to a wide range of security attacks. A particularly devastating attack is the wormhole attack, where a malicious node records control traffic at one location and tunnels it to another compromised node, possibly far away, which replays it locally. Routing security in ad hoc networks is often equated with strong and feasible node authentication and lightweight cryptography. Unfortunately, the wormhole attack can hardly be defeated by crypto graphical measures, as wormhole attackers do not create separate packets. They simply replay packets already existing on the network, which pass the cryptographic checks. Existing works on wormhole detection have often focused on detection using specialized hardware, such as directional antennas, etc. In this paper, we present a cluster based counter-measure for the wormhole attack, that alleviates these drawbacks and efficiently mitigates the wormhole attack in MAN...

  18. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks.

    Science.gov (United States)

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-07-14

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes.

  19. AN IMMUNITY-BASED SECURITY ARCHITECTURE FOR MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper focuses on investigating immunological principles in designing a multi-agent security architecture for intrusion detection and response in mobile ad hoc networks. In this approach, the immunity-based agents monitor the situation in the network. These agents can take appropriate actions according to the underlying security policies. Specifically, their activities are coordinated in a hierarchical fashion while sensing,communicating, decision and generating responses. Such an agent can learn and adapt to its environment dynamically and can detect both known and unknown intrusions. The proposed intrusion detection architecture is designed to be flexible, extendible, and adaptable that can perform real-time monitoring. This paper provides the conceptual view and a general framework of the proposed system. In the end, the architecture is illustrated by an example to show it can prevent the attack efficiently.

  20. Securing mobile ad hoc networks using danger theory-based artificial immune algorithm.

    Directory of Open Access Journals (Sweden)

    Maha Abdelhaq

    Full Text Available A mobile ad hoc network (MANET is a set of mobile, decentralized, and self-organizing nodes that are used in special cases, such as in the military. MANET properties render the environment of this network vulnerable to different types of attacks, including black hole, wormhole and flooding-based attacks. Flooding-based attacks are one of the most dangerous attacks that aim to consume all network resources and thus paralyze the functionality of the whole network. Therefore, the objective of this paper is to investigate the capability of a danger theory-based artificial immune algorithm called the mobile dendritic cell algorithm (MDCA to detect flooding-based attacks in MANETs. The MDCA applies the dendritic cell algorithm (DCA to secure the MANET with additional improvements. The MDCA is tested and validated using Qualnet v7.1 simulation tool. This work also introduces a new simulation module for a flooding attack called the resource consumption attack (RCA using Qualnet v7.1. The results highlight the high efficiency of the MDCA in detecting RCAs in MANETs.

  1. Selective Route Based on SNR with Cross-Layer Scheme in Wireless Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Istikmal

    2017-01-01

    Full Text Available In this study, we developed network and throughput formulation models and proposed new method of the routing protocol algorithm with a cross-layer scheme based on signal-to-noise ratio (SNR. This method is an enhancement of routing protocol ad hoc on-demand distance vector (AODV. This proposed scheme uses selective route based on the SNR threshold in the reverse route mechanism. We developed AODV SNR-selective route (AODV SNR-SR for a mechanism better than AODV SNR, that is, the routing protocol that used average or sum of path SNR, and also better than AODV which is hop-count-based. We also used selective reverse route based on SNR mechanism, replacing the earlier method to avoid routing overhead. The simulation results show that AODV SNR-SR outperforms AODV SNR and AODV in terms of throughput, end-to-end delay, and routing overhead. This proposed method is expected to support Device-to-Device (D2D communications that are concerned with the quality of the channel awareness in the development of the future Fifth Generation (5G.

  2. Securing mobile ad hoc networks using danger theory-based artificial immune algorithm.

    Science.gov (United States)

    Abdelhaq, Maha; Alsaqour, Raed; Abdelhaq, Shawkat

    2015-01-01

    A mobile ad hoc network (MANET) is a set of mobile, decentralized, and self-organizing nodes that are used in special cases, such as in the military. MANET properties render the environment of this network vulnerable to different types of attacks, including black hole, wormhole and flooding-based attacks. Flooding-based attacks are one of the most dangerous attacks that aim to consume all network resources and thus paralyze the functionality of the whole network. Therefore, the objective of this paper is to investigate the capability of a danger theory-based artificial immune algorithm called the mobile dendritic cell algorithm (MDCA) to detect flooding-based attacks in MANETs. The MDCA applies the dendritic cell algorithm (DCA) to secure the MANET with additional improvements. The MDCA is tested and validated using Qualnet v7.1 simulation tool. This work also introduces a new simulation module for a flooding attack called the resource consumption attack (RCA) using Qualnet v7.1. The results highlight the high efficiency of the MDCA in detecting RCAs in MANETs.

  3. A Policy Based Scheme for Combined Data Security in Mobile Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    S. K. Srivatsa

    2012-01-01

    Full Text Available Problem statement: In Mobile Ad hoc Networks (MANET routing protocols, we require a network-level or link layer security. Since without appropriate security provisions, the MANETs is subjected to attacks like network traffic, replay transmissions, manipulate packet headers and redirect routing messages. In order to address these needs, a policy based network management system that provides the capability to express network requirements is required. Approach: In this study, we propose a policy based scheme for combined data security which focuses mainly on three policies: Integrity, authentication and Confidentiality. For providing security not only to data, but also for routing information, we calculate the trust indexes of the nodes and the route is selected according to the trust value which improves integrity. Then in order to provide authentication, we propose a Distributed Certificate Authority (DCA technique in which multiple DCA is required to construct a certificate. Next we propose an RSA based novel encryption mechanism in order to provide Confidentiality among the nodes. Thus, the desired level of security is provided by the system based on the policy of the user by executing the corresponding security modules. Results: By simulation results, we show that this scheme provides a combined data security in MANETs and can be used efficiently. Conclusion: Our proposed combined data security policy provides complete protection for the data in MANET communications.

  4. ON DHT-BASED ROUTING FOR MOBILE AD HOC NETWORKS%基于DHT的移动Ad hoc路由研究

    Institute of Scientific and Technical Information of China (English)

    刘峰; 张振宇; 张琳琳; 赵静

    2011-01-01

    The application of distributed hash tables (DHTs) s trengthens the scalability of P2P networks. How to transplant it to MANET has attracted extensive concerns. As MANET has the characteristics of resource limitation and high dynamic property, in light of these, in this paper a new routing model for MANET based on DHTs is proposed. In this model the topology consistence of distributed hash tables is enhanced by setting virtual coordinates, and the link stability is improved by the prediction mechanism of link' s lifetime. The results of simulation show that the two key indices,average physical hops and packet delivery ratio,are all improved a great deal.%分布式哈希表的应用增强了P2P网络的可扩展性,如何将其移植到移动Ad hoc网络受到了广泛关注.针对移动Ad hoc网络资源受限和高度动态性的特点,提出了一种基于分布式哈希表的移动Ad hoc路由模型,该模型通过设置虚拟坐标点来增强分布式哈希表的拓扑一致性,通过链路生存时间预测机制来增强路由链路的稳定性.仿真实验结果表明,该模型在平均物理跳数和分组投递率两个关键指标有了较大提高.

  5. 基于链路质量的移动Ad hoc路由算法%Routing Algorithm Based on Link Quality in Moblie Ad hoc Networks

    Institute of Scientific and Technical Information of China (English)

    曾格平; 陈越

    2013-01-01

    针对在移动Ad hoc网络中,由于节点移动和能量有限导致节点失效、传输链路不稳定的问题,改进原有链路剩余时间计算方法,并与节点剩余能量结合计算路径质量,将路径质量作为判决条件引入到AODV协议中,最终形成基于链路质量的路由算法.仿真表明改进的算法可提高选择路径的可靠性,降低丢包率和平均端到端时延.%Because of node mobility and energy limitation lead to node failure and transmission link instability in Ad hoc Net?works, improve original Link Lifetime calculation method, calculate path quality with node residual energy, the path quality as a judgment condition introduced into AODV protocol,Ultimately form routing algorithm based on link quality. Simulation results show that the improved algorithm can improve the selection path reliability and reduce the packet loss rate and the average end-to-end delay.

  6. EBAA:An effcient broadcast authentication scheme for ADS-B communication based on IBS-MR

    Institute of Scientific and Technical Information of China (English)

    Yang Haomiao; Huang Rongshun; Wang Xiaofen; Deng Jiang; Chen Ruidong

    2014-01-01

    Automatic dependent surveillance-broadcast (ADS-B) systems can broadcast satellite-based aircraft position, identification, etc., periodically, and are now on track to replace radar to become the backbone of next-generation air traffic management (ATM) systems. However, ADS-B systems suffer severe cyber-security problems due to the broadcast-type data link and the lack of designed-in security measures. Especially, since ADS-B messages are unauthenticated, it is easy to insert fake aircraft into a system via spoofing or insertion of false messages. Unfortu-nately, the authentication for ADS-B messages has not yet been well studied. In this paper, based on identity-based signature with message recovery (IBS-MR), an efficient broadcast authentication scheme for ADS-B messages is proposed. The security analysis demonstrates that the scheme can achieve authenticity and integrity of ADS-B broadcast messages, as well as adaptive evolution of broadcasters’ private keys. The performance evaluation shows that the scheme is computationally efficient for typical avionics devices with limited resources. Furthermore, the scheme achieves low communication overhead since broadcast messages can be recovered from signatures, and thus it is suitable for low-bandwidth ADS-B data link.

  7. The Sensitivity of Adolescent School-Based Hearing Screens Is Significantly Improved by Adding High Frequencies.

    Science.gov (United States)

    Sekhar, Deepa L; Zalewski, Thomas R; Beiler, Jessica S; Czarnecki, Beth; Barr, Ashley L; King, Tonya S; Paul, Ian M

    2016-12-01

    High frequency hearing loss (HFHL), often related to hazardous noise, affects one in six U.S. adolescents. Yet, only 20 states include school-based hearing screens for adolescents. Only six states test multiple high frequencies. Study objectives were to (1) compare the sensitivity of state school-based hearing screens for adolescents to gold standard sound-treated booth testing and (2) consider the effect of adding multiple high frequencies and two-step screening on sensitivity/specificity. Of 134 eleventh-grade participants (2013-2014), 43 of the 134 (32%) did not pass sound-treated booth testing, and 27 of the 43 (63%) had HFHL. Sensitivity/specificity of the most common protocol (1,000, 2,000, 4,000 Hz at 20 dB HL) for these hearing losses was 25.6% (95% confidence interval [CI] = [13.5, 41.2]) and 85.7% (95% CI [76.8, 92.2]), respectively. A protocol including 500, 1,000, 2,000, 4,000, 6,000 Hz at 20 dB HL significantly improved sensitivity to 76.7% (95% CI [61.4, 88.2]), p < .001. Two-step screening maintained specificity (84.6%, 95% CI [75.5, 91.3]). Adolescent school-based hearing screen sensitivity improves with high frequencies.

  8. Intelligent self-organization methods for wireless ad hoc sensor networks based on limited resources

    Science.gov (United States)

    Hortos, William S.

    2006-05-01

    A wireless ad hoc sensor network (WSN) is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. To a greater degree than the terminals found in mobile ad hoc networks (MANETs) for communications, sensor nodes are resource-constrained, with limited computational processing, bandwidth, memory, and power, and are typically unattended once in operation. Consequently, the level of information exchange among nodes, to support any complex adaptive algorithms to establish network connectivity and optimize throughput, not only deplete those limited resources and creates high overhead in narrowband communications, but also increase network vulnerability to eavesdropping by malicious nodes. Cooperation among nodes, critical to the mission of sensor networks, can thus be disrupted by the inappropriate choice of the method for self-organization. Recent published contributions to the self-configuration of ad hoc sensor networks, e.g., self-organizing mapping and swarm intelligence techniques, have been based on the adaptive control of the cross-layer interactions found in MANET protocols to achieve one or more performance objectives: connectivity, intrusion resistance, power control, throughput, and delay. However, few studies have examined the performance of these algorithms when implemented with the limited resources of WSNs. In this paper, self-organization algorithms for the initiation, operation and maintenance of a network topology from a collection of wireless sensor nodes are proposed that improve the performance metrics significant to WSNs. The intelligent algorithm approach emphasizes low computational complexity, energy efficiency and robust adaptation to change, allowing distributed implementation with the actual limited resources of the cooperative nodes of the network. Extensions of the

  9. Total, added, and free sugars: are restrictive guidelines science-based or achievable?

    Science.gov (United States)

    Erickson, Jennifer; Slavin, Joanne

    2015-04-01

    Sugar consumption, especially added sugars, is under attack. Various government and health authorities have suggested new sugar recommendations and guidelines as low as 5% of total calories from free sugars. Definitions for total sugars, free sugars, and added sugars are not standardized, nor are there accepted nutrient databases for this information. Our objective was to measure total sugars and added sugars in sample meal plans created by the United States Department of Agriculture (USDA) and the Academy of Nutrition and Dietetics (AND). Utilizing the Nutrition Data System for Research (NDSR) nutritional database, results found that plans created by the USDA and AND averaged 5.1% and 3.1% calories from added sugar, 8.7% and 3.1% from free sugar, and 23.3% and 21.1% as total sugars respectively. Compliance with proposed added sugar recommendations would require strict dietary compliance and may not be sustainable for many Americans. Without an accepted definition and equation for calculating added sugar, added sugar recommendations are arbitrary and may reduce intakes of nutrient-rich, recommended foods, such as yogurt, whole grains, and tart fruits including cranberries, cherries, and grapefruit. Added sugars are one part of excess calorie intake; however, compliance with low added sugar recommendations may not be achievable for the general public.

  10. Total, Added, and Free Sugars: Are Restrictive Guidelines Science-Based or Achievable?

    Directory of Open Access Journals (Sweden)

    Jennifer Erickson

    2015-04-01

    Full Text Available Sugar consumption, especially added sugars, is under attack. Various government and health authorities have suggested new sugar recommendations and guidelines as low as 5% of total calories from free sugars. Definitions for total sugars, free sugars, and added sugars are not standardized, nor are there accepted nutrient databases for this information. Our objective was to measure total sugars and added sugars in sample meal plans created by the United States Department of Agriculture (USDA and the Academy of Nutrition and Dietetics (AND. Utilizing the Nutrition Data System for Research (NDSR nutritional database, results found that plans created by the USDA and AND averaged 5.1% and 3.1% calories from added sugar, 8.7% and 3.1% from free sugar, and 23.3% and 21.1% as total sugars respectively. Compliance with proposed added sugar recommendations would require strict dietary compliance and may not be sustainable for many Americans. Without an accepted definition and equation for calculating added sugar, added sugar recommendations are arbitrary and may reduce intakes of nutrient-rich, recommended foods, such as yogurt, whole grains, and tart fruits including cranberries, cherries, and grapefruit. Added sugars are one part of excess calorie intake; however, compliance with low added sugar recommendations may not be achievable for the general public.

  11. Trust Based Scheme for QoS Assurance in Mobile Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Sridhar Subramanian

    2012-02-01

    Full Text Available A mobile ad-hoc network (MANET is a peer-to-peer wireless network where nodes can communicate with each other without the use of infrastructure such as access points or base stations. These networks are self-configuring, capable of self-directed operation and hastily deployable. Nodes cooperate to provide connectivity, operates without centralized administration. Nodes are itinerant, topology can be very dynamic and nodes must be able to relay traffic since communicating nodes might be out of range. The dynamic nature of MANET makes network open to attacks and unreliability. Routing is always the most significant part for any networks. Each node should not only work for itself, but should be cooperative with other nodes. Node misbehaviour due to selfish or malicious intention could significantly degrade the performance of MANET. The Qos parameters like PDR, throughput and delay are affected directly due to such misbehaving nodes. We focus on trust management framework, which is intended to cope with misbehaviour problem of node and increase the performance of MANETs. A trust-based system can be used to track this misbehaving of nodes, spot them and isolate them from routing and provide reliability. In this paper a Trust Based Reliable AODV [TBRAODV] protocol is presented which implements a trust value for each node. For every node trust value is calculated and based trust valuenodes are allowed to participate in routing or else identified to become a misbehaving node. This enhances reliability in AODV routing and results in increase of PDR, decrease in delay and throughput is maintained. This work is implemented and simulated on NS-2. Based on simulation results, the proposed protocol provides more consistent and reliable data transfer compared with general AODV, if there are misbehaving nodes in the MANET.

  12. Clustering and OFDMA-based MAC protocol (COMAC for vehicular ad hoc networks

    Directory of Open Access Journals (Sweden)

    Abdel Hafeez Khalid

    2011-01-01

    Full Text Available Abstract The IEEE community is working on the wireless access in vehicular environments as a main technology for vehicular ad hoc networks. The medium access control (MAC protocol of this system known as IEEE 802.11p is based on the distributed coordination function (DCF of the IEEE 802.11 and enhanced DCF of the IEEE 802.11e that have low performance especially in high-density networks with nodes of high mobility. In this paper, we propose a novel MAC protocol where nodes dynamically organize themselves into clusters. Cluster heads are elected based on their stability on the road with minimal overhead since all clustering information is embedded in control channel's safety messages. The proposed MAC protocol is adaptable to drivers' behavior on the road and has learning mechanism for predicting the future speed and position of all cluster members using the fuzzy logic inference system. By using OFDMA, each cluster will use a set of subcarriers that are different from the neighboring clusters to eliminate the hidden terminal problem. Increasing the system reliability, reducing the time delay for vehicular safety applications and efficiently clustering vehicles in highly dynamic and dense networks in a distributed manner are the main contributions of our proposed MAC protocol.

  13. A quality of service routing protocol based on mobility prediction in mobile ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    王建新; 邓曙光; 陈松乔; 陈建二

    2003-01-01

    A QoS routing protocol based on mobility prediction is proposed. The protocol selects the steadiest path based on mobility prediction and QoS requirements on bandwidth, delay, and so forth. The main properties of the protocol as follows. (1) Each node just broadcasts its own information, so the packet is very small and can get to the destination in a very short time. (2)When another path is built for the same QoS requirements, the original path has higher priority.(3) The update messages are reduced by using mobility prediction. (4) Data packets carry the information of link change using piggyback, which is helpful for forecasting the link status more accurately. (5) When source node gets Resource-Reserve and reconnect packets at the same time, it selects reconnect packet over Resource-Reserve packet. The results of simulation show that the protocol has good network performance with low control overload, and efficiently supports transmitting multimedia with QoS requirements in mobile ad hoc networks.

  14. Cooperative Caching in Mobile Ad Hoc Networks Based on Data Utility

    Directory of Open Access Journals (Sweden)

    Narottam Chand

    2007-01-01

    Full Text Available Cooperative caching, which allows sharing and coordination of cached data among clients, is a potential technique to improve the data access performance and availability in mobile ad hoc networks. However, variable data sizes, frequent data updates, limited client resources, insufficient wireless bandwidth and client's mobility make cache management a challenge. In this paper, we propose a utility based cache replacement policy, least utility value (LUV, to improve the data availability and reduce the local cache miss ratio. LUV considers several factors that affect cache performance, namely access probability, distance between the requester and data source/cache, coherency and data size. A cooperative cache management strategy, Zone Cooperative (ZC, is developed that employs LUV as replacement policy. In ZC one-hop neighbors of a client form a cooperation zone since the cost for communication with them is low both in terms of energy consumption and message exchange. Simulation experiments have been conducted to evaluate the performance of LUV based ZC caching strategy. The simulation results show that, LUV replacement policy substantially outperforms the LRU policy.

  15. An Update based Energy-Efficient Reactive Routing Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Dhirendra Kumar Sharma

    2013-09-01

    Full Text Available Low cost energy-efficient (power based routing protocols of mobile ad hoc networks (MANETs increase the lifetime of static networks by using received signal strength (RSS and battery power status (PS. They require GPS service to find the exact location of mobile nodes. The GPS devices themselves consume power because they need excessive updates to find the stationary nodes for efficient routing. To overcome this, RSS is being used as a metric, followed by, residual battery power. The recent protocols, based on these concepts, provide energy efficient routes during the route discovery phase only. Topological changes make these routes weak in due course of time. To update routes, HELLO process can be used, which however creates unnecessary overhead, delay and consumes power. Hence, these protocols do not update the routes. We propose an energy-efficient reactive routing protocol that uses the RSS and PS of mobile nodes. Proposed Link Failure Prediction (LFP algorithm uses the link-layer feedback system to update active routes. We use ns2 for simulation of the proposed algorithm. Comparing the results of proposed scheme and existing scheme, in terms of energy consumption, link failure probability, and retransmission of packets, we observe that the proposed scheme outperforms the existing one.

  16. Adding-point strategy for reduced-order hypersonic aerothermodynamics modeling based on fuzzy clustering

    Science.gov (United States)

    Chen, Xin; Liu, Li; Zhou, Sida; Yue, Zhenjiang

    2016-09-01

    Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.

  17. IDMA: improving the defense against malicious attack for mobile ad hoc networks based on ARIP protocol

    Science.gov (United States)

    Peng, Chaorong; Chen, Chang Wen

    2008-04-01

    Malicious nodes are mounting increasingly sophisticated attacking operations on the Mobile Ad Hoc Networks (MANETs). This is mainly because the IP-based MANETs are vulnerable to attacks by various malicious nodes. However, the defense against malicious attack can be improved when a new layer of network architecture can be developed to separate true IP address from disclosing to the malicious nodes. In this paper, we propose a new algorithm to improve the defense against malicious attack (IDMA) that is based on a recently developed Assignment Router Identify Protocol (ARIP) for the clustering-based MANET management. In the ARIP protocol, we design the ARIP architecture based on the new Identity instead of the vulnerable IP addresses to provide the required security that is embedded seamlessly into the overall network architecture. We make full use of ARIP's special property to monitor gateway forward packets by Reply Request Route Packets (RREP) without additional intrusion detection layer. We name this new algorithm IDMA because of its inherent capability to improve the defense against malicious attacks. Through IDMA, a watching algorithm can be established so as to counterattack the malicious node in the routing path when it unusually drops up packets. We provide analysis examples for IDMA for the defense against a malicious node that disrupts the route discovery by impersonating the destination, or by responding with state of corrupted routing information, or by disseminating forged control traffic. The IDMA algorithm is able to counterattack the malicious node in the cases when the node lunch DoS attack by broadcast a large number of route requests, or make Target traffic congestion by delivering huge mount of data; or spoof the IP addresses and send forge packets with a fake ID to the same Target causing traffic congestion at that destination. We have implemented IDMA algorism using the GloMoSim simulator and have demonstrated its performance under a variety of

  18. Behavioral analysis of Wistar rats fed with a flaxseed based diet added to an environmental enrichment.

    Science.gov (United States)

    Azevedo de Meneses, J; Junqueira Lopes, C A; Coca Velarde, L G; Teles Boaventura, G

    2011-01-01

    Flaxseed has a high content of n-3 fatty acids and its intake associated with an environmental enrichment may promote distinct behavioral results upon habituation and animal behavior. This work aimed to evaluating animal behavior under the use of these two tools in the Open Field Test. Thirty-six male Wistar rats were divided into 6 groups (n = 6): FEEG, receiving chow made up of flaxseed and kept in enriched environment; FSEG, receiving flaxseed based diet and kept in a standard environment; CEEG, receiving casein based diet and kept in enriched environment; CSEG, receiving casein based chow and kept in standard environment; MCEEG, receiving chow made up of casein but modified so as to provide the same content of fibers and lipids found in flaxseed diet and kept in enriched environment; MCSEG, receiving modified casein based diet and kept in standard environment. All animals were kept under controlled temperature, collective cages and dark/light cycle, receiving chow and water ad libitum, except for MCEEG and MCSEG, which were pair fed with FEEG and FSEG, respectively. Chow intake and animal body weight were evaluated twice in a week. Animals were maintained in these groups from the first until the second month of life, by the time when 3 day tests in Open Field Test began. Finishing the tests, animals were sacrificed and their brains were obtained in order to calculate the relative brain weight. Our results show an interplay between flaxseed and environmental enrichment in habituation to a new environment, making the animals more manageable and less stressed.

  19. High resolution A/D conversion based on piecewise conversion at lower resolution

    Science.gov (United States)

    Terwilliger, Steve

    2012-06-05

    Piecewise conversion of an analog input signal is performed utilizing a plurality of relatively lower bit resolution A/D conversions. The results of this piecewise conversion are interpreted to achieve a relatively higher bit resolution A/D conversion without sampling frequency penalty.

  20. Adding Missing-Data-Relevant Variables to FIML-Based Structural Equation Models

    Science.gov (United States)

    Graham, John W.

    2003-01-01

    Conventional wisdom in missing data research dictates adding variables to the missing data model when those variables are predictive of (a) missingness and (b) the variables containing missingness. However, it has recently been shown that adding variables that are correlated with variables containing missingness, whether or not they are related to…

  1. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Mechanism of Preferential Connection

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, we introduce a modified small-world network added with new links with preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. Several dynamical character of the model such as the evolution graph, fo avalanche, the critical exponent D and τ, and the distribution of mutation times of all the nodes, show particular behaviors different from those of the model based on the regular network and the small-world network.

  2. Research on TCP Performance Based on Ad Hoc Network%基于Ad Hoc网络的TCP性能研究

    Institute of Scientific and Technical Information of China (English)

    徐阳

    2011-01-01

    Ad Hoc网络的拓扑结构动态变化使得传统的TCP协议不再适用.文章首先介绍了TCP协议应用在Ad Hoc网络中存在的问题,然后分析了Ad Hoc网络中TCP协议的性能,并讨论了其改进的策略和方法.%Since Ad Hoc network topology changes dynamically,the traditional TCP protocol no longer applies.The problems of TCP existing in Ad Hoc network are expounded firstly.Then,performance of TCP in Ad Hoc network is analyzed and its improvement policies and methods are discussed.

  3. 基于定位信息的Ad hoc路由协议%Ad hoc Routing Protocol Based on Location Information

    Institute of Scientific and Technical Information of China (English)

    李文杰

    2011-01-01

    基于定位信息的路由协议的功能大大优于传统的Ad hoc路由协议,但基于定位信息的路由协议不能用于高风险环境.本文所介绍的Ad hoc网络基于定位信息的安全型路由协议"Secure Position Aided Ad hoc Routing"(SPAAR)目的在于提高移动Ad hoc路由的安全性、有效性和性能.

  4. A maintenance scheme of communication link in mobile robot ad hoc networks based on potential field

    Science.gov (United States)

    Jiang, Hong; Jin, WenPing; Yang, GyoYing; Li, LeiMin

    2007-12-01

    Maintaining communication link in mobile robot networks between task robots and a control center is very important in some urgent application occasions such as remote danger detections. To offer a reliable multi-hop communication link, a link maintaining scheme based on artificial potential field is presented. The scheme is achieved by a task robot and communication relay ones. The task robot performs predefined tasks, and relay ones are simple robots which form a communication relay chain. When robots move towards destination in formation, a kind of attractive force created by communication quality is added to traditional potential field, and relay robots follow the task robot and automatically stop at adequate locations to form a relay chain from the control station to the task robot. In order to increase relay usage efficiency, when some relays are replaced by other short cut relays, the redundant relays can be reused by initiating another moving toward specified location. Simulation results show that the scheme can provide a reliable multi-hop communication link, and that the communication connection can be obtained through minimal number of relays.

  5. QoS Support in TDMA-Based Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Imad Jawhar; Jie Wu

    2005-01-01

    Mobile ad hoc networks (MANETs) are gaining a lot of attention in research lately due to their importance in enabling mobile wireless nodes to communicate without any existing wired or predetermined infrastructures. Furthermore,in order to support the growing need for multimedia and realtime applications, quality of service (QoS) support by the networking protocol is required. Several important QoS parameters that are needed by such applications can be identified.They include bandwidth, end-to-end delay, delay jitter, and bit error rate. A good amount of research has been developed in this area covering different issues and challenges such as developing routing protocols that support bandwidth reservation and delay management. In this paper, the current state of research for QoS support in TDMA-based MANETs at different layers of the networking model is presented and categorized. In addition, the current issues and future challenges involved in this exciting area of research are also included.

  6. An Efficient Position based Power Aware Routing Algorithm in Mobile Ad-hoc Networks

    Directory of Open Access Journals (Sweden)

    Md. Mahbubur Rahman

    2016-07-01

    Full Text Available In this paper we introduced an efficient scheme based on a weighted metric of remaining battery power, speed and distance of nodes for determining routes in wireless Mobile Ad hoc Networks (MANET. For the cases where significant difference in the velocities of the communicating nodes or the battery power of the intermediate nodes is low, traditional schemes fail to establish the communication among nodes with reliable QoS. We proposed a new algorithm that uses weighted combination of metrics of distance, velocity and battery power in selecting the route over earlier MFR (Most Forward within Radius method. The proposed scheme encompasses the load balancing issues and eventually it increases the network lifetime and network performance. Simulation experiment showed that the proposed algorithm reduces the packet loss than that of existing MFR algorithm. Experimental results also revealed that besides packet loss, the proposed strategy achieves higher throughput (14.35% rate than that of existing MFR. Furthermore, usages of these new metrics ensure the higher mean time to node failure.

  7. Data delivery method based on neighbor nodes' information in a mobile ad hoc network.

    Science.gov (United States)

    Kashihara, Shigeru; Hayashi, Takuma; Taenaka, Yuzo; Okuda, Takeshi; Yamaguchi, Suguru

    2014-01-01

    This paper proposes a data delivery method based on neighbor nodes' information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow.

  8. Documentary and instrumental-based drought indices for the Czech Lands back to AD 1501

    Science.gov (United States)

    Brázdil, Rudolf; Dobrovolný, Petr; Trnka, Miroslav; Büntgen, Ulf; Řezníčková, Ladislava; Kotyza, Oldřich; Valášek, Hubert; Štěpánek, Petr

    2016-04-01

    This study addresses the reconstruction of four slightly different drought indices in the Czech Lands (recent Czech Republic) back to 1501 AD. Reconstructed monthly temperatures for central Europe that are representative for the Czech territory, together with reconstructed seasonal precipitation totals from the same area, are used to calculate monthly, seasonal and annual drought indices (SPI, SPEI, Z-index, and PDSI). The resulting time-series reflect interannual-to multi-decadal drought variability. The driest episodes cluster around the beginning and end of the 18th century, while 1540 emerges as a particularly dry extreme year. The temperature-driven dryness of the past three decades is well captured by SPEI, Z-index and PDSI, whereas precipitation totals show no significant trend during this period (as reflected in SPI). Data and methodological uncertainty associated with Czech drought indices, as well as their position in a greater European context, are critically outlined. Further discussion is devoted to comparison with fir tree-rings from southern Moravia and a spatial subset of the "Old World Drought Atlas" (OWDA), which reveals significant correlation coefficients, of around 0.40 and 0.50, respectively. This study introduces a new documentary-based approach for the robust extension of standardized drought indices back into pre-instrumental times, which we also believe has great potential in other parts of the world where high-resolution paleoclimatic insight remains as yet limited.

  9. A fuzzy logic based clustering strategy for improving vehicular ad-hoc network performance

    Indian Academy of Sciences (India)

    Ali Çalhan

    2015-04-01

    This paper aims to improve the clustering of vehicles by using fuzzy logic in Vehicular Ad-Hoc Networks (VANETs) for making the network more robust and scalable. High mobility and scalability are two vital topics to be considered while providing efficient and reliable communication in VANETs. Clustering is of crucial significance in order to cope with the dynamic features of the VANET topologies. Plenty of parameters related to user preferences, network conditions and application requirements such as speed of mobile nodes, distance to cluster head, data rate and signal strength must be evaluated in the cluster head selection process together with the direction parameter for highly dynamic VANET structures. The prominent parameters speed, acceleration, distance and direction information are taken into account as inputs of the proposed cluster head selection algorithm. The simulation results show that developed fuzzy logic (FL) based cluster head selection algorithm (CHSA) has stable performance in various scenarios in VANETs. This study has also shown that the developed CHSAFL satisfies well the highly demanding requirements of both low speed and high speed vehicles on two-way multilane highway

  10. Mobile Ad Hoc Network Energy Cost Algorithm Based on Artificial Bee Colony

    Directory of Open Access Journals (Sweden)

    Mustafa Tareq

    2017-01-01

    Full Text Available A mobile ad hoc network (MANET is a collection of mobile nodes that dynamically form a temporary network without using any existing network infrastructure. MANET selects a path with minimal number of intermediate nodes to reach the destination node. As the distance between each node increases, the quantity of transmission power increases. The power level of nodes affects the simplicity with which a route is constituted between a couple of nodes. This study utilizes the swarm intelligence technique through the artificial bee colony (ABC algorithm to optimize the energy consumption in a dynamic source routing (DSR protocol in MANET. The proposed algorithm is called bee DSR (BEEDSR. The ABC algorithm is used to identify the optimal path from the source to the destination to overcome energy problems. The performance of the BEEDSR algorithm is compared with DSR and bee-inspired protocols (BeeIP. The comparison was conducted based on average energy consumption, average throughput, average end-to-end delay, routing overhead, and packet delivery ratio performance metrics, varying the node speed and packet size. The BEEDSR algorithm is superior in performance than other protocols in terms of energy conservation and delay degradation relating to node speed and packet size.

  11. A new Hierarchical Group Key Management based on Clustering Scheme for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Ayman EL-SAYED

    2014-05-01

    Full Text Available The migration from wired network to wireless network has been a global trend in the past few decades because they provide anytime-anywhere networking services. The wireless networks are rapidly deployed in the future, secure wireless environment will be mandatory. As well, The mobility and scalability brought by wireless network made it possible in many applications. Among all the contemporary wireless networks,Mobile Ad hoc Networks (MANET is one of the most important and unique applications. MANET is a collection of autonomous nodes or terminals which communicate with each other by forming a multihop radio network and maintaining connectivity in a decentralized manner. Due to the nature of unreliable wireless medium data transfer is a major problem in MANET and it lacks security and reliability of data. The most suitable solution to provide the expected level of security to these services is the provision of a key management protocol. A Key management is vital part of security. This issue is even bigger in wireless network compared to wired network. The distribution of keys in an authenticated manner is a difficult task in MANET. When a member leaves or joins the group, it needs to generate a new key to maintain forward and backward secrecy. In this paper, we propose a new group key management schemes namely a Hierarchical, Simple, Efficient and Scalable Group Key (HSESGK based on clustering management scheme for MANETs and different other schemes are classified. Group members deduce the group key in a distributed manner.

  12. OMNeT++-Based Cross-Layer Simulator for Content Transmission over Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Massin R

    2010-01-01

    Full Text Available Flexbility and deployment simplicity are among the numerous advantages of wireless links when compared to standard wired communications. However, challenges do remain high for wireless communications, in particular due to the wireless medium inherent unreliability, and to the desired flexibility, which entails complex protocol procedures. In that context simulation is an important tool to understand and design the protocols that manage the wireless networks. This paper introduces a new simulation framework based on the OMNeT++ simulator whose goal is to enable the study of data and multimedia content transmission over hybrid wired/wireless ad hoc networks, as well as the design of innovative radio access schemes. To achieve this goal, the complete protocol stack from the application to the physical layer is simulated, and the real bits and bytes of the messages transferred on the radio channel are exchanged. To ensure that this framework is reusable and extensible in future studies and projects, a modular software and protocol architecture has been defined. Although still in progress, our work has already provided some valuable results concerning cross layer HARQ/MAC protocol performance and video transmission over the wireless channel, as illustrated by results examples.

  13. Added value of lignin as lignin-based hybrid polyurethane for a compatibilizing agent

    Science.gov (United States)

    Ilmiati, S.; Haris Mustafa, J.; Yaumal, A.; Hanum, F.; Chalid, M.

    2017-07-01

    As biomass-based material, lignin contains abundant hydroxyl groups promising to be used as chain extender in building hybrid polyurethanes. Consisting of polyehtylene glycol (PEG) content as hydrophobic part and lignin as hydrophilic part, the hybrid PU is expected to be as a novel compatibilizing agent in new materials production such as polyblends and composites. The hybrid PU was synthesized via two reaction stages, viz. pre-polyurethanization through reacting 4,4'-Methylenebis (Cyclohexyl Isocyanate) (HMDI) and PEG as polyol, and chain extention through adding lignin in the pre-polyurethanization system. The composition effect of lignin in hybrid PU syntehsis, to chemical structure corelated to hydrophobic to hydrophilic ratio, thermal and morphological properties, was evaluated by measuring NMR, FTIR, DSC, TGA and FE-SEM. The experiments showed that addition of lignin was able to extend the pre-polyurethane into hybrid polyurethane and to increase the lignin/polyol ratio in the hybrid polyurethanes, which were indicated by NMR and FTIR Analysis. And change of the ratio lead to increase the glass transition from 60.9 until 62.1°C and degradation temperature from 413.9 until 416.0°C. Observation of the morphology implied that addition of lignin gave more agglomerations. A Further investigation for this characterization study should be focused on a feasibility for this modified lignin as a novel compatibilizing agent.

  14. Agent based Bandwidth Reservation Routing Technique in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Vishnu Kumar Sharma,

    2011-12-01

    Full Text Available In mobile ad hoc networks (MANETs, inefficient resource allocation causes heavy losses to the service providers and results in inadequate user proficiency. For improving and automating the quality of service of MANETs, efficient resource allocation techniques are required. In this paper, we propose an agent based bandwidth reservation technique for MANET. The mobile agent from the source starts forwarding the data packets through the path which has minimum cost, congestion and bandwidth. The status of every node is collected which includes the bottleneck bandwidth field and the intermediate node computes the available bandwidth on the link. At the destination, after updating the new bottleneck bandwidth field, the data packet is feedback to the source. In resource reservation technique, if the available bandwidth is greater than bottleneck bandwidth, then bandwidth reservation for the flow is done. Using rate monitoring and adjustment methodologies, rate control is performed for the congested flows. By simulation results, we show that the resource allocation technique reduces the losses and improves the network performance.

  15. Tailoring the implementation of new biomarkers based on their added predictive value in subgroups of individuals.

    Directory of Open Access Journals (Sweden)

    A van Giessen

    Full Text Available The value of new biomarkers or imaging tests, when added to a prediction model, is currently evaluated using reclassification measures, such as the net reclassification improvement (NRI. However, these measures only provide an estimate of improved reclassification at population level. We present a straightforward approach to characterize subgroups of reclassified individuals in order to tailor implementation of a new prediction model to individuals expected to benefit from it.In a large Dutch population cohort (n = 21,992 we classified individuals to low (< 5% and high (≥ 5% fatal cardiovascular disease risk by the Framingham risk score (FRS and reclassified them based on the systematic coronary risk evaluation (SCORE. Subsequently, we characterized the reclassified individuals and, in case of heterogeneity, applied cluster analysis to identify and characterize subgroups. These characterizations were used to select individuals expected to benefit from implementation of SCORE.Reclassification after applying SCORE in all individuals resulted in an NRI of 5.00% (95% CI [-0.53%; 11.50%] within the events, 0.06% (95% CI [-0.08%; 0.22%] within the nonevents, and a total NRI of 0.051 (95% CI [-0.004; 0.116]. Among the correctly downward reclassified individuals cluster analysis identified three subgroups. Using the characterizations of the typically correctly reclassified individuals, implementing SCORE only in individuals expected to benefit (n = 2,707,12.3% improved the NRI to 5.32% (95% CI [-0.13%; 12.06%] within the events, 0.24% (95% CI [0.10%; 0.36%] within the nonevents, and a total NRI of 0.055 (95% CI [0.001; 0.123]. Overall, the risk levels for individuals reclassified by tailored implementation of SCORE were more accurate.In our empirical example the presented approach successfully characterized subgroups of reclassified individuals that could be used to improve reclassification and reduce implementation burden. In particular when newly

  16. Mitigating Malicious Attacks Using Trust Based Secure-BEFORE Routing Strategy in Mobile Ad Hoc Networks

    National Research Council Canada - National Science Library

    Shah, Rutuja; Subramaniam, Sumathy; Lekala Dasarathan, Dhinesh Babu

    2016-01-01

    Mobile ad hoc Networks (MANET), being infrastructureless and dynamic in nature, are predominantly susceptible to attacks such as black hole, worm hole, cunning gray hole attack at source or destination...

  17. An ad-hoc opportunistic dissemination protocol for smartphone-based participatory traffic monitoring

    NARCIS (Netherlands)

    Türkes, Okan; Seraj, Fatjon; Scholten, Hans; Meratnia, Nirvana; Havinga, Paul J.M.

    2015-01-01

    This study introduces an ad-hoc opportunistic data dissemination protocol, called VADISS, that facilitates participatory traffic monitoring applications with smartphones. As a ubiquitous alternative to existing vehicular networking methods, VADISS uses the default WiFi interfaces universally adopted

  18. A Group Based Key Sharing and Management Algorithm for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Zeeshan Shafi Khan

    2014-01-01

    Full Text Available Vehicular ad hoc networks (VANETs are one special type of ad hoc networks that involves vehicles on roads. Typically like ad hoc networks, broadcast approach is used for data dissemination. Blind broadcast to each and every node results in exchange of useless and irrelevant messages and hence creates an overhead. Unicasting is not preferred in ad-hoc networks due to the dynamic topology and the resource requirements as compared to broadcasting. Simple broadcasting techniques create several problems on privacy, disturbance, and resource utilization. In this paper, we propose media mixing algorithm to decide what information should be provided to each user and how to provide such information. Results obtained through simulation show that fewer number of keys are needed to share compared to simple broadcasting. Privacy is also enhanced through this approach.

  19. An Empirical Comparative Study of Checklist-based and Ad Hoc Code Reading Techniques in a Distributed Groupware Environment

    Directory of Open Access Journals (Sweden)

    Adenike O. Osofisan

    2009-09-01

    Full Text Available Software inspection is a necessary and important tool for software quality assurance. Since it was introduced by Fagan at IBM in 1976, arguments exist as to which method should be adopted to carry out the exercise, whether it should be paper-based or tool-based, and what reading technique should be used on the inspection document. Extensive works have been done to determine the effectiveness of reviewers in paper-based environment when using ad hoc and checklist reading techniques. In this work, we take the software inspection research further by examining whether there is going to be any significant difference in defect detection effectiveness of reviewers when they use either ad hoc or checklist reading techniques in a distributed groupware environment. Twenty final year undergraduate students of computer science, divided into ad hoc and checklist reviewers groups of ten members each were employed to inspect a medium-sized java code synchronously on groupware deployed on the Internet. The data obtained were subjected to tests of hypotheses using independent t-test and correlation coefficients. Results from the study indicate that there are no significant differences in the defect detection effectiveness, effort in terms of time taken in minutes and false positives reported by the reviewers using either ad hoc or checklist based reading techniques in the distributed groupware environment studied.Key words: Software Inspection, Ad hoc, Checklist, groupware.

  20. An Empirical Comparative Study of Checklist based and Ad Hoc Code Reading Techniques in a Distributed Groupware Environment

    CERN Document Server

    Akinola, Olalekan S

    2009-01-01

    Software inspection is a necessary and important tool for software quality assurance. Since it was introduced by Fagan at IBM in 1976, arguments exist as to which method should be adopted to carry out the exercise, whether it should be paper based or tool based, and what reading technique should be used on the inspection document. Extensive works have been done to determine the effectiveness of reviewers in paper based environment when using ad hoc and checklist reading techniques. In this work, we take the software inspection research further by examining whether there is going to be any significant difference in defect detection effectiveness of reviewers when they use either ad hoc or checklist reading techniques in a distributed groupware environment. Twenty final year undergraduate students of computer science, divided into ad hoc and checklist reviewers groups of ten members each were employed to inspect a medium sized java code synchronously on groupware deployed on the Internet. The data obtained were...

  1. QoS Issues Reserch Based on Mobile Ad Hoc Network%基于Ad Hoc网络QoS信令机制研究

    Institute of Scientific and Technical Information of China (English)

    沈敏洁; 顾海军

    2006-01-01

    针对移动Ad Hoc网络中移动节点的自由移动和拓扑结构的动态变化所造成的已经建立的QoS(Quality of Service)路径断开致使通信中断、时延、抖动等问题,对可支持Ad Hoc网络的QoS信令机制进行深入的探讨,结合Ad Hoc网络拓扑结构动态改变、传输带宽有限以及能量受限等问题,讨论了现存计算机网络综合服务和区分服务应用于Ad Hoc网络的优劣,提出了Ad Hoc网络QoS信令设计需要考虑的问题.研究表明:MRSVP(Mobile Resource ReSerVation Protocol)和DRSVP(Dynami Resource ReSerVation Protocol)较RSVP(Resource ReSerVation Protocol)在协议功能上有很大的增强;而FQMM(Flexible Quality of Service Model for Mobile Ad Hoc Networks)则结合了IntServ和DifServ的优点;三者对提高Ad Hoc网络的QoS,均起到很大的作用.

  2. The impact of adding an extra dimension to a preference-based measure.

    Science.gov (United States)

    Brazier, John; Rowen, Donna; Tsuchiya, Aki; Yang, Yaling; Young, Tracy A

    2011-07-01

    The ability to compare incremental changes in Quality Adjusted Life Years (QALYs) generated by different condition-specific preference-based measures (CSPBMs), or indeed between generic measures, is often criticised even where the valuation methods and source of values are the same. A key concern is the impact of excluding key dimensions from a descriptive system. This study examines the impact of adding a generic pain/discomfort dimension to a CSPBM, the AQL-5D (an asthma-specific CSPBM), by valuing samples of states from the AQL-5D with and without the new dimension using an interviewer administered time trade-off with a sample of the U.K. general public. 180 respondents provided 720 valuations for states with and without pain/discomfort. As expected the additional pain/discomfort dimension was found to have a significant and relatively large coefficient. More importantly for comparing changes in QALYs across populations the addition of pain/discomfort significantly impacts on the coefficients of the other dimensions and the degree of impact differs by dimension and severity level. The net effect on the utility value depends on the severity of their state: the addition of pain/discomfort at level 1 (no pain/discomfort) or 2 (moderate pain/discomfort) significantly increased the mean health state values in an asthma patient population; whereas level 3 pain/discomfort (extreme) reduced values. Comparability between measures requires that the impact of different dimensions on preferences is additive, whether or not they are included in the classification system. Our results cast doubt on this assumption, implying that the chosen measure must contain all important and relevant dimensions in its classification system.

  3. 基于移动ad-hoc网络的车辆定位%Positioning of vehicles based on ad-hoc networks

    Institute of Scientific and Technical Information of China (English)

    孙剑明; 赵琳

    2013-01-01

    When the vehicles cannot receive their own position information by GPS, it is hard to get useful tips on traffic risk. This paper proposes a new positioning method based on car mobile ad-hoc network, which can obtain approximate location of a car as a network node. This method uses an improved optimization propagation algorithm of alarm messages, which helps the vehicles that are in danger or traffic jam while can not position by GPS to receive alarm messages. Simulation test shows that if 40% of all vehicles in the network can receive positioning messages by GPS, all vehicles can correctly and completely get alarm messages. In the condition of fog, accident or other traffic jam, this method can stop vehicles from traffic jam and prevent drivers form being in an accident.%当车辆不能通过GPS接收机获得自身位置信息时,就难以获得有用的交通提示风险服务。提出了一种新的基于车载移动ad-hoc网络车辆定位方法,该方法能够获取作为网络节点车辆的大致位置,并结合一种改进的警报信息优化传播算法,向即将处于危险或拥堵区域的不能通过GPS接收机定位的车辆发送警报信息。仿真实验表明只要车辆自组织网络中有40%的车辆可以获得GPS的定位信息,就可以将警报信息准确完整地送达处于网络中的所有车辆。当遇到浓雾天气、交通事故或者是其他拥塞时,该方法会防止车辆进一步拥堵并能提醒驾驶员防范危险。

  4. Cluster Based Location-Aided Routing Protocol for Large Scale Mobile Ad Hoc Networks

    Science.gov (United States)

    Wang, Yi; Dong, Liang; Liang, Taotao; Yang, Xinyu; Zhang, Deyun

    Routing algorithms with low overhead, stable link and independence of the total number of nodes in the network are essential for the design and operation of the large-scale wireless mobile ad hoc networks (MANET). In this paper, we develop and analyze the Cluster Based Location-Aided Routing Protocol for MANET (C-LAR), a scalable and effective routing algorithm for MANET. C-LAR runs on top of an adaptive cluster cover of the MANET, which can be created and maintained using, for instance, the weight-based distributed algorithm. This algorithm takes into consideration the node degree, mobility, relative distance, battery power and link stability of mobile nodes. The hierarchical structure stabilizes the end-to-end communication paths and improves the networks' scalability such that the routing overhead does not become tremendous in large scale MANET. The clusterheads form a connected virtual backbone in the network, determine the network's topology and stability, and provide an efficient approach to minimizing the flooding traffic during route discovery and speeding up this process as well. Furthermore, it is fascinating and important to investigate how to control the total number of nodes participating in a routing establishment process so as to improve the network layer performance of MANET. C-LAR is to use geographical location information provided by Global Position System to assist routing. The location information of destination node is used to predict a smaller rectangle, isosceles triangle, or circle request zone, which is selected according to the relative location of the source and the destination, that covers the estimated region in which the destination may be located. Thus, instead of searching the route in the entire network blindly, C-LAR confines the route searching space into a much smaller estimated range. Simulation results have shown that C-LAR outperforms other protocols significantly in route set up time, routing overhead, mean delay and packet

  5. A Globally Accessible List (GAL Based Recovery Concept In Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    A.K.Daniel,

    2011-04-01

    Full Text Available A mobile ad-hoc network is a mobile, multi-hop wireless network which is capable of autonomous operation whose primary role is to provide a reliable end to end communication between nodes in the network.However achieving reliable transmission in mobile wireless network is crucial due to change in the network topology caused by node mobility. Modern communication network is becoming increasing & diverse. This is the consequence of an increasing array of devices & services both wired & wireless. There are various protocols to facilitate communication in ad hoc network like DSR and TORA. However these approaches end up in the inefficient utilization of resources after link failure and congestion. This paper proposes an approach to get over this problem .We have added some static nodes which only keeps information related to the current working path and also helps in quick recovery in case of link failure .

  6. Throughput Enhancement Using Multiple Antennas in OFDM-based Ad Hoc Networks under Transceiver Impairments

    CERN Document Server

    Zhao, Pengkai

    2010-01-01

    Transceiver impairments, including phase noise, residual frequency offset, and imperfect channel estimation, significantly affect the performance of Multiple-Input Multiple-Output (MIMO) system. However, these impairments are not well addressed when analyzing the throughput performance of MIMO Ad Hoc networks. In this paper, we present an analytical framework to evaluate the throughput of MIMO OFDM system under the impairments of phase noise, residual frequency offset, and imperfect channel estimation. Using this framework, we evaluate the Maximum Sum Throughput (MST) in Ad Hoc networks by optimizing the power and modulation schemes of each user. Simulations are conducted to demonstrate not only the improvement in the MST from using multiple antennas, but also the loss in the MST due to the transceiver impairments. The proposed analytical framework is further applied for the distributed implementation of MST in Ad Hoc networks, where the loss caused by impairments is also evaluated.

  7. A reliable routing algorithm based on fuzzy Petri net in mobile ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    HU Zhi-gang; MA Hao; WANG Guo-jun; LIAO Lin

    2005-01-01

    A novel reliable routing algorithm in mobile ad hoc networks using fuzzy Petri net with its reasoning mechanism was proposed to increase the reliability during the routing selection. The algorithm allows the structured representation of network topology, which has a fuzzy reasoning mechanism for finding the routing sprouting tree from the source node to the destination node in the mobile ad hoc environment. Finally, by comparing the degree of reliability in the routing sprouting tree, the most reliable route can be computed. The algorithm not only offers the local reliability between each neighboring node, but also provides global reliability for the whole selected route. The algorithm can be applied to most existing on-demand routing protocols, and the simulation results show that the routing reliability is increased by more than 80% when applying the proposed algorithm to the ad hoc on demand distance vector routing protocol.

  8. A Distributed Authentication Algorithm Based on GQ Signature for Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    YAO Jun; ZENG Gui-hua

    2006-01-01

    Identity authentication plays an important role in ad hoc networks as a part of the secure mechanism. On the basis of GQ signature scheme, a new GQ threshold group signature scheme was presented, by which a novel distributed algorithm was proposed to achieve the multi-hop authentication for mobile ad hoc networks. In addition, a protocol verifying the identity with zero knowledge proofs was designed so that the reuse of certificates comes into truth. Moreover, the security of this algorithm was proved through the random oracle model. With the lower cost of computation and communication, this algorithm is efficient, secure and especially suitable for mobile ad hoc networks characterized by distributed computing, dynamic topology and multi-hop communications.

  9. Characterization of biodegradable film based on zein and oleic acid added with nanocarbonate

    Directory of Open Access Journals (Sweden)

    Wanessa Ximenes Ribeiro

    2015-10-01

    Full Text Available Zein oleic acid films added with 1, 2 and 3 % (w/w of nanocarbonate and 30 % glycerol as plasticizer, were produced and evaluated according to their structure and functional properties. Structural characteristics were analyzed by optical and scanning electron microscopy (SEM. Water solubility and mechanical properties were determined according to ASTM methods. The increase of nanocarbonate concentration increased water solubility and influenced the color and mechanical properties. Optical and SEM of film samples added with nanocarbonate, shown low amount of pores and great fat globules size.

  10. Comparative study of Attacks on AODV-based Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Ipsa De

    2011-01-01

    Full Text Available In recent years, the use of mobile ad hoc networks (MANETs has been widespread in many applications, The lack of infrastructures in MANETs makes the detection and control of security hazards allthe more difficult. The security issue is becoming a major concern and bottle neck in the application of MANET. In this paper, an attempt has been made to thoroughly study the blackhole attack which is one ofthe possible attacks in ad hoc networks in routing protocol AODV with possible solution to blackhole attack detection.

  11. A Network Security and Defense Program Based on Ad Hoc%一种基于Ad Hoc的网络安全防御方案

    Institute of Scientific and Technical Information of China (English)

    黄成兵; 陈明东

    2012-01-01

    Analying of Wireless Ad Hoc networks play an important role in society, and its facing a variety of security threats, this paper discusses the advantages and limitations of various network security solutions and technologies for wireless Ad Hoc networks , proposes an in-depth security defense program and explains its implementation process, while points out some of the problems of wireless Ad Hoc networks need to be resolved in the security field.%分析无线Ad Hoc网络在社会中发挥的重要作用及其面临的多种安全威胁,讨论目前各种网络安全解决方案和技术的优点及局限性,提出一种针对无线Ad Hoc网络的纵深安全防御方案并阐述其执行过程,同时指出无线Ad Hoc网络在安全领域急需解决的一些问题.

  12. BPM Analog front-end electronics based on the AD8307 log amplifier

    Science.gov (United States)

    Shurter, R. B.; Gilpatrick, J. D.; Power, J.

    2000-11-01

    Beam position monitor (BPM) signal-processing electronics utilizing the Analog Devices AD8307 logarithmic amplifier has been developed for the Low Energy Demonstration Accelerator (LEDA), part of the Accelerator Production of Tritium (APT) project at Los Alamos. The low-pass filtered 350 MHz fundamental signal from each of the four microstrip electrodes in a BPM is "detected" by an AD8307 log amp, amplified and scaled to accommodate the 0 to +5 V input of an analog-to-digital (A/D) converter. The resultant four digitized signals represent a linear power relationship to the electrode signals, which are in turn related to beam current and position. As the AD8307 has a potential dynamic range of approximately 92 dB, much attention must be given to noise reduction, sources of which can be digital signals on the same board, power supplies, inter-channel coupling, stray RF and others. This paper will describe the operational experience of this particular analog front-end electronic circuit design.

  13. BPM ANALOG FRONT-END ELECTRONICS BASED ON THE AD8307 LOG AMPLIFIER

    Energy Technology Data Exchange (ETDEWEB)

    R. SHURTER; ET AL

    2000-06-01

    Beam position monitor (BPM) signal-processing electronics utilizing the Analog Devices AD8307 logarithmic amplifier has been developed for the Low Energy Demonstration Accelerator (LEDA), part of the Accelerator Production of Tritium (APT) project at Los Alamos. The low-pass filtered 350 MHz fundamental signal from each of the four microstrip electrodes in a BPM is ''detected'' by an AD8307 log amp, amplified and scaled to accommodate the 0 to +5V input of an analog-to-digital (A/D) converter. The resultant four digitized signals represent a linear power relationship to the electrode signals, which are in turn related to beam current and position. As the AD8307 has a potential dynamic range of approximately 92 dB, much attention must be given to noise reduction, sources of which can be digital signals on the same board, power supplies, inter-channel coupling, stray RF and others. This paper will describe the operational experience of this particular analog front-end electronic circuit design.

  14. Tailoring the Implementation of New Biomarkers Based on Their Added Predictive Value in Subgroups of Individuals

    NARCIS (Netherlands)

    van Giessen, A.; Moons, K.G.M.; de Wit, G.A.; Verschuren, W.M.M.; Boer, J.M.A.; Koffijberg, Hendrik

    2015-01-01

    Background The value of new biomarkers or imaging tests, when added to a prediction model, is currently evaluated using reclassification measures, such as the net reclassification improvement (NRI). However, these measures only provide an estimate of improved reclassification at population level. We

  15. Tailoring the Implementation of New Biomarkers Based on Their Added Predictive Value in Subgroups of Individuals

    NARCIS (Netherlands)

    Giessen, van A.; Moons, K.G.M.; Wit, de G.A.; Verschuren, W.M.M.; Boer, J.M.A.; Koffijberg, H.

    2015-01-01

    Background The value of new biomarkers or imaging tests, when added to a prediction model, is currently evaluated using reclassification measures, such as the net reclassification improvement (NRI). However, these measures only provide an estimate of improved reclassification at population level. We

  16. New grid based test bed environment for carrying out ad-hoc networking experiments

    CSIR Research Space (South Africa)

    Johnson, D

    2006-09-01

    Full Text Available and the third is to do analysis on a real test bed network which has implemented the ad-hoc networking protocol. This paper concerns the third option. Most researchers who have done work on test bed environments have used either indoor Wifi inter-office links...

  17. Disentangling location-based advertising : the effects of location congruency and medium type on consumers' ad attention and brand choice

    NARCIS (Netherlands)

    Ketelaar, Paul; Bernritter, Stefan; van 't Riet, Jonathan; Huhn, Arief Ernst; van Woudenberg, Thabo; Muller, Barbara; Janssen, Loes

    2015-01-01

    Research on location-based advertising (LBA) suggests that the merits of LBA lie in the fact that consumers can be targeted with location-congruent ads on their personal mobile devices. However, LBA consists of two underlying constructs: a mobile (vs. point-of-sales) advertising medium and location

  18. Disentangling location-based advertising : the effects of location congruency and medium type on consumers' ad attention and brand choice

    NARCIS (Netherlands)

    Ketelaar, Paul; Bernritter, Stefan; van 't Riet, Jonathan; Huhn, Arief Ernst; van Woudenberg, Thabo; Muller, Barbara; Janssen, Loes

    2017-01-01

    Research on location-based advertising (LBA) suggests that the merits of LBA lie in the fact that consumers can be targeted with location-congruent ads on their personal mobile devices. However, LBA consists of two underlying constructs: a mobile (vs. point-of-sales) advertising medium and location

  19. Context sensitive trust based geographic opportunistic routing in mobile ad hoc networks

    Indian Academy of Sciences (India)

    A RAJESH; N MOHAN KUMAR

    2016-11-01

    Position based opportunistic routing (POR) is a stateless, robust, and reliable geographic routing protocol in Mobile AdHoc NETwork (MANET). The opportunistic routing embraces broadcast property of wireless channels and utilizes it for opportunistic forwarding. Both the malicious node behavior and the backupnodes’ behavior are equally treated as malicious in the existing misbehavior detection mechanisms. Hence, incorporating a general trust model in POR is not combative with routing attacks. It is necessary to determine whether the misbehavior is likely a result of malicious activity or due to the backup scenario of opportunistic forwarding. On the other hand, if context-sensitive trust information is available on every node, it ensures a fair decision making and also supports secured routing in an opportunistic approach. This work investigates the utilization of context attributes along with generic trust model to allow POR for secure and reliable data forwarding. This paper introduces context-sensitive trust for choosing the data forwarding node in POR (CPOR) to assist opportunistic routing in selecting the trusted optimal data forwarding node and to cope with both security and reliability of communications. The proposed work exercises both coarse- and fine-grained trust evaluation to strengthen the trustworthiness. The coarse-grained trust measure includes positive progress per hop and behavioral attribute of the nodes in terms of routing service. The fine-grained trust evaluation differs the opportunistic routing environment from the adverse scenarios and aids the source node such that it builds a highly trusted positive progress set using contextual attributes. The fine-grained trust evaluation deduces the ideal contextual information such as the link quality, battery energy, and the backup service to determine the accurate trust value of nodes. As a result, it involves optimal routes and enables CPOR to maintain the routingperformance equal to the POR even

  20. Experimental performance study of wireless ad hoc system utilizing 802.11a standard base on different routing protocols

    Science.gov (United States)

    Zhong, Xiao F.; Wang, You-Zheng; Mei, Shunliang; Wang, Jing

    2002-08-01

    The wireless ad hoc network technology provides a flexible infrastructure for next generation mobile telecommunication. In this paper, the performances of the networks based on IEEE802.11a standard, including packets successful delivery rate, average end-to-end delay and system throughput, have been studied with different routing protocols (AODV, WRP, and FISHEYE) using GloMoSim to evaluate the effects of various factors, such as node mobility, node density, and node radio transmission range. The simulation results show that adaptive routing protocol will be more suitable for the variation ad hoc network and the results are helpful for the optimum design and deployment of an actual network.

  1. Sublingual administration of an adenovirus serotype 5 (Ad5)-based vaccine confirms Toll-like receptor agonist activity in the oral cavity and elicits improved mucosal and systemic cell-mediated responses against HIV antigens despite preexisting Ad5 immunity.

    Science.gov (United States)

    Appledorn, Daniel M; Aldhamen, Yasser A; Godbehere, Sarah; Seregin, Sergey S; Amalfitano, Andrea

    2011-01-01

    HIV/AIDS continue to devastate populations worldwide. Recent studies suggest that vaccines that induce beneficial immune responses in the mucosal compartment may improve the efficacy of HIV vaccines. Adenovirus serotype 5 (Ad5)-based vectors remain a promising platform for the development of effective vaccines. In an effort to improve the efficacy of Ad5-based vaccines, even in the presence of preexisting Ad5 immunity, we evaluated the potential for an Ad5-based HIV vaccine to induce antigen-specific immune responses following sublingual (s.l.) administration, a route not previously tested in regard to Ad-based vaccines. s.l. vaccination with an Ad5-based HIV-Gag vaccine resulted in a significant induction of Gag-specific cytotoxic T-lymphocyte (CTL) responses in both the systemic and the mucosal compartment. We also show that s.l. immunization not only avoided preexisting Ad5 immunity but also elicited a broad repertoire of antigen-specific CTL clones. Additionally, we confirm for the first time that oral delivery of a vaccine expressing a potent Toll-like receptor (TLR) agonist can stimulate innate immune responses through induction of cytokines and chemokines and activation of NK cells, NKT cells, and macrophages in vivo. These results positively correlated with improved antigen-specific CTL responses. These results could be achieved both in Ad5-naïve mice and in mice with preexisting immunity to Ad5. The simplicity of the s.l. vaccination regimen coupled with augmentation of TLR-dependent pathways active in the oral cavity makes s.l. delivery a promising method for HIV vaccine development specifically, as well as for many other vaccine applications in general.

  2. A Systematic Design Method for Large-Scale Wireless Ad Hoc Network Protocol Based on Optimization Decomposition Theory

    OpenAIRE

    Chaonong Xu; Chi Zhang; Yongjun Xu; Zhiguang Wang

    2015-01-01

    The idea of network protocol design based on optimization theory has been proposed and used practically in Internet for about 15 years. However, for large-scale wireless ad hoc network, although protocol could be viewed as a recursive solving of a global optimization problem, protocol design is still facing huge challenge because an effective distributed algorithm for solving global optimization problem is still lacking. We solve the problem by putting forward a systematic design method based...

  3. A Simple Battery Aware Gossip Based Sleep Protocol for Densely Deployed Ad-hoc and Sensor Networks

    OpenAIRE

    Shukla, Ashish

    2010-01-01

    Conserving power in mobile ad-hoc and sensor networks is a big challenge. Most of the nodes in these networks, in general, are battery powered, therefore, an efficient power saving protocol is required to extend the lifetime of such networks. A lot of work has been done and several protocols have been proposed to address this problem. Gossip based protocols, which are based on the results of percolation theory, significantly reduce power consumption with very little implementation overhead. H...

  4. Reliable Coverage Area Based Link Expiration Time (LET) Routing Metric for Mobile Ad Hoc Networks

    Science.gov (United States)

    Ahmed, Izhar; Tepe, K. E.; Singh, B. K.

    This paper presents a new routing metric for mobile ad hoc networks. It considers both coverage area as well as link expiration information, which in turn requires position, speed and direction information of nodes in the network. With this new metric, a routing protocol obtains routes that last longer with as few hops as possible. The proposed routing metric is implemented with Ad Hoc On-Demand Distance Vector Routing (AODV) protocol. Thus, the performance of the proposed routing metric is tested against the minimum hop metric of AODV. Simulation results show that the AODV protocol with the new routing metric significantly improves delivery ratio and reduces routing overhead. The delay performance of AODV with the new metric is comparable to its minimum hop metric implementation.

  5. Implement DUMBO as a Network Based on Mobile Ad hoc Network (MANETs

    Directory of Open Access Journals (Sweden)

    2011-10-01

    Full Text Available Nowadays there are a large variety of wireless access networks. One of these networksis Digital Ubiquitous Mobile Broadband OLSR (DUMBO which has been stronglymotivated by the fact that large scale natural disasters can wipe out terrestrialcommunication infrastructure. DUMBO routers can automatically form one or more selfconfiguring,self-healing networks called Mobile Ad hoc Networks (MANET. VehicleAd hoc Network (VANETs is an advanced version of MANETs. VANETs is offered tobe used by network service providers for managing connection to get a high performanceat real time, high bandwidth and high availability in networks such as WLAN, UMTS,Wi-MAX and etc. In this paper surveying DUMBONET Routers with relevant algorithm,approaches and solutions from the literature, will be consider.

  6. SECURITY IN VEHICULAR AD HOC NETWORK BASED ON INTRUSION DETECTION SYSTEM

    Directory of Open Access Journals (Sweden)

    Omkar Pattnaik

    2014-01-01

    Full Text Available Implementation of mobile ad hoc networks has eventually captured practically most of the parts of day-to-day life. One variation of such networks represents the Vehicular Ad Hoc Networks (VANETs, widely implemented in order to control day-to-day road traffic. The major concern of VANETs is oriented around providing security to moving vehicles that makes it possible to reduce accidents and traffic jam and moreover to establish communication among different vehicles. In this study, we analyze a number of possible attacks that may pertain to VANETs. Intrusion detection imposes various challenges to efficient implementation of VANETs. To overcome it, several intrusion detection measures have been proposed. The Watchdog technique is one of them. We detail this technique so as to make it convenient to implement it in our future investigations.

  7. Mechanical properties and development of supersolvus heat treated new nickel base superalloy AD730TM

    Directory of Open Access Journals (Sweden)

    Devaux A.

    2014-01-01

    Full Text Available The enhancement of efficiency in power generation gas turbine requires the development of new superalloys capable of withstanding higher temperatures. The development of AD730TM superalloy was achieved to provide to this new cast & wrought (C&W superalloy a higher combination between mechanical properties, microstructural stability and cost than that of other C&W superalloys with a temperature capability up to 750 ∘C. Supersolvus heat-treatment of AD730TM was studied to improve the creep properties of fine grain AD730TM superalloy which were not high enough to reach the foreseen conditions of future power generation gas turbine disks. Firstly, the grain growth was studied to select the supersolvus temperature 1120 ∘C and to obtain a homogeneous coarse grain microstructure. Then, various supersolvus heat-treatments with different cycles were tested and applied on a forged pancake with a section representative of power generation gas turbine disk. The average grain size was evaluated to be close to 200 μm for all heat-treatments. Tensile, creep, fatigue and fatigue crack growth tests were performed to compare the various heat-treatments. FEG-SEM examinations were also realized to discuss the relationships between heat-treatment, intragranular gamma prime precipitation and mechanical properties. Finally, a comparison made with other supersolvus heat treated C&W superalloys shows that AD730TM properties obtained with coarse grain microstructure are at the expected level and enable applications for power generation gas turbine discs.

  8. Added Value-based Approach to Analyze Electronic Commerce and Mobile Commerce Business Models

    OpenAIRE

    Pousttchi, Key; Weizmann, Moritz; Turowski, Klaus

    2003-01-01

    In this contribution we propose to apply the theory of informational added values (IAV) on electronic commerce (EC) and mobile commerce (MC). We state that for the success of electronic and mobile offers it is not sufficient to merely make a conventional offer available with new media. Instead, the use of electronic and mobile communication technology is only remunerative if it results in obtaining distinct supplementary IAV. This depends on the exploitation of certain faculties of the use...

  9. Intrusion Detection System for Mobile Ad - Hoc Network Using Cluster-Based Approach

    Directory of Open Access Journals (Sweden)

    Nisha Dang

    2012-06-01

    Full Text Available Today Mobile Ad-hoc Networks have wide spread use in normal as well as mission critical applications. Mobile ad hoc networks are more likely to be attacked due to lack of infrastructure and no central management. To secure Manets many traditional security solutions like encryption are used but not find to be promising. Intrusion detection system is one of the technologies that provide some goodsecurity solutions. IDS provide monitoring and auditing capabilities to detect any abnormality in security of the system. IDS can be used with clustering algorithms to protect entire cluster from malicious code. Existing clustering algorithms have a drawback of consuming more power and they are associated with routes. The routeestablishment and route renewal affects the clusters and asa consequence, the processing and traffic overhead increases due to instability of clusters. The ad hoc networks are battery and power constraint, and therefore IDS cannot be run on all the nodes. A trusted monitoring node can be deployed to detect and respond against intrusions in time. The proposed simplified clustering scheme has been used to detect intrusions, resulting in high detection rates and low processing and memory overhead irrespective of the routes, connections, traffic types and mobility of nodes inthe network.

  10. Research on Micro-Displacement Capacitance Sensor Based on AD7150%基于AD7150微位移电容传感器的研究

    Institute of Scientific and Technical Information of China (English)

    黄林; 陈向东; 谢宁宁; 李晓钰

    2012-01-01

    The capacitance sample of the micro displacement capacitive sensors was obtained by the integrated chip AD7150. The relevant external circuit which added the filter circuit to enhance the ability of the anti-interference was designed for AD7150 chip. The integrated chip AD7150 was controlled by micro control unit (MCU) to read and write through 12C communication. The measurement result shows that the deviation of capacitance measurements is less than 2.5% when using the different nominal capacitance values under 10 pF. The preliminary experimental result shows that the capacitance increases by increasing the distance between the electrode and the object when the dual interdigital sensor is connected to the circuit. The sensitivity is different in the different increment. With the smaller distance, the sensitivity is larger and the largest sensitivity is 686 fF/mm. The sensitivity distribution in the different increment at different starting points is given, and the factor affecting the capacitance of the sensor is summed up.%利用了集成芯片AD7150完成了对微位移电容传感器的电容采样.对AD7150芯片设计了相应的外接电路,为了增强电路的抗干扰能力,加入相应滤波电路;通过单片机模拟I2C通信方式来进行AD7150的读写控制.测量结果给出了10 pF以下不同标称电容值的电容,误差在2.5%以内.初步实验结果表明,当接入双叉电容传感器探头时,电容值随测量距离的增大而增加;在不同位移量下,传感器的灵敏度不同,距离越近,灵敏度越高,最大灵敏度为686 fF/mm,给出了不同情况下的灵敏度分布,并总结了影响电容传感器工作的电路要点.

  11. EFFECTS OF MAIZE GRAIN ADDED IN A DIET BASED ON ALFALFA HAYLAGE ON THE RATION QUALITY IN WETHER SHEEP

    Directory of Open Access Journals (Sweden)

    Marina Vranić

    2011-06-01

    Full Text Available The objective of this experiment was to study the effects of interactions between alfalfa haylage (AH and maize grain (MG (5 vs. 10 g d-1 kg-1 body weight on ad libitum intake, water intake and dry matter (DM digestibility in wether sheep. The AH and MG contained 534.7 and 915.1g DM kg-1 fresh sample respectively, while crude protein (CP concentration was 141 and 106.0 g kg-1DM. Adding of MG (5 or 10 g kg-1 body weight d-1 into AH based ration resulted in linear increase in diet DM intake (g kg-1 M0,75, linear decrease in water intake (P<0.01 and linear increase in diet DM digestibility (P<0,001. A positive associative response of MG supplementation to AH based ration was observed for DM intake (P<0.001 and DM digestibility (P<0.001. No improvements in DM intake were recorded with 10 g MG added kg-1 body weight d-1 in comparison with 5 g MG added kg-1 body weight d-1.

  12. Design and parameter optimization of a small-scale electron-based ADS for radioactive waste transmutation

    Science.gov (United States)

    Feizi, H.; Ranjbar, A. H.

    2015-05-01

    This paper presents the design and feasibility of an electron-LINAC-based small-scale system (ADS) for nuclear waste transmutation. FLUKA simulations have been performed to evaluate the photoneutron yield in high- Z metallic targets such as silver, tungsten, lead, tantalum and uranium irradiated by electron beams of 20-200MeV. The parameters involved in the photoneutron production mechanism including electron beam energy, target material and target shape have been investigated in order to obtain maximum photoneutron production. The neutron reflectors of the ADS, in particular, beryllium, lead and beryllium oxide (BeO) with various thicknesses have been studied. The results show that a combination of an internal reflector of Pb with a thickness of 3cm and an external reflector of BeO with a thickness of 10cm improves the fluence rate. The photoneutron energy spectrum, photoneutron fluence distribution and heat deposition in the electron target have also been presented. At incident electron beam energy of 155MeV, a neutron source of ˜ 4.6 × 1010 (n/cm2/s/mA) has been achieved, which is highly applicable for using in nuclear waste transmutation. The designed ADS has the ability to transmute ˜ 1.5 × 1022 (atoms/y/mA). The obtained results are promising and could lead to the development of a small-scale ADS based on electron LINAC for radioactive waste transmutation and for numerous applications when employed as a photoneutron source.

  13. FRCA: a fuzzy relevance-based cluster head selection algorithm for wireless mobile ad-hoc sensor networks.

    Science.gov (United States)

    Lee, Chongdeuk; Jeong, Taegwon

    2011-01-01

    Clustering is an important mechanism that efficiently provides information for mobile nodes and improves the processing capacity of routing, bandwidth allocation, and resource management and sharing. Clustering algorithms can be based on such criteria as the battery power of nodes, mobility, network size, distance, speed and direction. Above all, in order to achieve good clustering performance, overhead should be minimized, allowing mobile nodes to join and leave without perturbing the membership of the cluster while preserving current cluster structure as much as possible. This paper proposes a Fuzzy Relevance-based Cluster head selection Algorithm (FRCA) to solve problems found in existing wireless mobile ad hoc sensor networks, such as the node distribution found in dynamic properties due to mobility and flat structures and disturbance of the cluster formation. The proposed mechanism uses fuzzy relevance to select the cluster head for clustering in wireless mobile ad hoc sensor networks. In the simulation implemented on the NS-2 simulator, the proposed FRCA is compared with algorithms such as the Cluster-based Routing Protocol (CBRP), the Weighted-based Adaptive Clustering Algorithm (WACA), and the Scenario-based Clustering Algorithm for Mobile ad hoc networks (SCAM). The simulation results showed that the proposed FRCA achieves better performance than that of the other existing mechanisms.

  14. Climate variability in SE Europe since 1450 AD based on a varved sediment record from Etoliko Lagoon (Western Greece)

    Science.gov (United States)

    Koutsodendris, Andreas; Brauer, Achim; Reed, Jane M.; Plessen, Birgit; Friedrich, Oliver; Hennrich, Barbara; Zacharias, Ierotheos; Pross, Jörg

    2017-03-01

    To achieve deeper understanding of climate variability during the last millennium in SE Europe, we report new sedimentological and paleoecological data from Etoliko Lagoon, Western Greece. The record represents the southernmost annually laminated (i.e., varved) archive from the Balkan Peninsula spanning the Little Ice Age, allowing insights into critical time intervals of climate instability such as during the Maunder and Dalton solar minima. After developing a continuous, ca. 500-year-long varve chronology, high-resolution μ-XRF counts, stable-isotope data measured on ostracod shells, palynological (including pollen and dinoflagellate cysts), and diatom data are used to decipher the season-specific climate and ecosystem evolution at Etoliko Lagoon since 1450 AD. Our results show that the Etoliko varve record became more sensitive to climate change from 1740 AD onwards. We attribute this shift to the enhancement of primary productivity within the lagoon, which is documented by an up to threefold increase in varve thickness. This marked change in the lagoon's ecosystem was caused by: (i) increased terrestrial input of nutrients, (ii) a closer connection to the sea and human eutrophication particularly from 1850 AD onwards, and (iii) increasing summer temperatures. Integration of our data with those of previously published paleolake sediment records, tree-ring-based precipitation reconstructions, simulations of atmospheric circulation and instrumental precipitation data suggests that wet conditions in winter prevailed during 1740-1790 AD, whereas dry winters marked the periods 1790-1830 AD (Dalton Minimum) and 1830-1930 AD, the latter being sporadically interrupted by wet winters. This variability in precipitation can be explained by shifts in the large-scale atmospheric circulation patterns over the European continent that affected the Balkan Peninsula (e.g., North Atlantic Oscillation). The transition between dry and wet phases at Etoliko points to longitudinal

  15. 基于ADS-B最小安全间隔评估研究%Research of Minimum Flight Safety Interval Evaluation Based on ADS-B

    Institute of Scientific and Technical Information of China (English)

    李平; 傅强

    2013-01-01

    本文以广播自动监视技术(ADS-B)为主导,从监视系统的监视精度、作用范围和安全间隔入手,采用改进型Reich模型为基础,建立碰撞区和临近区、模型的延迟误差区、航迹固有偏差区的综合模型,结合国际民航组织的飞行安全指标,进行综合概率评估.进一步缩小ADS-B的碰撞最小飞行安全间隔,最后整合尾流安全区,进行航路流量预测.

  16. 基于AD8302的瞬时测频接收机%IFM Receiver Based on AD8302

    Institute of Scientific and Technical Information of China (English)

    唐志凯; 李卫林; 张广辉; 魏铭

    2009-01-01

    为了简化瞬时测频(IFM)接收机的结构、提高集成度,设计了采用AD8302为核心的IFM接收机,并分析了该测频接收机的灵敏度、动态范围、测频精度等关键指标.最后制作了实验系统对该IFM接收机的可行性进行了验证,实验结果表明采用AD8302实现的IFM接收机可以提高测频精度,简化接收机结构.

  17. A Novel Medium Access Control for Ad hoc Networks Based on OFDM System

    Institute of Scientific and Technical Information of China (English)

    YU Yi-fan; YIN Chang-chuan; YUE Guang-xin

    2005-01-01

    Recently, hosts of Medium Access Control (MAC) protocols for Ad hoc radio networks have been proposed to solve the hidden terminal problem and exposed terminal problem. However most of them take into no account the interactions between physical (PHY) system and MAC protocol. Therefore, the current MAC protocols are either inefficient in the networks with mobile nodes and fading channel or difficult in hardware implementation. In this paper, we present a novel media access control for Ad hoc networks that integrates a media access control protocol termed as Dual Busy Tone Multiple Access (DBTMA) into Orthogonal Frequency Division Multiplexing (OFDM) system proposed in IEEE 802.11a standard. The analysis presented in the paper indicates that the proposed MAC scheme achieves performance improvement over IEEE 802.11 protocol about 25%~80% especially in the environment with high mobility and deep fading. The complexity of the proposed scheme is also lower than other implementation of similar busy tone solution. Furthermore, it is compatible with IEEE 802.11a networks.

  18. Performance Analysis of a Cluster-Based MAC Protocol for Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jesús Alonso-Zárate

    2010-01-01

    Full Text Available An analytical model to evaluate the non-saturated performance of the Distributed Queuing Medium Access Control Protocol for Ad Hoc Networks (DQMANs in single-hop networks is presented in this paper. DQMAN is comprised of a spontaneous, temporary, and dynamic clustering mechanism integrated with a near-optimum distributed queuing Medium Access Control (MAC protocol. Clustering is executed in a distributed manner using a mechanism inspired by the Distributed Coordination Function (DCF of the IEEE 802.11. Once a station seizes the channel, it becomes the temporary clusterhead of a spontaneous cluster and it coordinates the peer-to-peer communications between the clustermembers. Within each cluster, a near-optimum distributed queuing MAC protocol is executed. The theoretical performance analysis of DQMAN in single-hop networks under non-saturation conditions is presented in this paper. The approach integrates the analysis of the clustering mechanism into the MAC layer model. Up to the knowledge of the authors, this approach is novel in the literature. In addition, the performance of an ad hoc network using DQMAN is compared to that obtained when using the DCF of the IEEE 802.11, as a benchmark reference.

  19. Development of a bioimpedance spectrometer based on AD8302%基于AD8302的生物阻抗频谱测量仪的研制

    Institute of Scientific and Technical Information of China (English)

    杨宇祥; 王珏; 牛飞龙; 汪宏武

    2006-01-01

    对正弦信号幅值和相位的准确检测是生物阻抗频谱测量中的关键和难点.AD8302是AD公司首款可同时测量两输入信号之间幅度比和相位差的单片集成芯片.本文针对目前生物阻抗频谱测量中的难点,设计了一种基于AD8302的便携式生物阻抗频谱测量仪.文中详细介绍了AD8302的特点和具体的电路设计方法.实测结果表明:在20kHz~1MHz的频率范围内,阻抗幅值的相对误差小于0.36%,相位的绝对误差小于0.26°,实现了生物阻抗频谱的准确测量.

  20. The Conception of the Value-Oriented Controlling Based on the Criterion of Economic Value Added (EVA®

    Directory of Open Access Journals (Sweden)

    Makarenko Tetiana Yu.

    2017-03-01

    Full Text Available This article is aimed at studying the theoretical foundations and elaborating practical recommendations on introduction of the system of value-oriented controlling in the enterprise, using the common in practice conception of economic value added (EVA®. Approaches to calculation and directions for securing growth of the value of economic value added have been defined. Expedience of building a value-oriented controlling system based on this criterion has been substantiated. A regression analysis has been carried out, existence of a relationship between the market value and the value of the indicator of economic value added has been proved. A classification of the accounting adjustments when calculating the indicator values has been provided, allowing to reflect the actual performance and to minimize the disadvantages of the economic value added as an accounting indicator of effectiveness. Proposals to providing by enterprises the value-oriented reporting have been elaborated, which will help transforming the opportunities and prospects for growth in the real value by improving communications with investors and minimizing the information asymmetry between company and participants in the capital markets.

  1. 基于AD73360电力谐波表准确度途径研究%Research of Power Harmonic Instrument Accuracy Based on AD73360

    Institute of Scientific and Technical Information of China (English)

    沈小青; 席震东; 孙朝斌; 石明华; 邱斌

    2012-01-01

    16 -bit A/D converter AD73360 and high -performance digital signal processor TMS320F2812 as the core design of power harmonic instrument is more widely used as an engineering application. Engineering applications to improve accuracy is a key factor in successful implementation. Article gives the block diagram of hardware design. The A/D converter error is basically eliminated by correcting . the AD73360 frequency response. The non-synchronous sampling error is reduced by shifting the phase difference time-domain correction method. All these greatly improve the measurement accuracy, and article gives the MATLAB simulation source code. Experimental results show that the frequency response correction technology, reducing the non-synchronous error and signal conditioning technology improve the measurement accuracy. The instrument accuracy meets GB/T19862-2005 "General requirements for monitoring equipments of power quality" 5. 2. 2 accuracy requirements.%以16位A/D转换器AD73360和高性能数字信号处理器TMS320F2812为核心的电力谐波表设计较为广泛,作为工程应用,提高准确度是工程应用成功实现的关键因素;文章给出了硬件设计框图,通过修正AD73360频率响应,基本消除了A/D转换器引入的误差,通过时域平移相位差校正法,减少非同步采样引入的误差,大大提高了测量准确度;同时给出了MATLAB仿真源代码;实验结果表明,设计中采取的频响修正技术、减小非同步误差技术以及信号调理技术提高了测量准确度,仪表的准确度满足GB/T19862-2005《电能质量监测设备通用要求》5.2.2准确度要求.

  2. Ad Libitum

    Index Scriptorium Estoniae

    2001-01-01

    20. mai. Segakoor Ad Libitum laulis Niguliste Muuseum-kontserdisaalis. Dirigendid Alice Pehk ja Kaie Viigipuu. Kaastegev Tiit Kiik (orel). Esitati koorimuusikat renessansist tänapäevani ning prantsuse orelimuusikat : [täistekst

  3. 基于 MIMO 技术和“双环”技术的 Ad Hoc 网络路由协议%Ad Hoc network routing protocol based on MIMO technology and double loop technology

    Institute of Scientific and Technical Information of China (English)

    李艳霞

    2014-01-01

    According to the drawbacks of previous Ad Hoc network , this paper puts forward Ad Hoc network routing protocol based on MIMO technology and double loop technology .Under the support of MIMO technology and double loop technology , the new Ad Hoc net-work routing protocol adopts diversity link and reuse link to give play to the advantage of DZR protocol and ZRP protocol .With OPNET simulation as the platform, it is optimized.%针对以往的 Ad Hoc 网络的缺陷,提出了一种基于 MIMO 技术和“双环”技术的 Ad Hoc 网络路由协议方案。在MIMO 技术、“双环”技术的支持下,新的 Ad Hoc 网络路由协议中采用了分集链路与复用链路,发挥了 DZR 协议与 ZRP协议的优势,以 OPNET 仿真工具为平台,从而实现了新 Ad Hoc 网络路由协议的最优化。

  4. Intrusion Detection In Mobile Ad Hoc Networks Using GA Based Feature Selection

    CERN Document Server

    Nallusamy, R; Duraiswamy, K

    2009-01-01

    Mobile ad hoc networking (MANET) has become an exciting and important technology in recent years because of the rapid proliferation of wireless devices. MANETs are highly vulnerable to attacks due to the open medium, dynamically changing network topology and lack of centralized monitoring point. It is important to search new architecture and mechanisms to protect the wireless networks and mobile computing application. IDS analyze the network activities by means of audit data and use patterns of well-known attacks or normal profile to detect potential attacks. There are two methods to analyze: misuse detection and anomaly detection. Misuse detection is not effective against unknown attacks and therefore, anomaly detection method is used. In this approach, the audit data is collected from each mobile node after simulating the attack and compared with the normal behavior of the system. If there is any deviation from normal behavior then the event is considered as an attack. Some of the features of collected audi...

  5. Enhanced Partial Dominant Pruning (EPDP Based Broadcasting in Ad hoc Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ashikur Rahman

    2009-11-01

    Full Text Available In many applications of ad-hoc wireless networks, one often has to broadcast the same message to all nodes. The major goal of any broadcasting algorithm is to minimize the number of retransmissions, i.e., to accomplish the goal with the minimum amount of traffic in the network. In addition to reducing the bandwidth expense needed to convey the message to all the nodes, this objective will try to minimize the total amount of energy spent by the nodes on this communal task. This is of paramount importance in sensor networks, which are often built of disposable nodes, whose life-time is directly determined by the efficiency of their power management scheme. In this paper, we present a heuristic broadcast algorithm dubbed EPDP, for Enhanced Partial Dominant Pruning, and demonstrate its superiority, in terms of the total number of retransmissions, over other solutions addressing the same issue.

  6. COLLABORATIVE ANOMALY-BASED INTRUSION DETECTION IN MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    SUNIL K. PARYANI,

    2011-05-01

    Full Text Available Intrusion Prevention is first line of defense against attacks in MANET. Intrusion Detection and response presents a second line of defense. New vulnerabilities will continue to invent new attack methods so new technology such as MANET, we focus on developing effective detection approaches In this paper, we present an intrusion detection system for detection of malicious node in mobile ad hoc network. The technique is designed for detection of malicious nodes in a neighborhood in which each pair of nodes are within radio range of each other. Such a neighborhood of nodes is known as a clique. [1] This technique is aimed to reduce the computation and communication costs to select a monitor node and reduces the message passing between the nodes to detect a malicious node from the cluster hence there very less traffic and less chances of a collision.

  7. 基于AD5933的便携式阻抗仪研制%Development of Portable Impedance Meter Based on AD5933

    Institute of Scientific and Technical Information of China (English)

    温新华; 颜小飞; 安冬

    2013-01-01

    阻抗测试芯片AD5933高度集成化、低成本的特点使其具有解决市场上阻抗仪体积大、成本昂贵等问题的潜力;在分析AD5933存在问题的基础上,研制了基于AD5933的便携式阻抗仪;系统采用S3C2440AL ARM9处理器为控制核心,通过I2C接口控制阻抗测量模块完成测量,并通过触摸屏显示测量结果;硬件上通过设计信号调理电路消除直流分量及输出阻抗的影响,软件上采用全新的校准方法实现阻抗计算以减小存储量及查询量;阻抗测量实验表明,所设计阻抗仪的阻抗模值平均相对误差为0.33%,最大相位误差为4°,满足一般阻抗测量要求;该阻抗仪还具有操作简单、成本低、体积小的优点.

  8. Finger galvanometer based on instrumentation amplifier AD620%基于仪表放大器AD620的指针检流计

    Institute of Scientific and Technical Information of China (English)

    董善许

    2011-01-01

    本文论述了基于仪表放大器AD620和6脚PIC单片机的指针检流计的设计.解决了目前指针检流计容易出现漂移的问题.采用2节5号电池供电并利用单片机进行功耗管理,有效地降低了检流计的电池使用成本.

  9. A personnel information transmission system based on Ad Hoc networks%基于Ad Hoc网络的人员信息无线传输系统

    Institute of Scientific and Technical Information of China (English)

    汪莹; 刘海立; 王庆辉; 封岸松

    2015-01-01

    A real⁃time information transmission system for the fire firefighters was designed according to the network nodes of the fire fighters moving in fire scene. In the design,MEMS inertial components and sensor network are used to collect data, the data transmission and communication between hardwares are completed by 433 MHz wireless network. The communication between network and monitoring center is realized by means of Ad Hoc wireless networks. The feasibility of the system applied to fire rescue was verified by the experimental and testing results. It can provide further safeguard for the life security of firefighters.%以火灾现场内部消防队员作移动的网络节点设计了一个消防队员实时信息传输系统。设计中用传感器网络和MEMS惯性器件进行数据收集,通过433 MHz 无线网络完成硬件之间的数据传输通信,网络节点与监控中心的通信使用Ad Hoc无线网络完成。实验测试结果验证了该系统应用于消防救援的可行性,为救援队员的生命安全提供了进一步保障。

  10. Based on the AD9850 signal generator design%基于AD9850的信号发生器的设计

    Institute of Scientific and Technical Information of China (English)

    祝敏; 曾德志; 廖小新

    2007-01-01

    直接数字合成(DDS)是一种重要的频率合成技术,具有分辨率高、频率变换快等优点,在雷达及通信等领域有着广泛的应用前景.系统采用AD9850(DDS)与AT89S52单片机相结合的方法,以AD9850为频率合成器,以单片机为进程控制和任务调度的核心,设计了一个信号发生器.实现了输出频率在10Hz~1MHz范围可调,输出信号频率稳定度优于10-3的正弦波、方波和三角波信号.正弦波信号的电压峰峰值Vopp能在0~5V范围内步进调节,步进间隔达到0.1V,所有输出信号无明显失真,且带负载能力强.

  11. Simple impedance meter based on AD8302 chip%基于AD8302的简易阻抗测量仪

    Institute of Scientific and Technical Information of China (English)

    任庆芳; 宋智; 薛严冰

    2016-01-01

    针对目前商业化的阻抗分析仪价格昂贵的现状,用双定向耦合器和幅相检测芯片AD8302设计了一款简易的阻抗测量仪.双定向耦合器用来构成反射计电路,分离出输入信号和反射信号;AD8302用来测量两路信号的幅度增益和相位差.将两部分结合后通过测反射系数求得负载阻抗.在75~85 MHz频率范围内测量了贴片电阻的阻抗值,实部的最大相对误差为3.8%,虚部呈现了较小的电抗值.测量结果表明该简易阻抗测量仪可以实现较高频率范围内阻抗的初步测量.

  12. Compact FPGA-based beamformer using oversampled 1-bit A/D converters.

    Science.gov (United States)

    Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2005-05-01

    A compact medical ultrasound beamformer architecture that uses oversampled 1-bit analog-to-digital (A/D) converters is presented. Sparse sample processing is used, as the echo signal for the image lines is reconstructed in 512 equidistant focal points along the line through its in-phase and quadrature components. That information is sufficient for presenting a B-mode image and creating a color flow map. The high sampling rate provides the necessary delay resolution for the focusing. The low channel data width (1-bit) makes it possible to construct a compact beamformer logic. The signal reconstruction is done using finite impulse reponse (FIR) filters, applied on selected bit sequences of the delta-sigma modulator output stream. The approach allows for a multichannel beamformer to fit in a single field programmable gate array (FPGA) device. A 32-channel beamformer is estimated to occupy 50% of the available logic resources in a commercially available mid-range FPGA, and to be able to operate at 129 MHz. Simulation of the architecture at 140 MHz provides images with a dynamic range approaching 60 dB for an excitation frequency of 3 MHz.

  13. Packet Size Based Routing for Stable Data Delivery in Mobile Ad-Hoc Networks

    Science.gov (United States)

    Khan, Ashiq; Suzuki, Toshihiro; Kobayashi, Motonari; Takita, Wataru; Yamazaki, Kenichi

    In Mobile AD-hoc Networks (MANET), transportation capability of wireless links' varies according to the size of the packets they transport. This instability, which is more acute in long links, has received little attention in the stabilizing schemes proposed so far for MANET. A lot of research has been carried out to utilize more reliable links in making end-to-end routes to avoid frequent route failures and realize higher packet delivery ratio. However, these approaches mainly consider the availability of a link over time and depend on link history which is difficult to acquire in highly dynamic systems. In this paper, we present an easy-to-implement but efficient method to find suitable end-to-end routes that are capable of transporting different sizes of the application data packets. Our scheme is stateless and does not rely on the underlying data link and physical layers. An extensive simulation shows the validity of our concept and highlights the improvement achieved by our proposal.

  14. ADDED VALUE-BASED APROACH TO ANALYZE ELECTRONIC COMMERCE AND MOBILE COMMERCE BUSINESS MODELS

    Directory of Open Access Journals (Sweden)

    Moritz Weizmann

    2004-03-01

    Full Text Available

    Se propone aplicar la teoría del valor informacional agregado (Theory of Informational Added Values, IAV al Electronic Commerce (EC y al Mobile Commerce (MC. El trabajo presentado es una propuesta para acercarse a modelos de negocio, con el foco de criterios típicos de evaluación para modelos de negocio de Internet y del MC. Es también conveniente para comparar modelos de negocio distintos y para poner el valor añadido para los participantes en un contexto. De esta manera, se establecen criterios objetivos que reducen la subjetividad y permiten hacer ciertas predicciones. El artículo termina con un análisis crítico del estado del arte y un comentario sobre las perspectivas futuras.

  15. The congestion control algorithm based on queue management of each node in mobile ad hoc networks

    Science.gov (United States)

    Wei, Yifei; Chang, Lin; Wang, Yali; Wang, Gaoping

    2016-12-01

    This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. As the network load increases, local congestion of mobile ad hoc network may lead to network performance degradation, hot node's energy consumption increase even failure. If small energy nodes congested because of forwarding data packets, then when it is used as the source node will cause a lot of packet loss. This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. Controlling nodes buffer queue in different levels of congestion area probability by adjusting the upper limits and lower limits, thus nodes can adjust responsibility of forwarding data packets according to their own situation. The proposed algorithm will slow down the send rate hop by hop along the data package transmission direction from congestion node to source node so that to prevent further congestion from the source node. The simulation results show that, the algorithm can better play the data forwarding ability of strong nodes, protect the weak nodes, can effectively alleviate the network congestion situation.

  16. Study of surfactant-added TMAH for applications in DRIE and wet etching-based micromachining

    Science.gov (United States)

    Tang, B.; Shikida, M.; Sato, K.; Pal, P.; Amakawa, H.; Hida, H.; Fukuzawa, K.

    2010-06-01

    In this paper, etching anisotropy is evaluated for a number of different crystallographic orientations of silicon in a 0.1 vol% Triton-X-100 added 25 wt% tetramethylammonium hydroxide (TMAH) solution using a silicon hemisphere. The research is primarily aimed at developing advanced applications of wet etching in microelectromechanical systems (MEMS). The etching process is carried out at different temperatures in the range of 61-81 °C. The etching results of silicon hemisphere and different shapes of three-dimensional structures in {1 0 0}- and {1 1 0}-Si surfaces are analyzed. Significantly important anisotropy, different from a traditional etchant (e.g. pure KOH and TMAH), is investigated to extend the applications of the wet etching process in silicon bulk micromachining. The similar etching behavior of exact and vicinal {1 1 0} and {1 1 1} planes in TMAH + Triton is utilized selectively to remove the scalloping from deep reactive-ion etching (DRIE) etched profiles. The direct application of the present research is demonstrated by fabricating a cylindrical lens with highly smooth etched surface finish. The smoothness of a micro-lens at different locations is measured qualitatively by a scanning electron microscope and quantitatively by an atomic force microscope. The present paper provides a simple and effective fabrication method of the silicon micro-lens for optical MEMS applications.

  17. 基于Ad hoc网络的一种混合路由算法%Hybrid Routing Algorithm Based on Mobile Ad hoc Network

    Institute of Scientific and Technical Information of China (English)

    徐光伟; 霍佳震; 顾景文; 曹奇英

    2007-01-01

    移动Ad hoc网络中,混合路由协议拥有比先发性(Proactive)和反应性(Reactive)路由协议较好的性能.基于大规模网络中组成员间的连接动态变化而仅有少数成员具有稳定的位置和连接,提出一种混合路由算法.该算法通过改进节点存储结构来优化路由发现时间,理论分析和模拟测试显示该算法具有一定的优势.

  18. AD8302型相位差测量系统的设计%The Design of a System for Measuring the Phase Difference Based on AD8302

    Institute of Scientific and Technical Information of China (English)

    郑珍; 王海; 周渭; 张云华

    2005-01-01

    传统的相位差测量仪需要采用多片中小规模集成电路,不仅电路复杂,测量相位差的精度不高,而且适用的频率范围窄,因此在实际应用中存在着不足之处.本文介绍了用于RF/IF幅度和相位测量的芯片AD8302、一种高速异步FIFO芯片SN74ACT7808和高速A/D芯片TLC5540的性能特性,并利用MCU及上述芯片设计了一种新型的相位差测量系统,给出了该测量系统的接口电路,并阐述了它的实现原理.

  19. Design of Impedance Measurement System Based on AD8302%基于AD8302的阻抗测量系统设计

    Institute of Scientific and Technical Information of China (English)

    牟光红; 李廷军

    2015-01-01

    为了满足宽频、宽量程阻抗测量需求,设计了一种激励源灵活可调的复阻抗测量系统.该系统采用DDS技术提供宽频激励,通过可控参考阻抗电路和AD8302实现阻抗信息提取,提出了一种模拟移相的方法来鉴别相位极性.数据采集和整个系统控制由STM32控制器完成.结果表明:测量系统可在100 Hz~10 MHz工作正常,在宽阻抗范围内具有较高精度.

  20. Lorentzian AdS, Wormholes and Holography

    CERN Document Server

    Arias, Raul E; Silva, Guillermo A

    2011-01-01

    We investigate the structure of two point functions for the QFT dual to an asymptotically Lorentzian AdS-wormhole. The bulk geometry is a solution of 5-dimensional second order Einstein Gauss Bonnet gravity and causally connects two asymptotically AdS space times. We revisit the GKPW prescription for computing two-point correlation functions for dual QFT operators O in Lorentzian signature and we propose to express the bulk fields in terms of the independent boundary values phi_0^\\pm at each of the two asymptotic AdS regions, along the way we exhibit how the ambiguity of normalizable modes in the bulk, related to initial and final states, show up in the computations. The independent boundary values are interpreted as sources for dual operators O^\\pm and we argue that, apart from the possibility of entanglement, there exists a coupling between the degrees of freedom leaving at each boundary. The AdS_(1+1) geometry is also discussed in view of its similar boundary structure. Based on the analysis, we propose a ...

  1. Adding Personality to Gifted Identification: Relationships among Traditional and Personality-Based Constructs

    Science.gov (United States)

    Carman, Carol A.

    2011-01-01

    One of the underutilized tools in gifted identification is personality-based measures. A multiple confirmatory factor analysis was utilized to examine the relationships between traditional identification methods and personality-based measures. The pattern of correlations indicated this model could be measuring two constructs, one related to…

  2. Enhancing Students' Approaches to Learning: The Added Value of Gradually Implementing Case-Based Learning

    Science.gov (United States)

    Baeten, Marlies; Dochy, Filip; Struyven, Katrien

    2013-01-01

    Previous research has shown the difficulty of enhancing students' approaches to learning, in particular the deep approach, through student-centred teaching methods such as problem- and case-based learning. This study investigates whether mixed instructional methods combining case-based learning and lectures have the power to enhance students'…

  3. Transfer Effects of Adding Seductive Details to Case-Based Instruction

    Science.gov (United States)

    Abercrombie, Sara

    2013-01-01

    The current research investigates the efficacy of the case-based instructional method for teacher education when seductive details (i.e. interesting but extraneous details) are included or removed. Aspiring teachers (n = 108) learned about principles of writing effective feedback in a text-based lesson without a description of a classroom case (C…

  4. Organic dopant added polyvinylidene fluoride based solid polymer electrolytes for dye-sensitized solar cells

    Science.gov (United States)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.

    2016-02-01

    The effect of phenothiazine (PTZ) as dopant on PVDF/KI/I2 electrolyte was studied for the fabrication of efficient dye-sensitized solar cell (DSSC). The different weight percentage (wt%) ratios (0, 20, 30, 40 and 50%) of PTZ doped PVDF/KI/I2 electrolyte films were prepared by solution casting method using DMF as a solvent. The following techniques such as Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray diffractometer (XRD) and AC-impedance analysis have been employed to characterize the prepared polymer electrolyte films. The FT-IR studies revealed the complex formation between PVDF/KI/I2 and PTZ. The crystalline and amorphous nature of polymer electrolytes were confirmed by DSC and XRD analysis respectively. The ionic conductivities of polymer electrolyte films were calculated from the AC-impedance analysis. The undoped PVDF/KI/I2 electrolyte exhibited the ionic conductivity of 4.68×10-6 S cm-1 and this value was increased to 7.43×10-5 S cm-1 when PTZ was added to PVDF/KI/I2 electrolyte. On comparison with different wt% ratios, the maximum ionic conductivity was observed for 20% PTZ-PVDF/KI/I2 electrolyte. A DSSC assembled with the optimized wt % of PTZ doped PVDF/KI/I2 electrolyte exhibited a power conversion efficiency of 2.92%, than the undoped PVDF/KI/I2 electrolyte (1.41%) at similar conditions. Hence, the 20% PTZ-PVDF/KI/I2 electrolyte was found to be optimal for DSSC applications.

  5. Communication Interface Design of AD574A Based on Field- Programmable Gates Array%AD574A与现场可编程门阵列的通信接口设计

    Institute of Scientific and Technical Information of China (English)

    占欣然; 徐精华

    2011-01-01

    该设计首先对电力系统谐波测量的要求以及AD574A的特点进行了分析,然后以Altera公司的DE2开发板为平台,实现了AD574A采样电路的硬件设计,同时在QuartusⅡ中完成了AD574A与现场可编程门阵列的接口设计,最后通过程序配置进行了AD采样实验,实验证明了该方法的正确性.%Based on the demand that measurement and control System is low power consumption, high precision and miniaturization, this design has analyzed the requirements of power system harmonic measurement and the characteristics of AD574A at first, then hardware design of sampling circuit is realized with the platform of Altera's DE2 board, and at the same time the interface design of AD574A and Field Programmable Gate Array (abbreviation - the FPGA) is completed in Quartus II, a AD sampling experiment is done under the program configuration at last, the correct ness of the method is proved by experiment.

  6. 基于NS2的Ad Hoc网络路由协议性能对比分析%Performance Comparison and Analysis of Ad Hoc Routing Protocols Based on NS2 Simulations

    Institute of Scientific and Technical Information of China (English)

    高蕾

    2012-01-01

    Mobile Ad Hoc network is a dynamic temporary mobile node self-organizing network. Routing protocols have been the key issues of Ad Hoc network research. Performance comparison and analysis of Ad Hoc routing protocols based on NS2 network simulation software in a number of different situations is carried on. This paper achieves the advantages and disadvantages of different routing protocols in different scene, as well as the right network environment to apply.%移动Ad Hoc网络是移动节点动态临时组建的自组织网络,路由协议一直都是Ad Hoc网络研究的关键问题.使用NS2网络仿真软件,在不同的场景下分析比较移动Ad Hoc网络的5种路由协议DSDV、OLSR、DSR、AODV和TORA性能,得出不同路由协议在不同场景下的优缺点和适用的网络环境.

  7. 基于 ADS1247的小型计量检定铂电阻温度计设计%The Miniature Platinum resistor temperature gauge for Metrology Calibration based on ADS1247r

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    To solve the problem of low precision and complex structure of platinum resistor temperature gauge for metrology calibration in the range of -30-300℃ ,this paper presents a design scheme of miniature platium resistor temperature gauge for metrology calibration based on ADS1247 of TI corp.The programmable constant-current source of ADS1247 is used as exciting source of platinum resistor.The programmable amplifier of ADS1247 is adopted to amplified the voltage drop of platinum resistor during the course of measurement,and the output voltage of amplifier was digitalized by a 24-bit analog-to-digital converter. According to the experiment,the measurement precision of platinum resistor temperature gauge can reach to 0.05℃ ,and the resolution can reach to 0.004℃.%  针对当前在-30-300℃范围内铂电阻计量检定温度计存在结构复杂、精度较低的问题,本文提出一种基于 TI 公司ADS1247的小型计量检定用铂电阻温度计的设计方案。将 ADS1247输出的可编程恒定电流作为铂电阻激励源。测量过程中,采用 ADS1247集成的可编程放大器放大铂电阻的电压降,并将放大器输出信号进行24位的 AD 转换。通过实验测试,基于ADS1247的铂电阻温度计精度可达到0.05℃,分辨率可达到0.004℃。

  8. Research on Cluster-based Key Management Mechanism for Ad Hoc Networks%基于簇的Ad Hoc网络密钥管理机制研究

    Institute of Scientific and Technical Information of China (English)

    王新颖; 吴钊; 王毅

    2011-01-01

    Ad Hoc networks can quickly put up a wireless mobile communication network without conventional network infrastructures. However, its flexible characteristics make security a challenge. Key management is central to ensuring privacy protection in Ad Hoc networks. Following the analysis of existing distributed trust model to Ad Hoc networks, this paper proposes an effective key management scheme based on cluster. The scheme achieves two-way authentication between the nodes, with strong capability of anti-counterfeiting attack. The process of key distribution is simple and the overhead of computation and communication is lower. The performance of simulations shows that the scheme is secure and effective; the scheme is suited to the self-organized and resource-constrained features of Ad Hoc networks.%Ad Hoc网络可以不依赖于现有网络基础设施,快速搭建起一个移动通信网络,然而其灵活性又使其安全性面临着严峻的挑战.密钥管理是Ad Hoc网络安全的关键技术,在分析现有的Ad Hoc网络分布式信任方案基础上,提出一种有效的基于簇的密钥管理方案.该方案实现了节点之间的双向认证,具有较强的抗假冒攻击能力,密钥分发过程简单,计算量和通信量都比较小.仿真结果表明,该方案安全高效,适合Ad Hoc网络自组织和资源受限的特点.

  9. A Rapid Transfer Alignment Method for SINS Based on the Added Backward-Forward SINS Resolution and Data Fusion

    Directory of Open Access Journals (Sweden)

    Xixiang Liu

    2013-01-01

    Full Text Available Two viewpoints are given: (1 initial alignment of strapdown inertial navigation system (SINS can be fulfilled with a set of inertial sensor data; (2 estimation time for sensor errors can be shortened by repeated data fusion on the added backward-forward SINS resolution results and the external reference data. Based on the above viewpoints, aiming to estimate gyro bias in a shortened time, a rapid transfer alignment method, without any changes for Kalman filter, is introduced. In this method, inertial sensor data and reference data in one reference data update cycle are stored, and one backward and one forward SINS resolutions are executed. Meanwhile, data fusion is executed when the corresponding resolution ends. With the added backward-forward SINS resolution, in the above mentioned update cycle, the estimating operations for gyro bias are added twice, and the estimation time for it is shortened. In the ship swinging condition, with the “velocity plus yaw” matching, the effectiveness of this method is proved by the simulation.

  10. Performance Evaluation of Joint Path and Spectrum Diversity Based Routing Protocol in Cognitive Radio Ad Hoc Networks under Critical Conditions

    Directory of Open Access Journals (Sweden)

    Zamree Che-Aron

    2015-06-01

    Full Text Available Cognitive Radio (CR technology has been introduced to solve the problems of spectrum underutilization and spectrum scarcity caused by improper spectrum management policies. The main concept of Cognitive Radio Ad Hoc Network (CRAHN is that, in a wireless ad hoc network, the unlicensed users (or Secondary Users (SUs are allowed to access the temporally unused licensed spectrum bands for data communications without harmful interference to the licensed users (or Primary Users (PUs. In CRAHNs, the mobile SUs communicate with each other without the use of any centralized network infrastructure. Routing in CRAHNs is an important task and faces various challenges including PU interference, frequent network topology changes, energy constraint, volatile bandwidth and fragile connectivity. In this study, an attempt is made to evaluate the performance of the Dual Diversity Cognitive Ad-hoc Routing Protocol (D2CARP in CRAHNs under critical conditions, i.e., high node mobility rate and number of PUs. The D2CARP protocol is a joint path and spectrum diversity based routing protocol for CRAHNs. The performance evaluation is conducted through simulation using NS-2 simulator. The performance metrics to be considered include average throughput, percentage of packet loss, average end-to-end delay and average jitter. The simulation results prove that the protocol performance is significantly affected in the networks with high number of PUs and mobility rate, leading to high path failure rate and severe service outages.

  11. A Secure Routing Protocol to Eliminate Integrity, Authentication and Sleep Deprivation Based Threats in Mobile Ad hoc Network

    Directory of Open Access Journals (Sweden)

    Edna E. Nallathambi

    2011-01-01

    Full Text Available Problem statement: Network security in Mobile Ad hoc Network (MANET is a major issue. Some of the attacks such as modification, impersonation, Time To Live (TTL and sleep deprivation are due to misbehaviour of malicious nodes, which disrupts the transmission. Some of the existing security protocols such as ARAN, SAODV and SEAD are basically used to detect and eliminate one or two types of attacks. The major requirement of a secure protocol is to prevent and eliminate many attacks simultaneously which will make the MANETs more secured. Approach: We propose the algorithm that can prevent and also eliminate multiple attacks simultaneously, called MIST algorithm (Modification, Impersonation, Sleep deprivation and TTL attacks. This algorithm is written on Node Transition Probability (NTP based protocol which provides maximum utilization of bandwidth during heavy traffic with less overhead. Thus this has been named MIST NTP. Results: The proposed MIST NTP has been compared with NTP without the MIST algorithm, Authenticated Routing for Ad hoc Networks (ARAN and Ad hoc on Demand Distance Vector (AODV. Extensive packet level simulations show that MIST NTP produces around 10% less end to end delay than ARAN, it even drops 30% fewer packets compared to malicious NTP on an average and around 50-60% fewer packets compared to AODV during multiple attacks. Conclusion: The results ensure that MIST NTP can break the greatest security challenge prevailing in MANETs by securing the MANET against several attacks at once.

  12. Trust Threshold Based Public Key Management in Mobile Ad Hoc Networks

    Science.gov (United States)

    2016-03-05

    used trust mechanism. Many studies used certificate-based public key manage- ent. However, they have brought out practical limitations cluding high...certificate-based public key management hemes cited above expose practical limitations, including eeding a centralized trusted CA [25] , high...ent sociability derived from the trust profile availabl a priori as well as dynamic social behavior measure by the number of nodes that a node

  13. QoS Guarantee for IEEE 802.11a Based Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    YAOZhongbang; CAOZhigang

    2004-01-01

    In this paper, we propose a Distributed scheduling and optimization scheme (DSOQoS) for QoS guarantee in IEEE 802.11a based MANETs. In DSOQoS, for each station, the network layer takes different scheduling actions according to its local channel conditions estimated by the MAC layer, and the MAC layer takes different packet transmission actions based on the network load conditions estimated by the network layer. The optimizations are based on the following information sharing and interaction: traffic types, QoS parameters, network packet timeout periods, and predicted packet transmission periods. We evaluate the scheme under different network loads and different station moving speeds. The simulation results show that DSOQoS can guarantee the QoS requirements in terms of packet delivery ratio, packet delay and delay jitter.

  14. A Trust Based Cross Layer Security Protocol for Mobile Ad hoc Networks

    CERN Document Server

    Rajaram, A

    2009-01-01

    In this paper, we develop a trust based security protocol based on a cross layer approach which attains confidentiality and authentication of packets in both routing and link layers of MANETs. In the first phase of the protocol, we design a trust based packet forwarding scheme for detecting and isolating the malicious nodes using the routing layer information. It uses trust values to favor packet forwarding by maintaining a trust counter for each node. A node is punished or rewarded by decreasing or increasing the trust counter. If the trust counter value falls below a trust threshold, the corresponding intermediate node is marked as malicious. In the next phase of the protocol, we provide link layer security using the CBCX mode of authentication and encryption. By simulation results, we show that the proposed cross layer security protocol achieves high packet delivery ratio while attaining low delay and overhead.

  15. Neutron time-of-flight spectrometer based on HIRFL for studies of spallation reactions related to ADS project

    Institute of Scientific and Technical Information of China (English)

    张苏雅拉吐; 罗飞; 陈志强; 韩瑞; 刘星泉; 林炜平; 刘建立; 石福栋; 任培培; 田国玉

    2015-01-01

    A Neutron Time-of-Flight (NTOF) spectrometer, based at the Heavy Ion Research Facility in Lanzhou (HIRFL) was developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production double-differential cross sections and the available experimental data, a detailed description of the NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established. The comparisons of the test beam neutron spectra with those of GEANT4 simulations are presented.

  16. An Anonymous Authentication Scheme for Mobile Ad Hoc Networks Based on DAA%基于DAA的移动Ad Hoc网络匿名认证方案

    Institute of Scientific and Technical Information of China (English)

    乐康; 张涛; 锁琰; 毛卫星

    2011-01-01

    随着移动Ad hoc网络(MANET)技术的发展,安全问题受到越来越多的关注.认证服务是MANET安全的基础.近年来,研究人员提出了各种MANET的认证方案,但对于开放环境下MANET的匿名性要求考虑较少.本文基于可信计算技术中的直接匿名证明协议(DAA)[1],提出了一种适合于MANET环境的匿名认证方案.在解决MANET无中心认证问题的同时,实现了节点身份的匿名性,增加了签名的可追踪性,并对节点的访问权限进行了划分,能够满足更多应用场合的要求.

  17. An Agent-based Model Simulation of Multiple Collaborating Mobile Ad Hoc Networks (MANET)

    Science.gov (United States)

    2011-06-01

    RESULTS: Agent Learning Profiles Discounted Positive Reinforcement Learning Learning and Forgetting Forgetting is triggered by task conditions that...disable rational and deliberate mental models –forcing the agent to ignore (or forget) routine processes. Positive reinforcement is earned by an...deliberate behavior of agents as rational entities (model-based functions). 6.Experiment with positive reinforcement learning (with incremental gain over

  18. Multipacket Reception in Wireless Ad Hoc Networks Based on CDMA and Polynomial Phase-modulating Sequences

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-dong; Wang Bao-yun; ZHENG Bao-yu

    2004-01-01

    Based on the polynomial phase-modulating sequences algorithm, this paper presents two schemes for the application of CDMA with polynomial phase signals to improve the signal separation performance. Simulation results illustrate the proposed approach have 1~3 dB improvement about signal-to-interference and noise ratio in most environment, compared with the PPS algorithm.

  19. A Simple Battery Aware Gossip Based Sleep Protocol for Densely Deployed Ad-hoc and Sensor Networks

    CERN Document Server

    Shukla, Ashish

    2010-01-01

    Conserving power in mobile ad-hoc and sensor networks is a big challenge. Most of the nodes in these networks, in general, are battery powered, therefore, an efficient power saving protocol is required to extend the lifetime of such networks. A lot of work has been done and several protocols have been proposed to address this problem. Gossip based protocols, which are based on the results of percolation theory, significantly reduce power consumption with very little implementation overhead. However, not much work has been done to make gossiping battery aware. In this paper we introduce a simple gossip based battery aware sleep protocol. The protocol allows low battery nodes to sleep more, therefore, improves overall network lifetime.

  20. Performance Evaluation of Stable Weight-Based on Demand Routing Protocol for Mobile Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Oon C. Hsi

    2009-01-01

    Full Text Available Problem statement: A MANET is an autonomous collection of mobile users that communicate over relatively bandwidth constrained wireless links. Since the nodes are mobile, the network topology may change rapidly and unpredictably over time. Approach: A Stable Weight-based On demand Routing Protocol (SWORP that uses the weight-based route strategy to select a stable route was created by Wang. But SWORP only evaluated in a limited setting of simulation, more simulation parameter have to test with SWORP to evaluate how far this protocol can go on. In this project, SWORP was implemented in simulation environment with two other routing protocols, AODV and DSR. Results: These three protocols were implemented in Network Simulator 2 (NS2 and the performance was compare with performance metrics, end-to-end delay, number of packet drop and packet delivery ratio. Conclusion: As expected, SWORP had outperformed AODV and DSR in the overall routing performance.

  1. A Zone-Based Self-Organized Handover Scheme for Heterogeneous Mobile and Ad Hoc Networks

    OpenAIRE

    Murad Khan; Kijun Han

    2014-01-01

    Uninterrupted internet services are need of the day and their demand will increase in future by manifold. However, providing uninterrupted services under heterogeneous networks environment is a challenging task. One of the major challenges in this regard is the management of handover system between various networks. This paper proposes a handover management scheme by dividing the total coverage area of the base station (BS) or access point (AP) into three different zones (strong, average, and...

  2. Mobility Based Key Management Technique for Multicast Security in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    B. Madhusudhanan

    2015-01-01

    Full Text Available In MANET multicasting, forward and backward secrecy result in increased packet drop rate owing to mobility. Frequent rekeying causes large message overhead which increases energy consumption and end-to-end delay. Particularly, the prevailing group key management techniques cause frequent mobility and disconnections. So there is a need to design a multicast key management technique to overcome these problems. In this paper, we propose the mobility based key management technique for multicast security in MANET. Initially, the nodes are categorized according to their stability index which is estimated based on the link availability and mobility. A multicast tree is constructed such that for every weak node, there is a strong parent node. A session key-based encryption technique is utilized to transmit a multicast data. The rekeying process is performed periodically by the initiator node. The rekeying interval is fixed depending on the node category so that this technique greatly minimizes the rekeying overhead. By simulation results, we show that our proposed approach reduces the packet drop rate and improves the data confidentiality.

  3. Mobility based key management technique for multicast security in mobile ad hoc networks.

    Science.gov (United States)

    Madhusudhanan, B; Chitra, S; Rajan, C

    2015-01-01

    In MANET multicasting, forward and backward secrecy result in increased packet drop rate owing to mobility. Frequent rekeying causes large message overhead which increases energy consumption and end-to-end delay. Particularly, the prevailing group key management techniques cause frequent mobility and disconnections. So there is a need to design a multicast key management technique to overcome these problems. In this paper, we propose the mobility based key management technique for multicast security in MANET. Initially, the nodes are categorized according to their stability index which is estimated based on the link availability and mobility. A multicast tree is constructed such that for every weak node, there is a strong parent node. A session key-based encryption technique is utilized to transmit a multicast data. The rekeying process is performed periodically by the initiator node. The rekeying interval is fixed depending on the node category so that this technique greatly minimizes the rekeying overhead. By simulation results, we show that our proposed approach reduces the packet drop rate and improves the data confidentiality.

  4. Performance Analysis of Observation Based Cooperation Enforcement in Ad Hoc Networks

    CERN Document Server

    Ghandar, Abeer; Fayed, Zaky Taha

    2012-01-01

    Node misbehavior due to selfish or malicious behavior could significantly degrade the performance of MANET because most existing routing protocols in MANET aim to find the most efficient path. Overhearing and reputation based cooperation schemes have been used to detect and isolate the misbehaving nodes as well as to force them to cooperate. Performance analysis has been done for the network traffic using OCEAN over DSR on ns2 while considering the low energy levels for mobile nodes. Throughput, energy level, routing packets and normalized routing overhead are analyzed for OCEAN and normal DSR to show the impact of OCEAN on the overall network performance.

  5. A DUAL RESERVATION CDMA-BASED MAC PROTOCOL WITH POWER CONTROL FOR AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Jia Min; Chen Huimin; Yuan Yuhua

    2007-01-01

    This paper proposes a new multi-channel Medium Access Control (MAC) protocol named as Dual Reservation Code Division Multiple Access (CDMA) based MAC protocol with Power Control (DRCPC). The code channel is divided into common channel, broadcast channel and several data channels. And dynamic power control mechanism is implemented to reduce near-far interference. Compared with IEEE 802.11 Distributed Coordination Function (DCF) protocol, the results show that the proposed mechanism improves the average throughput and limits the transmission delay efficiently.

  6. Design Method Based on Routing Tree for Topology Update in Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    WEI Zheng-xi; ZHANG Hong; WANG Xiao-ling

    2006-01-01

    A design method based on the tree-model structure for topology update is presented. The routing tree of every node in network is built by defining the data structure and is used to save the topology information of neighbor nodes. The node topology update is accomplished by exchanging their routing trees. For saving the precious wireless bandwidth, the routing tree is sparsely shaped before sending by pruning the redundant routing information. Then, the node topology update is implemented by using algorithms of inserting and deleting routing sub-trees.

  7. Adding Concrete Syntax to a Prolog-Based Program Synthesis System

    Science.gov (United States)

    Fischer, Bernd; Visser, Eelco

    2004-01-01

    Program generation and transformation systems work on two language levels, the object-level (i e., the language of the manipulated programs), and the meta-level (i.e., the implementation language of the system itself). The meta-level representations of object-level program fragments are usually built in an essentially syntax-free fashion using the operations provided by the meta-language. However, syntax matters and a large conceptual distance between the two languages makes it difficult to maintain and extend such systems. Here we describe how an existing Prolog-based system can gradually be retrofitted with concrete object-level syntax, thus shrinking this distance.

  8. HISTORIC BUILDING INFORMATION MODELLING – ADDING INTELLIGENCE TO LASER AND IMAGE BASED SURVEYS

    Directory of Open Access Journals (Sweden)

    M. Murphy

    2012-09-01

    Full Text Available Historic Building Information Modelling (HBIM is a novel prototype library of parametric objects based on historic data and a system of cross platform programmes for mapping parametric objects onto a point cloud and image survey data. The HBIM process begins with remote collection of survey data using a terrestrial laser scanner combined with digital photo modelling. The next stage involves the design and construction of a parametric library of objects, which are based on the manuscripts ranging from Vitruvius to 18th century architectural pattern books. In building parametric objects, the problem of file format and exchange of data has been overcome within the BIM ArchiCAD software platform by using geometric descriptive language (GDL. The plotting of parametric objects onto the laser scan surveys as building components to create or form the entire building is the final stage in the reverse engin- eering process. The final HBIM product is the creation of full 3D models including detail behind the object's surface concerning its methods of construction and material make-up. The resultant HBIM can automatically create cut sections, details and schedules in addition to the orthographic projections and 3D models (wire frame or textured.

  9. Historic Building Information Modelling - Adding Intelligence to Laser and Image Based Surveys

    Science.gov (United States)

    Murphy, M.; McGovern, E.; Pavia, S.

    2011-09-01

    Historic Building Information Modelling (HBIM) is a novel prototype library of parametric objects based on historic data and a system of cross platform programmes for mapping parametric objects onto a point cloud and image survey data. The HBIM process begins with remote collection of survey data using a terrestrial laser scanner combined with digital photo modelling. The next stage involves the design and construction of a parametric library of objects, which are based on the manuscripts ranging from Vitruvius to 18th century architectural pattern books. In building parametric objects, the problem of file format and exchange of data has been overcome within the BIM ArchiCAD software platform by using geometric descriptive language (GDL). The plotting of parametric objects onto the laser scan surveys as building components to create or form the entire building is the final stage in the reverse engin- eering process. The final HBIM product is the creation of full 3D models including detail behind the object's surface concerning its methods of construction and material make-up. The resultant HBIM can automatically create cut sections, details and schedules in addition to the orthographic projections and 3D models (wire frame or textured).

  10. Historic Building Information Modelling - Adding intelligence to laser and image based surveys of European classical architecture

    Science.gov (United States)

    Murphy, Maurice; McGovern, Eugene; Pavia, Sara

    2013-02-01

    Historic Building Information Modelling (HBIM) is a novel prototype library of parametric objects, based on historic architectural data and a system of cross platform programmes for mapping parametric objects onto point cloud and image survey data. The HBIM process begins with remote collection of survey data using a terrestrial laser scanner combined with digital photo modelling. The next stage involves the design and construction of a parametric library of objects, which are based on the manuscripts ranging from Vitruvius to 18th century architectural pattern books. In building parametric objects, the problem of file format and exchange of data has been overcome within the BIM ArchiCAD software platform by using geometric descriptive language (GDL). The plotting of parametric objects onto the laser scan surveys as building components to create or form the entire building is the final stage in the reverse engineering process. The final HBIM product is the creation of full 3D models including detail behind the object's surface concerning its methods of construction and material make-up. The resultant HBIM can automatically create cut sections, details and schedules in addition to the orthographic projections and 3D models (wire frame or textured) for both the analysis and conservation of historic objects, structures and environments.

  11. Adding functionality with additive manufacturing: Fabrication of titanium-based antibiotic eluting implants.

    Science.gov (United States)

    Cox, Sophie C; Jamshidi, Parastoo; Eisenstein, Neil M; Webber, Mark A; Hassanin, Hany; Attallah, Moataz M; Shepherd, Duncan E T; Addison, Owen; Grover, Liam M

    2016-07-01

    Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p=0.01) improved the compressive strength (5.8±0.7MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6hour period (additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections.

  12. Adding A Spending Metric To Medicare's Value-Based Purchasing Program Rewarded Low-Quality Hospitals.

    Science.gov (United States)

    Das, Anup; Norton, Edward C; Miller, David C; Ryan, Andrew M; Birkmeyer, John D; Chen, Lena M

    2016-05-01

    In fiscal year 2015 the Centers for Medicare and Medicaid Services expanded its Hospital Value-Based Purchasing program by rewarding or penalizing hospitals for their performance on both spending and quality. This represented a sharp departure from the program's original efforts to incentivize hospitals for quality alone. How this change redistributed hospital bonuses and penalties was unknown. Using data from 2,679 US hospitals that participated in the program in fiscal years 2014 and 2015, we found that the new emphasis on spending rewarded not only low-spending hospitals but some low-quality hospitals as well. Thirty-eight percent of low-spending hospitals received bonuses in fiscal year 2014, compared to 100 percent in fiscal year 2015. However, low-quality hospitals also began to receive bonuses (0 percent in fiscal year 2014 compared to 17 percent in 2015). All high-quality hospitals received bonuses in both years. The Centers for Medicare and Medicaid Services should consider incorporating a minimum quality threshold into the Hospital Value-Based Purchasing program to avoid rewarding low-quality, low-spending hospitals.

  13. 基于AD8369的数字音频广播传输系统的研究与实现%Design of Digital Audio Broadcasting Power Amplifier System Based on AD8369

    Institute of Scientific and Technical Information of China (English)

    陆明莹; 刘石; 王国裕; 张红升

    2012-01-01

    This paper introduces in detail the structure and theory of AD8369,it functions inside as a digitally controlled variable gain amplifier,Digital Audio Broadcasting Transmitting System based on A8369 was designed.The system used digitally controlled variable gain amplifier device AD8369 fills the power amplifier in the original Digital Audio Broadcasting system.It presents the block of the structure of system,the hardware structure,the software flow chart,timing control chart,testing and certification and descripes in detail the operational principle and process of the system.%该文详细地介绍了具有内部可控功能的数字可控增益放大器件AD8369的结构与工作原理,设计了基于AD8369的数字音频广播传输系统。本系统采用的数字可控增益放大器件AD8369填补了原数字音频广播系统中没有输出功放的空白。该文给出了系统的结构框图、硬件结构框图、软件流程图和时序控制图及测试和验证,详细介绍了系统工作的原理和流程。

  14. Two-level Trajectory-Based Routing Protocol for Vehicular Ad Hoc Networks in Freeway and Manhattan Environments

    Directory of Open Access Journals (Sweden)

    Floriano De Rango

    2009-11-01

    Full Text Available This paper focuses on the routing protocol issue in two important environments for Vehicular Ad Hoc Networks (VANET: Manhattan and the Freeway. A novel protocol called Two-level Trajectory Based Routing (TTBR protocol is proposed. Deterministic vehicles movement permits advantage to be taken of the map info to build a specific local trajectory to reach the destination node. However, in order to offer network scalability also a high level cell-based trajectory is applied to have a coarse knowledge of the cell where the destination node is moving. Our proposal needs Peer Servers and Grid subdivision of the space. Simulation results were assessed to show the improvements and scalability offered by TTBR in comparison with other Ad Hoc networks protocols such as AODV and GPSR. Performance Evaluation was evaluated in terms of Normalized Control Overhead and Data Packet Delivery Ratio. TTBR is more performing than AODV for a high speed and high density scenario for both the Manhattan and Freeway scenarios.

  15. Modeling and Simulation of the Tactical Ad-hoc Subnet Based on OPNET Simulating Platform%基于Opnet平台的战术Ad-hoc子网建模仿真

    Institute of Scientific and Technical Information of China (English)

    卢颖; 康凤举; 钟联炯

    2009-01-01

    由于报文到达服从长相关特性,利用能较好描述长相关特性的自相似模型,借助Opnet仿真手段对战术Ad -hoc子网进行了建模及仿真.仿真中自相似流量模型采用的是多重汇聚的ON/OFF过程模型,网络MAC层选用IEEE 802.11协议的DCF接入方式.根据Opnet仿真软件运行结果的分析,最终得出通信量自相似性对战术Ad-hoc子网性能影响很大,网络的各项性能指标如延迟及丢包率随着自相似程度的增加将变得越来越差,这对战术Ad-hoc网络的应用开发、网络规划及优化配置具有一定的参考价值.%The tactical Ad-hoc network based on self-similarity model is studied and the model is developed and implemented in opnet based on the model of assembling of multiple ON/OFF sources model. IEEE 802.11 DCF is adopted for MAC protocol.The results have shown that self-similarity has great influence on Ad-hoc network performance, the higher the self-similar degree,the worse the network performance.Valuable reference for tactical Ad-hoc network application exploration is provided by comparing and analyzing the simulation results of this traffic model.

  16. Policy based Decentralized Group key Security for Mobile Ad-hoc Networks

    Directory of Open Access Journals (Sweden)

    Sugandha Singh

    2010-05-01

    Full Text Available The unique characteristics and constraints of MANET have made the traditional approach to security inadequate. With this view in mind decentralized group key management is taken into consideration. A novel structure of the node is proposed and each entity holds a secret share SSi of each node in cluster is controlled by its cluster head, the policy enforcer decides for the working of intelligent agent, which is assigned to do the management, which allows two or more parties to derive shared key as a function of information associated with the protocol and so no party can predetermine the resulting value. Group membership certificate is used for group authentication and by the use threshold key scheme secret data is transferred. The SSi of each node is calculated by use of Polynomial interpolation and cluster head key by modular arithmetic, and information is carried by the policy based agents named intelligent agents.

  17. Adding value to figures: a web-based European public health information system.

    Science.gov (United States)

    van der Wilk, Eveline A; Verschuuren, Marieke

    2010-01-01

    In 2008 a prototype, web-based system was launched which provided information for different user groups interested in European public health topics. The EUPHIX system contained scientifically sound data, with presentations as well as textual information. The information was structured according to the European Community Health Indicators (ECHI) shortlist. The information included different types of data presentations (tables, interactive graphs and maps), explanatory texts and overviews of the data sources and the literature used. The content was produced by a network of European experts according to a structured, peer-reviewed editorial process. Thus EUPHIX provided an easily accessible, comprehensive, state-of-the-art information source. To ensure that it will continue, financial support will be needed. Co-ownership by the European Commission and the Member States seems an appropriate solution.

  18. Modified Distributed Medium Access Control Algorithm Based on Multi-Packets Reception in Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    ZHENG Qing; YANG Zhen

    2005-01-01

    Based on the Multi-Packet Reception(MPR)capability at the physical layer and the Distributed Coordination Function(DCF)of the IEEE 802.11 MAC protocol,we propose a modified new solution about WAITING mechanism to make full use of the MPR capability in this paper,which is named as modified distributed medium access control algorithm.We describe the details of each step of the algorithm after introducing the WAITING mechanism.Then,we also analyze how the waiting-time affects the throughput performance of the network.The network simulator NS-2 is used to evaluate the throughput performance of the new WAITING algorithm and we compare it with IEEE 802.11 MAC protocol and the old WAITING algorithm.The experimental results show that our new algorithm has the best performance.

  19. DEMAC: A Cluster-Based Topology Control for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Abhishek Majumder

    2010-09-01

    Full Text Available The presence of transient network links, mobility and limited battery power of mobile nodes in MANETs poses a hefty challenge for such networks to scale and perform efficiently when subjected to varying network condition. Most of the topology control algorithms proposed have high control overhead to discover and maintain route from source to destination. They also have very high topology maintenance cost. To minimize routing overhead and topology maintenance cost CBRP (Cluster Based Routing Protocol was developed. It performs better than other approaches in most of the cases. In this paper, an energy and mobility aware clustering approach is presented. The clustering approach is incorporated in a DSR like protocol for routing in MANET to evaluate the performance improvement gained due to clustering using proposed approach. Rate of cluster head changes, throughput of the network, delay and routing overhead is evaluated using NS2. Simulation results reveal that proposed approach has better performance in comparison with CBRP.

  20. A Proximity based Retransmission Scheme for Power Line Ad-hoc LAN

    CERN Document Server

    Singha, Chitta Ranjan

    2010-01-01

    Power line as an alternative for data transmission is being explored, and also being used to a certain extent. But from the data transfer point of view, power line, as a channel is highly dynamic and hence not quite suitable. To convert the office or home wiring system to a Local Area Network (LAN), adaptive changes are to be made to the existing protocols. In this paper, a slotted transmission scheme is suggested, in which usable timeslots are found out by physically sensing the media. Common usable timeslots for the sender-receiver pair are used for communication. But these will not ensure safe packet delivery since packets may be corrupted on the way during propagation from sender to receiver. Therefore, we also suggest a proximity based retransmission scheme where each machine in the LAN, buffers good packet and machines close to the receiver retransmit on receiving a NACK.

  1. A tree-ring based reconstruction of the Atlantic Multidecadal Oscillation since 1567 A.D

    Science.gov (United States)

    Gray, S.T.; Graumlich, L.J.; Betancourt, J.L.; Pederson, G.T.

    2004-01-01

    We present a tree-ring based reconstruction of the Atlantic Multidecadal Oscillation (AMO) which demonstrates that strong, low-frequency (60-100 yr) variability in basin-wide (0-70??N) sea surface temperatures (SSTs) has been a consistent feature of North Atlantic climate for the past five centuries. Intervention analysis of reconstructed AMO indicates that 20th century modes were similar to those in the preceding ???350 yr, and wavelet spectra show robust multidecadal oscillations throughout the reconstruction. Though the exact relationships between low-frequency SST modes, higher frequency (???7-25 yr) atmospheric modes (e.g., North Atlantic Oscillation/Arctic Oscillation), and terrestrial climates must still be resolved, our results confirm that the AMO should be considered in assessments of past and future Northern Hemisphere climates. Copyright 2004 by the American Geophysical Union.

  2. A Proximity based Retransmission Scheme for Power Line Ad-hoc LAN

    Directory of Open Access Journals (Sweden)

    Chitta Ranjan Singha

    2010-12-01

    Full Text Available Power line as an alternative for data transmission is being explored, and also being used to a certainextent. But from the data transfer point of view, power line, as a channel is highly dynamic and hence not quite suitable. To covert the office or home wiring system to a Local Area Network (LAN, adaptive changes are to be made to the existing protocols. In this paper, a slotted transmission scheme is suggested, in which usable timeslots are found out by physically sensing the media. Common usable timeslots for the sender-receiver pair are used for communication. But these will not ensure safe packet delivery since packets may be corrupted on the way during propagation from sender to receiver. Therefore, we also suggest a proximity based retransmission scheme where each machine in the LAN, buffers good packet and machines close to the receiver retransmit on receiving a NACK.

  3. TRUST BASED CLUSTERING AND SECURE ROUTING SCHEME FOR MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    Pushpita Chatterjee

    2009-07-01

    Full Text Available In this paper we present a distributed self-organizing trust based clustering framework for securing adhoc networks. The mobile nodes are vulnerable to security attacks, so ensuring the security of thenetwork is essential. To enhance security, it is important to evaluate the trustworthiness of nodes withoutdepending on central authorities. In our proposal the evidence of trustworthiness is captured in anefficient manner and from broader perspectives including direct interactions with neighbors, observinginteractions of neighbors and through recommendations. Our prediction scheme uses a trust evaluationalgorithm at each node to calculate the direct trust rating normalized as a fuzzy value between zero andone. The evidence theory of Dempster-Shafer [7], [8] used in order to combine the evidences collectedby a clusterhead itself and the recommendations from other neighbor nodes. Moreover, in our scheme wedo not restrict to a single gateway node for inter cluster routing.

  4. Accuracy Assessment of Digital Surface Models Based on WorldView-2 and ADS80 Stereo Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Christian Ginzler

    2012-05-01

    Full Text Available Digital surface models (DSMs are widely used in forest science to model the forest canopy. Stereo pairs of very high resolution satellite and digital aerial images are relatively new and their absolute accuracy for DSM generation is largely unknown. For an assessment of these input data two DSMs based on a WorldView-2 stereo pair and a ADS80 DSM were generated with photogrammetric instruments. Rational polynomial coefficients (RPCs are defining the orientation of the WorldView-2 satellite images, which can be enhanced with ground control points (GCPs. Thus two WorldView-2 DSMs were distinguished: a WorldView-2 RPCs-only DSM and a WorldView-2 GCP-enhanced RPCs DSM. The accuracy of the three DSMs was estimated with GPS measurements, manual stereo-measurements, and airborne laser scanning data (ALS. With GCP-enhanced RPCs the WorldView-2 image orientation could be optimised to a root mean square error (RMSE of 0.56 m in planimetry and 0.32 m in height. This improvement in orientation allowed for a vertical median error of −0.24 m for the WorldView-2 GCP-enhanced RPCs DSM in flat terrain. Overall, the DSM based on ADS80 images showed the highest accuracy of the three models with a median error of 0.08 m over bare ground. As the accuracy of a DSM varies with land cover three classes were distinguished: herb and grass, forests, and artificial areas. The study suggested the ADS80 DSM to best model actual surface height in all three land cover classes, with median errors < 1.1 m. The WorldView-2 GCP-enhanced RPCs model achieved good accuracy, too, with median errors of −0.43 m for the herb and grass vegetation and −0.26 m for artificial areas. Forested areas emerged as the most difficult land cover type for height modelling; still, with median errors of −1.85 m for the WorldView-2 GCP-enhanced RPCs model and −1.12 m for the ADS80 model, the input data sets evaluated here are quite promising for forest canopy modelling.

  5. Adding functionality with additive manufacturing: Fabrication of titanium-based antibiotic eluting implants

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Sophie C. [School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Jamshidi, Parastoo [School of Materials and Metallurgy, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Eisenstein, Neil M. [School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Royal Centre for Defence Medicine, Birmingham Research Park, Vincent Drive, Edgbaston B15 2SQ (United Kingdom); Webber, Mark A. [School of Biosciences, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Hassanin, Hany [School of Materials and Metallurgy, University of Birmingham, Edgbaston B15 2TT (United Kingdom); School of Mechanical and Automotive Engineering, Kingston University, London SW15 3DW (United Kingdom); Attallah, Moataz M. [School of Materials and Metallurgy, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Shepherd, Duncan E.T. [Department of Mechanical Engineering, School of Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Addison, Owen [School of Dentistry, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Grover, Liam M. [School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom)

    2016-07-01

    Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p = 0.01) improved the compressive strength (5.8 ± 0.7 MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6 hour period (< 28% of the total amount) were found to exceed the minimum inhibitory concentrations of Staphylococcus aureus (16 μg/mL) and Staphylococcus epidermidis (1 μg/mL); two bacterial species commonly associated with periprosthetic infections. Antibacterial efficacy was confirmed against both bacterial cultures using an agar diffusion assay. Interestingly, pore channel orientation was shown to influence the directionality of inhibition zones. Promisingly, this work demonstrates the potential to additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections. - Highlights: • Titanium implants were additively manufactured with surface connected reservoirs. • Implants

  6. Self-Organized Public-Key Management for Mobile Ad Hoc Networks Based on a Bidirectional Trust Model

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In traditional networks ,the authentication is performed by certificate authoritys(CA),which can't be built in distributed mobile Ad Hoc Networks however. In this paper, we propose a fully self-organized public key management based on bidirectional trust model without any centralized authority that allows users to generate their public-private key pairs, to issue certificates, and the trust relation spreads rationally according to the truly human relations. In contrast with the traditional self-organized public-key management, the average certificates paths get more short,the authentication passing rate gets more high and the most important is that the bidirectional trust based model satisfys the trust requirement of hosts better.

  7. Efficient Cluster Based Multicast Tree for Secure Multicast Communication for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    D.Suganya Devi

    2010-05-01

    Full Text Available Secure multicast communication in mobile adhoc networks is challenging due to its inherent characteristics of infrastructure-less architecture with lack of central authority, limited resources such as bandwidth, time and power. Hence key management is the fundamental challenge in achieving secure communication using multicast key distribution in mobile adhoc networks. In many multicast interactions, due to its frequent node mobility, new member can join and current members can leave at a time due to node failure which causes delay in multicast transmission. This paper proposes a new efficient cluster based multicast tree (CBMT algorithm for secure multicast Communication, in which source node uses Multicast version of Destination Sequenced Distance Vector(MDSDV routing protocol to collects its 1 hop neighbors to form cluster and each node which have child node is elected as the Local controllers of the created clusters. It also tolerates the faults that causes due to failure of nodes. Simulation results shows the demonstration of CBMT using MDSDV have better system performance in terms of end to end delay and fault tolerance rate under varying network conditions.

  8. Partial characterization of chayotextle starch-based films added with ascorbic acid encapsulated in resistant starch.

    Science.gov (United States)

    Martínez-Ortiz, Miguel A; Vargas-Torres, Apolonio; Román-Gutiérrez, Alma D; Chavarría-Hernández, Norberto; Zamudio-Flores, Paul B; Meza-Nieto, Martín; Palma-Rodríguez, Heidi M

    2017-05-01

    Chayotextle starch was modified by subjecting it to a dual treatment with acid and heating-cooling cycles. This caused a decrease in the content of amylose, which showed values of 30.22%, 4.80%, 3.27% and 3.57% for native chayotextle starch (NCS), starch modified by acid hydrolysis (CMS), and CMS with one (CMS1AC) and three autoclave cycles (CMS3AC), respectively. The percentage of crystallinity showed an increase of 36.9%-62% for NCS and CMS3AC. The highest content of resistant starch (RS) was observed in CMS3AC (37.05%). The microcapsules were made with CMS3AC due to its higher RS content; the total content of ascorbic acid of the microcapsules was 82.3%. The addition of different concentrations of CMS3AC microcapsules (0%, 2.5%, 6.255% and 12.5%) to chayotextle starch-based films (CSF) increased their tensile strength and elastic modulus. The content of ascorbic acid and RS in CSF was ranged from 0% to 59.4% and from 4.84% to 37.05% in the control film and in the film mixed with CMS3AC microcapsules, respectively. Water vapor permeability (WVP) values decreased with increasing concentrations of microcapsules in the films. Microscopy observations showed that higher concentrations of microcapsules caused agglomerations due their poor distribution in the matrix of the films. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Added transmission capacity in VLC systems using white RGB based LEDs and WDM devices

    Science.gov (United States)

    Louro, P.; Silva, V.; Costa, J.; Vieira, M. A.; Vieira, M.

    2016-04-01

    In this paper an integrated wavelength optical filter and photodetector working as a DEMUX device is used to detect modulated optical signals of visible wavelengths for Visible Light Communication (VLC). The proposed application demonstrates the viability of indoors positioning using VLC technology established by the modulation of indoor warm light lamps lighting with ultra-bright white tri-cromatic LEDs. The signals were transmitted into free space and the generated photocurrent was measured by a pin-pin photodetector based on a-SiC:H/a-Si:H. This device operates in the visible spectrum, allowing thus the detection of the pulsed light emitted by the modulated chips of the white RGB LEDs. However, as the device works also as a visible optical filter with controlled wavelength sensitivity through the use of adequate optical biasing light, it is able to detect different wavelengths, turning it into a DEMUX device. This feature allows the detection of the individual components of the tri-chromatic white LED and is the basis for the indoors location algorithm. We demonstrate the possibility of decoding four transmission optical channels supplied by two different wavelength LEDs modulated under different bit sequences, which allows the location identification and indoor navigation.

  10. Unmanned Aerial ad Hoc Networks: Simulation-Based Evaluation of Entity Mobility Models’ Impact on Routing Performance

    Directory of Open Access Journals (Sweden)

    Jean-Daniel Medjo Me Biomo

    2015-06-01

    Full Text Available An unmanned aerial ad hoc network (UAANET is a special type of mobile ad hoc network (MANET. For these networks, researchers rely mostly on simulations to evaluate their proposed networking protocols. Hence, it is of great importance that the simulation environment of a UAANET replicates as much as possible the reality of UAVs. One major component of that environment is the movement pattern of the UAVs. This means that the mobility model used in simulations has to be thoroughly understood in terms of its impact on the performance of the network. In this paper, we investigate how mobility models affect the performance of UAANET in simulations in order to come up with conclusions/recommendations that provide a benchmark for future UAANET simulations. To that end, we first propose a few metrics to evaluate the mobility models. Then, we present five random entity mobility models that allow nodes to move almost freely and independently from one another and evaluate four carefully-chosen MANET/UAANET routing protocols: ad hoc on-demand distance vector (AODV, optimized link state routing (OLSR, reactive-geographic hybrid routing (RGR and geographic routing protocol (GRP. In addition, flooding is also evaluated. The results show a wide variation of the protocol performance over different mobility models. These performance differences can be explained by the mobility model characteristics, and we discuss these effects. The results of our analysis show that: (i the enhanced Gauss–Markov (EGM mobility model is best suited for UAANET; (ii OLSR, a table-driven proactive routing protocol, and GRP, a position-based geographic protocol, are the protocols most sensitive to the change of mobility models; (iii RGR, a reactive-geographic hybrid routing protocol, is best suited for UAANET.

  11. A Fast Handover Scheme for Multicasting in IPv6 based Mobile Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    H. Parveen Sultana

    2011-01-01

    Full Text Available Abstract: Problem statement: In the previous researches, steps were taken to resolve the problems of multicasting, after several discussions. Actually these issues were raised, while multicasting packets from Internet Protocol (IP to Mobile Nodes (MN. On the other hand, there is very little concern about the problem of packet loss reduction. Sometimes the occurrence of multicast service chaos is ignored during handovers. Therefore in this study it has been tried to explain the optimal multicast technique for Mobile IPv6 (MIPv6 to diminish the required amendment to the existing fast handover. Approach: An alternate method is suggested in Fast handover for MIPv6 (FMIPv6 to lessen the packet losses during handovers, before tunneling. Based on the qualities of the multicast subscription techniques for the Mobile IPv6 (MIPv6, multicast upholds method for FMIPv6. MIPv6 in general comprise two types of multicasting techniques, which are related to Home Agent (HA and Foreign Agent (FA. These techniques help the MN to obtain the packets in roaming location referred as Foreign Network (FN, which is being forwarded by the Core Network (CN. But due to the handover latency problem MN have to experience packet loss while switching between any two Access Routers (AR. A protocol has been designed to conquer the issue of packet loss in MIPv6. Results and Conclusion: This protocol can be used during joining process in MIPv6 before tunneling to eliminate the IP connectivity time. This implementation allows a mobile node to be connected more quickly at a fresh point of connection, when that mobile node moves with less packet losses.

  12. Optimization of Fenton oxidation pre-treatment for B. thuringiensis - based production of value added products from wastewater sludge.

    Science.gov (United States)

    Pham, T T H; Brar, S K; Tyagi, R D; Surampalli, R Y

    2010-08-01

    Fenton oxidation pretreatment was investigated for enhancement of biodegradability of wastewater sludge (WWS) which was subsequently used as substrate for the production of value- added products. The Response surface method with fractional factorial and central composite designs was applied to determine the effects of Fenton parameters on solubilization and biodegradability of sludge and the optimization of the Fenton process. Maximum solubilization and biodegradability were obtained as 70% and 74%, respectively at the optimal conditions: 0.01 ml H(2)O(2)/g SS, 150 [H(2)O(2)](0)/[Fe(2+)](0), 25 g/L TS, at 25 degrees C and 60 min duration. Further, these optimal conditions were tested for the production of a value added product, Bacillus thuringiensis (Bt) which is being used as a biopesticide in the agriculture and forestry sector. It was observed that Bt growth using Fenton oxidized sludge as a substrate was improved with a maximum total cell count of 1.63 x 10(9)CFU ml(-1) and 96% sporulation after 48 h of fermentation. The results were also tested against ultrasonication treatment and the total cell count was found to be 4.08 x 10(8)CFU ml(-1) with a sporulation of 90%. Hence, classic Fenton oxidation was demonstrated to be a rather more promising chemical pre-treatment for Bt - based biopesticide production using WWS when compared to ultrasonication as a physical pre-treatment.

  13. Predicting impact of multi-paths on phase change in map-based vehicular ad hoc networks

    Science.gov (United States)

    Rahmes, Mark; Lemieux, George; Sonnenberg, Jerome; Chester, David B.

    2014-05-01

    Dynamic Spectrum Access, which through its ability to adapt the operating frequency of a radio, is widely believed to be a solution to the limited spectrum problem. Mobile Ad Hoc Networks (MANETs) can extend high capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact cognitive radio employs spectrum sensing to facilitate identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We quantify optimal signal detection in map based cognitive radio networks with multiple rapidly varying phase changes and multiple orthogonal signals. Doppler shift occurs due to reflection, scattering, and rapid vehicle movement. Path propagation as well as vehicle movement produces either constructive or destructive interference with the incident wave. Our signal detection algorithms can assist the Doppler spread compensation algorithm by deciding how many phase changes in signals are present in a selected band of interest. Additionally we can populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate Dynamic Spectrum Access. We show how topography can help predict the impact of multi-paths on phase change, as well as about the prediction from dense traffic areas. Utilization of high resolution geospatial data layers in RF propagation analysis is directly applicable.

  14. Design of high-precision and multi-channel radar generator based on AD9959%基才AD9959的高精度多通道雷达信号源设计

    Institute of Scientific and Technical Information of China (English)

    宋征; 许国宏; 李星

    2012-01-01

    In order to ensure precision of power synthesize in phased array radar, a kind of high-precision multi-channel radar generator based on AD9959 is designed. Radar generator use host computer and FPGA to control ad9959 and Produce 32 channel sine wave.linear frequency modulation and encoding and so on, designed a multi--channel signal amplitude and phase measuring and adjustment system using ad8302. The radar generator have been applied in ,project, and the experimental results showed that the radar generator had several advantages such as high frequency stability, high precise of phase amplitude consistency, which fully meet the techinical requirements and performance index of the radar generator in phased array radar.%现代相控阵雷达为了保证空间功率合成精度需要高精度的雷达信号。设计实现了一种以AD9959为核心的高精度多通道雷达信号源。信号源利用多片AD9959产生32路正弦波、线性调频以及相位编码等多种信号形式.并设计采用AD8302对多路信号的幅度和相位进行检测与调整。该信号源已应用实际工程中,现场实验结果表明,该信号源系统产生的高频信号频率稳定度高、相位幅度一致性好,完全满足对信号源的性能指标的要求。

  15. Value Adding Management

    DEFF Research Database (Denmark)

    Jensen, Per Anker; Katchamart, Akarapong

    2011-01-01

    Purpose: To investigate how Facilities Management (FM) can add value and develop a management concept that can assist facilities managers in implementing value adding strategies and practices. Theory: The study is based on the management model for FM included in the European FM standards, recent...... theories on added value of FM and real estate and the related concept of Value Management from building projects. The study is related to the EuroFM research group on The Added Value of FM. Design/methodology/approach: The study outlines a preliminary theoretical based management concept, which...... is investigated, tested and discussed based on a case study of an international corporation. Findings: The study shows that the management model for FM creates a relevant starting point but also that stakeholder and relationship management is an essential aspect of Value Adding Management. The case study confirms...

  16. 基于NS2的Ad Hoc网络DRMR协议计算机仿真%Computer Simulation of DRMA Protocol in Ad Hoc Network Based on NS2

    Institute of Scientific and Technical Information of China (English)

    梁凤山

    2011-01-01

    针对现存多种Ad Hoc组播路由协议的有效性差、控制开销大等问题,设计并实现了一种基于动态广播环的组播路由(DRMR:Dynamic Ring based Multicast Routing)协议,确定了DRMR协议的实现框架,定义了各功能模块.在该协议中,组播路由建立和维护每个组成员广播环所构成的连通环图,当组成员广播环离开连通环图时,采用逐步扩大广播环的半径恢复其连通性.仿真结果表明,DRMR协议具有较高的数据分组递交率和较低的路由维护开销,其总体控制开销比基于需求的多播路由协议节省,能满足Ad Hoc网络对组播应用的要求,对研究Ad Hoc网络人员具有实际参考价值.%Airuing at problems of low efficiency and high overhead of control packets in the existing multicast routing protocols for ad hoc networks , a novel multicast routing protocol for Ad Hoc networks called DRMR ( Dynamic Ring based Multicast Routing ) protocol was designed and realized. The implemented framework of DRMR was established and the function modules were defined. In DRMR, the multicast routing is carried out through establishing and maintaining the connected ring graph which is constructed from dynamic broadcast rings held by each member group. When the group member broadcast departs from the connected ring graph, the connectivity can be recovered by gradually extend the radius of broadcasting. Simulation results show that DRMR has a high data packet delivery ratio and low routing maintenance cost, and its total control overhead is reduced more compared with the multicast routing protocols based on requirements. It can meet the requirements of the multicast applications in ad hoc networks. The results of this study have practical reference significance for Ad Hoc network reserchers.

  17. Researching on Multipath Routing Protocol Based on AODV for Ad Hoc Networking%基于AODV的Ad Hoc网络多路径路由协议

    Institute of Scientific and Technical Information of China (English)

    周杰

    2012-01-01

    Multi-path AODV routing protocol(MP-AODV) uses the repetitive RREQ packets received by the nodes in AODV routing protocol to build the multi-path routes. Simulation based on NS2 software indicates that both datagram successful transmission rate and delay time is improved, being compared with the AODV routing protocol.%多路径AODV路由协议(MP-AODV)有效利用AODV协议中中间节点收到的多个RREQ报文来建立多路径路由。基于NS2模拟软件的路由协议仿真结果显示,MP-AODV路由协议的数据报传输成功率和平均延迟时间比AODV路由协议均有了提高。

  18. 基于AD8302的高精度幅相检测系统的设计%Design of Magnitude and Phase Measuring System with High Precision Based on AD8302

    Institute of Scientific and Technical Information of China (English)

    刘静; 马彦恒

    2011-01-01

    In order to raise the accuracy of the magnitude and phase measuring, predigest the circuit, enlarge the range of the frequence, the paper introduces the chip of AD8302, which is used to measure the RF/IF gain/ loss and phase.Then compose the magnitude and phase measuring system with high precision based on AD8302 and MCU, to realize the measurement of the magnitude and phase of the two simulated input signals, and compose the judgement circuit of phase polarity with Schmitt trigger and D trigger, enlarge the range of the frequence test to 0- 360°.The system can measure the magnitude and phase accurately of the input signal.The results shows that magnitude and phase measuring system based on AD8302 has the advantages of precision and strong anti-jamming.%为了提高幅相测量精度、简化电路,扩展频率范围,介绍了一种用于RF/IF幅度和相位测量的AD8302芯片;并利用此芯片和单片机组成高精度幅相检测系统,主要是以实现两路模拟输入信号的相位差和幅度比测量为目的;并利用分频器、施密特触发器和D触发器组成相位极性判断电路,扩展相位测量范围为0~360°;该系统能精确测量两输入信号的幅度比和相位差,测试结果表明基于AD8302的幅相检测系统具有精度高、抗干扰能力强等优点.

  19. Monitoring and classifying animal behavior using ZigBee-based mobile ad hoc wireless sensor networks and artificial neural networks

    DEFF Research Database (Denmark)

    S. Nadimi, Esmaeil; Nyholm Jørgensen, Rasmus; Blanes-Vidal, Victoria

    2012-01-01

    Animal welfare is an issue of great importance in modern food production systems. Because animal behavior provides reliable information about animal health and welfare, recent research has aimed at designing monitoring systems capable of measuring behavioral parameters and transforming them...... into their corresponding behavioral modes. However, network unreliability and high-energy consumption have limited the applicability of those systems. In this study, a 2.4-GHz ZigBee-based mobile ad hoc wireless sensor network (MANET) that is able to overcome those problems is presented. The designed MANET showed high...... communication reliability, low energy consumption and low packet loss rate (14.8%) due to the deployment of modern communication protocols (e.g. multi-hop communication and handshaking protocol). The measured behavioral parameters were transformed into the corresponding behavioral modes using a multilayer...

  20. Cross-Network Information Dissemination in Vehicular Ad hoc Networks (VANETs: Experimental Results from a Smartphone-Based Testbed

    Directory of Open Access Journals (Sweden)

    Gianluigi Ferrari

    2013-08-01

    Full Text Available In this work, we present an innovative approach for effective cross-network information dissemination, with applications to vehicular ad hoc networks (VANETs. The proposed approach, denoted as "Cross-Network Effective Traffic Alert Dissemination" (X-NETAD, leverages on the spontaneous formation of local WiFi (IEEE 802.11b VANETs, with direct connections between neighboring vehicles, in order to disseminate, very quickly and inexpensively, traffic alerts received from the cellular network. The proposed communication architecture has been implemented on Android smartphones. The obtained experimental results show that an effective cross-network information dissemination service can entirely rely on smartphone-based communications. This paves the way to future Internet architectures, where vehicles will play a key role as information destinations and sources.

  1. Distributed Position Localization and Tracking (DPLT) of Malicious Nodes in Cluster Based Mobile Ad hoc Networks (MANET)

    CERN Document Server

    Niraj, Shakhakarmi

    2012-01-01

    In this paper, a robust distributed malicious node detection and precise localization and tracking method is proposed for Cluster based Mobile Ad hoc Network (MANET). Certificate Authority (CA) node is selected as the most stable node among trusted nodes, surrounded by Registration Authority nodes (RAs) in each cluster to generate the Dynamic Demilitarized Zone (DDMZ) to defend CA from probable attackers and mitigate the authentication overhead. The RAs also co-operate with member nodes to detect a target node and determine whether it is malicious or not, by providing the public key certificate and trust value. In addition, Internet Protocol (IP) based Triangulation and multi-lateration method are deployed based on using the average time difference of Time of Arrival (ToA) and Time of Departure (ToD) of the management packets. Triangulation uses three reference nodes which are elected within each cluster based on Best Criterion Function (BCF) to localize each member node inside the cluster in 2D. Multi-latera...

  2. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers

    Science.gov (United States)

    Alvarez, María Dolores; Cuesta, Francisco Javier; Herranz, Beatriz; Canet, Wenceslao

    2017-01-01

    An attempt was made to analyze the elastic modulus (G′) of chickpea flour (CF)-based muffin batters made with CF alone and with added biopolymers (whey protein (WP), xanthan gum (XG), inulin (INL), and their blends) in order to evaluate their suitability to be a wheat flour (WF) substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 °C to 90 °C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n), frequency factor (k0), and activation energy (Ea)) using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G′ value. The change of the derivative of G′ with respect to time (dG′/dt) versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol−1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins. PMID:28231082

  3. Research based on the wormhole attack and defense of the Ad Hoc%基于Ad Hoc的虫洞攻击与防御研究综述

    Institute of Scientific and Technical Information of China (English)

    黄成兵

    2012-01-01

    Based on the analysis of wireless Ad Hoc network routing protocols Research,pointed out that the wireless Ad Hoc network routing protocols vulnerability and initiated several major attacks in the form of protocol vulnerabilities.The focus of analysis of the basic principles of the wormhole attack,its defense and deficiencies,and to lay the foundation for further study in the future secure routing protocol.%本文在分析无线Ad Hoc网络路由协议研究现状的基础上,指出无线Ad Hoc网络路由协议存在的脆弱性及针对协议漏洞所发起的几种主要攻击形式。重点分析虫洞攻击的基本原理及其当前的防御方法和不足,为今后更进一步研究安全路由协议打下基础。

  4. Applying object-based image analysis and knowledge-based classification to ADS-40 digital aerial photographs to facilitate complex forest land cover classification

    Science.gov (United States)

    Hsieh, Yi-Ta; Chen, Chaur-Tzuhn; Chen, Jan-Chang

    2017-01-01

    In general, considerable human and material resources are required for performing a forest inventory survey. Using remote sensing technologies to save forest inventory costs has thus become an important topic in forest inventory-related studies. Leica ADS-40 digital aerial photographs feature advantages such as high spatial resolution, high radiometric resolution, and a wealth of spectral information. As a result, they have been widely used to perform forest inventories. We classified ADS-40 digital aerial photographs according to the complex forest land cover types listed in the Fourth Forest Resource Survey in an effort to establish a classification method for categorizing ADS-40 digital aerial photographs. Subsequently, we classified the images using the knowledge-based classification method in combination with object-based analysis techniques, decision tree classification techniques, classification parameters such as object texture, shape, and spectral characteristics, a class-based classification method, and geographic information system mapping information. Finally, the results were compared with manually interpreted aerial photographs. Images were classified using a hierarchical classification method comprised of four classification levels (levels 1 to 4). The classification overall accuracy (OA) of levels 1 to 4 is within a range of 64.29% to 98.50%. The final result comparisons showed that the proposed classification method achieved an OA of 78.20% and a kappa coefficient of 0.7597. On the basis of the image classification results, classification errors occurred mostly in images of sunlit crowns because the image values for individual trees varied. Such a variance was caused by the crown structure and the incident angle of the sun. These errors lowered image classification accuracy and warrant further studies. This study corroborates the high feasibility for mapping complex forest land cover types using ADS-40 digital aerial photographs.

  5. Dynamic Subchannel Assignment-Based Cross-Layer MAC and Network Protocol for Multihop Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Khanh Nguyen Quang

    2013-01-01

    Full Text Available The paper presents a dynamic subchannel assignment algorithm based on orthogonal frequency division multiple access technology operating in the time division duplexing and a new cross-layer design based on a proposed routing protocol jointed with the MAC protocol. The proposed dynamic sub-channel assignment algorithm provides a new interference avoidance mechanism which solves several drawbacks of existing radio resource allocation techniques in wireless networks using OFDMA/TDD, such as the hidden node and exposed node problems, mobility, and cochannels interference in frequency (CCI. Besides, in wireless networks, when a route is established, the radio resource allocation problems may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may cause the routing protocol at network layer to respond by finding new routes and routing table updates. The proposed routing protocol is jointed with the MAC protocol based on dynamic sub-channel assignment to ensure that the quality of service in multihop ad hoc networks is significantly improved.

  6. An Improved Location aided Cluster Based Routing Protocol with Intrusion Detection System in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    S. Mangai

    2011-01-01

    Full Text Available Problem statement: Routing and security are the main challenges for ad hoc networks due to dynamic topology as well as resource constraints. A designed protocol must provide scalable routing with better security. Lack of any central coordination and shared wireless medium makes them more vulnerable to attacks than wired networks. And also resource constraints such as limited energy and size also play an important role in the protocols designed for security. Approach: In this study, Improved Location aided Cluster based Routing Protocol (ILCRP for GPS enabled MANETs was analysed in MANETs with malicious nodes and an Intrusion Detection System was used to increase the packet delivery ratio. ILCRP makes use of location aided routing in the presence of cluster based routing Protocol. Results: Use of location information with security against attacks results in high packet delivery ratio for the cluster based routing protocol. Simulations are performed using NS2 by varying the number of nodes. Conclusion: The results illustrate ILCRP provides higher delivery ratio with IDS.

  7. Facebook Ads Recruit Parents of Children with Cancer for an Online Survey of Web-Based Research Preferences

    Science.gov (United States)

    Akard, Terrah Foster; Wray, Sarah; Gilmer, Mary

    2014-01-01

    Background Studies involving samples of children with life-threatening illnesses and their families face significant challenges, including inadequate sample sizes and limited diversity. Social media recruitment and web-based research methods may help address such challenges yet have not been explored in pediatric cancer populations. Objective This study examined the feasibility of using Facebook ads to recruit parent caregivers of children and teens with cancer. We also explored the feasibility of web-based video recording in pediatric palliative care populations by surveying parents of children with cancer regarding (a) their preferences for research methods and (b) technological capabilities of their computers and phones. Methods Facebook's paid advertising program was used to recruit parent caregivers of children currently living with cancer to complete an electronic survey about research preferences and technological capabilities. Results The advertising campaign generated 3,897,981 impressions which resulted in 1050 clicks at a total cost of $1129.88. Of 284 screened individuals, 106 were eligible. Forty-five caregivers of children with cancer completed the entire electronic survey. Parents preferred and had technological capabilities for web-based and electronic research methods. Participant survey responses are reported. Conclusion Facebook was a useful, cost-effective method to recruit a diverse sample of parent caregivers of children with cancer. Web-based video recording and data collection may be feasible and desirable in samples of children with cancer and their families. Implications for Practice Web-based methods (e.g., Facebook, Skype) may enhance communication and access between nurses and pediatric oncology patients and their families. PMID:24945264

  8. Simulation of the automatic depressurization system (Ads) for a boiling water reactor (BWR) based on RELAP; Simulacion del sistema de despresurizacion automatica (ADS) para un reactor de agua en ebullicion (BWR) basado en RELAP

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, C.; Chavez M, C., E-mail: ces.raga@gmail.com [UNAM, Facultad de Ingenieria, Circuito Interior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2012-10-15

    The automatic depressurization system (Ads) of the boiling water reactor (BWR) like part of the emergency cooling systems is designed to liberate the vapor pressure of the reactor vessel, as well as the main vapor lines. At the present time in the Engineering Faculty, UNAM personnel works in the simulation of the Laguna Verde reactor based on the nuclear code RELAP/SCADAP and in the incorporation to the same of the emergency cooling systems. The simulation of the emergency cooling systems began with the inclusion of two hydrodynamic volumes, one source and another drain, and the incorporation of the initiation logic for each emergency system. In this work is defined and designed a simplified model of Ads of the reactor, considering a detail level based on the main elements that compose it. As tool to implement the proposed model, the RELAP code was used. The simulated main functions of Ads are centered in the quick depressurization of the reactor by means of the vapor discharge through the relief/safety valves to the suppression pool, and, in the event of break of the main vapor line, the reduction of the vessel pressure operates for that the cooling systems of the core to low pressure (Lpcs and Lpci) they can begin their operation. (Author)

  9. Design of Ultrasonic Phased Array Inspection System Based on AD9273%基于AD9273的超声相控阵检测系统设计

    Institute of Scientific and Technical Information of China (English)

    刘建; 徐大专

    2012-01-01

    This paper presents a highly integrated ultrasonic phased array inspection system based on AD9273. The system is designed based on traditional ultrasound phased array inspection system. In the system, some new and highly integrated chips, such as AD9273 and HV748, are used to complete 32-channel high-voltage transmitter and receiver acquisition circuit, FPGA subsystem and ARM platform are used to constitute the core of digital signal processing part, and digital quadrature envelope detector is used to complete the receiver beamforming. The system meets the real-time, high-speed requirements of detection systems. Significant improvement appears in the system's level of miniaturization and digitization. This solution provides the basis for Portable ultrasonic phased array inspection system.%提出了一种基于AD9273的高集成度超声相控阵检测系统设计方案。在传统超声相控阵检测系统的基础上,利用新型高集成度芯片AD9273和HV748完成32通道高压发射电路和接收采集电路设计;采用FPGA子系统结合ARM平台的方式构成系统数字信号处理的核心;采用数字正交包络检波技术完成接收波束成形。系统满足探伤的实时、高速的要求。系统在小型化和数字化方面有显著提高,可为便携式超声相控阵检测系统设计奠定基础。

  10. 基于AD5933的32通道岩土水分测量仪的研制%Design of 32-Channel Soil Moisture Meter Based on AD5933

    Institute of Scientific and Technical Information of China (English)

    刘亮; 伍群芳; 赖建英; 刁心宏; 彭皓

    2014-01-01

    基于将岩土水分转化成电信号测量的原理,研制出了一种以STM32为控制核心,以阻抗转换芯片AD5933为测量核心的32通道岩土介质水分测试仪系统。系统具有自动测量,自动校准,支持USB通讯等功能。测量实验表明,系统具有稳定可靠,测量精度高,体积小、低成本、操作简单等优点,具有很好的工程应用价值。%Based on the measurement principle of converting soil moisture measurement into electrical signal, this paper designs a 32-channel soil moisture meter which adopts STM32 as the control core and impedance con-version chip AD5933 as the measuring core. The system has the functions of automatic control,automatic cor-rection and supporting USB communication and so on. Results show that the measuring instrument has the ad-vantages of highly integrated circuits,easy operation,and high accuracy,stable and reliable performance, which may have wide engineering applications.

  11. Neural methods based on modified reputation rules for detection and identification of intrusion attacks in wireless ad hoc sensor networks

    Science.gov (United States)

    Hortos, William S.

    2010-04-01

    Determining methods to secure the process of data fusion against attacks by compromised nodes in wireless sensor networks (WSNs) and to quantify the uncertainty that may exist in the aggregation results is a critical issue in mitigating the effects of intrusion attacks. Published research has introduced the concept of the trustworthiness (reputation) of a single sensor node. Reputation is evaluated using an information-theoretic concept, the Kullback- Leibler (KL) distance. Reputation is added to the set of security features. In data aggregation, an opinion, a metric of the degree of belief, is generated to represent the uncertainty in the aggregation result. As aggregate information is disseminated along routes to the sink node(s), its corresponding opinion is propagated and regulated by Josang's belief model. By applying subjective logic on the opinion to manage trust propagation, the uncertainty inherent in aggregation results can be quantified for use in decision making. The concepts of reputation and opinion are modified to allow their application to a class of dynamic WSNs. Using reputation as a factor in determining interim aggregate information is equivalent to implementation of a reputation-based security filter at each processing stage of data fusion, thereby improving the intrusion detection and identification results based on unsupervised techniques. In particular, the reputation-based version of the probabilistic neural network (PNN) learns the signature of normal network traffic with the random probability weights normally used in the PNN replaced by the trust-based quantified reputations of sensor data or subsequent aggregation results generated by the sequential implementation of a version of Josang's belief model. A two-stage, intrusion detection and identification algorithm is implemented to overcome the problems of large sensor data loads and resource restrictions in WSNs. Performance of the twostage algorithm is assessed in simulations of WSN

  12. Adding problem-based learning tutorials to a traditional lecture-based curriculum: a pilot study in a dental school.

    Science.gov (United States)

    Katsuragi, Hiroaki

    2005-09-01

    This article reports on the implementation of a problem-based learning (PBL) tutorial in our advanced program for second year students within an existing curriculum. The program was opened on the last 5 days of the summer vacation and students could volunteer to be part of the group. Students separated themselves into small groups by random sampling. The PBL tutorials were done during the first 3 days for medical problems according to our original scenarios (based on medical cases), and during the last 2 days, students made presentations of their learning outcomes, using information technology (IT) by themselves. Throughout this program, students were expected to engage in self-learning, except for a 1(1/2)-h group session with a tutor. Assessment was done by attendance at a group session and by portfolio analysis. Following the portfolio analysis, students identified the number of learning issues (group A, 26 +/- 7 issues; group B, 20 +/- 3 issues; group C, 21 +/- 7 issues). Research, by questionnaire, revealed that 84% of the students were strongly interested in each scenario and 95% of the students felt familiar with each scenario. The levels of satisfaction with the tutor were different in the three groups. All of the students were comfortable in the discussion room and IT center. These results suggested that PBL tutorials are supported by the scenario, the tutor, and the location of the group session, as well as by self-learning. Moreover, one of the most important factors for a PBL tutorial that the student is ready for the free discussions and has enough time for individual self-learning.

  13. Secure Communication and Information Exchange using Authenticated Ciphertext Policy Attribute-Based Encryption in Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    Samsul Huda

    2016-08-01

    Full Text Available MANETs are considered as suitable for commercial applications such as law enforcement, conference meeting, and sharing information in a student classroom and critical services such as military operations, disaster relief, and rescue operations. Meanwhile, in military operation especially in the battlefield in freely medium which naturally needs high mobility and flexibility. Thus, applying MANETs make these networks vulnerable to various types of attacks such aspacket eavesdropping, data disseminating, message replay, message modification, and especially privacy issue. In this paper, we propose a secure communication and information exchange in MANET with considering secure adhoc routing and secure information exchange. Regarding privacy issue or anonymity, we use a reliable asymmetric encryption which protecting user privacy by utilizing insensitive user attributes as user identity, CP-ABE (Ciphertext-Policy Attribute-Based Encryption cryptographic scheme. We also design protocols to implement the proposed scheme for various battlefied scenarios in real evironment using embedded devices. Our experimental results showed that the additional of HMAC (Keyed-Hash Message Authentication Code and AES (Advanced Encryption standard schemes using processor 1.2GHz only take processing time about 4.452 ms,  we can confirm that our approach by using CP-ABE with added HMAC and AES schemes make low overhead.

  14. Load balancing strategy of heterogeneous wireless networks based on multi-hop routing algorithm of ad hoc network

    Institute of Scientific and Technical Information of China (English)

    Pei Xuebing; Wang Qingping; Zhu Guangxi; Liu Gan

    2009-01-01

    Because of different system capacities of base station (BS) or access point (AP) and ununiformity of traffic distribution in different cells, quantities of new call users may be blocked in overloaded cell in communication hot spots. Whereas in some neighboring under-loaded cells, bandwidth may be superfluous because there are only few users to request services. In order to raise resource utilization of the whole heterogeneous networks, several novel load balancing strategies are proposed, which combine the call admission control policy and multi-hop routing protocol of ad-hoc network for load balancing. These load balancing strategies firstly make a decision whether to admit a new call or not by considering some parameters like load index and route cost, etc.., and then transfer the denied users into neighboring under-loaded cell with surplus channel according to optimum multi-hop routing algorithm. Simulation results show that the proposed load balancing strategies can distribute traffics to the whole heterogeneous wireless networks, improve the load balance index efficiently, and avoid the call block phenomenon almost absolutely.

  15. Intrusion prevention and Message Authentication Protocol (IMAP using Region Based Certificate Revocation List Method in Vehicular Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    G. Anitha

    2014-05-01

    Full Text Available Vehicular Ad-hoc network uses some advanced Public Key Infrastructure and digital signature method for security. But, intrusion detection and avoidance is an inevitable challenge in networks. Authentication is performed in any PKI (Public Key Infrastructure system by checking if the certificate of the sender is included in the CRL (Certificate Revocation List and verifying the authenticity and checking the sign of the sender. This study focuses on efficient certificate revocation list management by region based certificate revocation list distribution protocol. Instead of storing all invalid vehicle identity in a single CRL, each region maintains a separate CRL which contains the invalid vehicle's identity in the region. This CRL checking process has been done using by Hash function technique, i.e., Bloom Filter which avoids false negative. It replaces the time-consuming CRL Checking process. This protocol can reduce message loss ratio by using fast revocation checking and the CRL updating method as well as it needs very less memory space compared to other methods.

  16. A contention-based efficient-information perception algorithm (CEiPA) for vehicular ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    Chen Lijia; Jiang Hao; Yan Puliu

    2009-01-01

    The problem of information dissemination is researched for vehicular ad-hoc networks (VANET) in this paper, and a contention-based efficient-information perception algorithm (CEiPA) is proposed. The idea of CEiPA is that beacons are delivered over VANET with limited lifetime and efficient information. CEiPA consists of two phases. The first one is initialization phase, during which the count timers Tcycle and Tlocal are set to start beacon delivery while Tcycle is also used to monitor and restart beaconing. The second one is beacon delivery phase. An elaborate distance function is employed to set contention delay for beacons of each vehicle. In this way beacons will be sent in order, which decreases the collision of beacons. Simulation results show that CEiPA enables each beacon to carry more efficient information and spread them over more vehicles with lower network overhead than the periodic beacon scheme. CEiPA is also flexible and scalable because the efficient information threshold it employs is a balance among the freshness of information, network overhead and perception area of a vehicle.

  17. Improving Performance and Versatility of Systems Based on Single-Frequency DFT Detectors Such as AD5933

    Directory of Open Access Journals (Sweden)

    Leonid Matsiev

    2014-12-01

    Full Text Available Turning grand concepts such as the Internet of Things (IoT and Smart Cities into reality requires the development and deployment of a wide variety of computing devices incorporated into the Internet infrastructure. Unsupervised sensing is the cornerstone capability that these devices must have to perform useful functions, while also having low cost of acquisition and ownership, little energy consumption and a small footprint. Impedimetric sensing systems based on the so-called single-frequency DFT detectors possess many of these desirable attributes and are often introduced in remote monitoring and wearable devices. This study presents new methods of improving performance of such detectors. It demonstrates that the main source of systematic errors is the discontinuous test phasor causing the crosstalk between the in-phase and quadrature outputs and the leakage of the input signal. The study derives expressions for these errors as a function of the number of samples and operating frequency, and provides methods for correction. The proposed methods are applied to the operation of a practical device—a network analyzer integrated circuit AD5933—and discussed in detail. These methods achieve complete elimination of leakage errors and expansion of the low limit of the operation frequency range by nearly two decades without additional hardware.

  18. Tree-ring based reconstructions of interannual to decadal scale precipitation variability for northeastern Utah since 1226 A.D.

    Science.gov (United States)

    Gray, S.T.; Jackson, S.T.; Betancourt, J.L.

    2004-01-01

    Samples from 107 pin??on pines (Pinus edulis) at four sites were used to develop a proxy record of annual (June to June) precipitation spanning the 1226 to 2001 AD interval for the Uinta Basin Watershed of northeastern Utah. The reconstruction reveals significant precipitation variability at interannual to decadal scales. Single-year dry events before the instrumental period tended to be more severe than those after 1900. In general, decadal scale dry events were longer and more severe prior to 1900. In particular, dry events in the late 13th, 16th, and 18th Centuries surpass the magnitude and duration of droughts seen in the Uinta Basin after 1900. The last four decades of the 20th Century also represent one of the wettest periods in the reconstruction. The proxy record indicates that the instrumental record (approximately 1900 to the Present) underestimates the potential frequency and severity of severe, sustained droughts in this area, while over representing the prominence of wet episodes. In the longer record, the empirical probability of any decadal scale drought exceeding the duration of the 1954 through 1964 drought is 94 percent, while the probability for any wet event exceeding the duration of the 1965 through 1999 wet spell is only 1 percent. Hence, estimates of future water availability in the Uinta Basin and forecasts for exports to the Colorado River, based on the 1961 to 1990 and 1971 to 2000 "normal" periods, may be overly optimistic.

  19. Ad Hoc网络中基于身份的密钥管理及认证%An Identity-based Key Management and Authentication in Wireless Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    肖希; 金亮

    2012-01-01

    In this paper, a distributed key management and authentication approach based on identity in wireless Ad Hoc network is introduced. Each node uses the identity as its public key. The master private is shared by the private key of every node. Threshold and identity-based key management and authentication are used. The identity-based mechanism is applied here not only to provide end-to-end authenticity and confidentiality, but also to save network bandwidth and computational power of wireless nodes. It is very efficient and robust to transfer packets.%提出了在AdHoe网络中一种分布式基于身份的密钥管理及认证方法。每个节点使用其身份作为公钥,主密钥由各节点的私钥分享,从而形成基于身份的门限分布式密钥管理。该方法不仅提供了点对点的认证,而且节省了网络带宽和节点的能量消耗,具有很高的效率和鲁棒性。

  20. Benefits of adding small financial incentives or optional group meetings to a web-based statewide obesity initiative.

    Science.gov (United States)

    Leahey, Tricia M; Subak, Leslee L; Fava, Joseph; Schembri, Michael; Thomas, Graham; Xu, Xiaomeng; Krupel, Katie; Kent, Kimberly; Boguszewski, Katherine; Kumar, Rajiv; Weinberg, Brad; Wing, Rena

    2015-01-01

    To examine whether adding either small, variable financial incentives or optional group sessions improves weight losses in a community-based, Internet behavioral program. Participants (N = 268) from Shape Up Rhode Island 2012, a 3-month Web-based community wellness initiative, were randomized to: Shape Up+Internet behavioral program (SI), Shape Up+Internet program+incentives (SII), or Shape Up+Internet program+group sessions (SIG). At the end of the 3-month program, SII achieved significantly greater weight losses than SI (SII: 6.4% [5.1-7.7]; SI: 4.2% [3.0-5.6]; P = 0.03); weight losses in SIG were not significantly different from the other two conditions (SIG: 5.8% [4.5-7.1], P's ≥ 0.10). However, at the 12-month no-treatment follow-up visit, both SII and SIG had greater weight losses than SI (SII: 3.1% [1.8-4.4]; SIG: 4.5% [3.2-5.8]; SI: 1.2% [-0.1-2.6]; P's ≤ 0.05). SII was the most cost-effective approach at both 3 (SII: $34/kg; SI: $34/kg; SIG: $87/kg) and 12 months (SII: $64/kg; SI: $140/kg; SIG: $113/kg). Modest financial incentives enhance weight losses during a community campaign, and both incentives and optional group meetings improved overall weight loss outcomes during the follow-up period. However, the use of the financial incentives is the most cost-effective approach. © 2014 The Obesity Society.

  1. 一种基于分层结构的Ad Hoc网络分簇路由协议研究%Research based on the hierarchical structure of the Ad Hoc network clustering routing protocol

    Institute of Scientific and Technical Information of China (English)

    冯永亮

    2015-01-01

    The traditional Ad Hoc network clustering routing protocol has low packet delivery ratio problem, this paper proposes a clustering routing protocol based on hierarchical structure. The advanced network layer using AODV routing protocol based backup, and the lower network layer adopts a smaller delay DSDV protocol. The simulation results show that the improved routing protocol improves the packet delivery rate, Shortening the end to end delay.%传统Ad Hoc网络分簇路由协议存在分组投递率低的问题,论文提出一种基于分层结构的分簇路由协议.高级网络层采用基于备份路由的AODV协议,而低级网络层则采用时延较小的DSDV协议.仿真结果显示,改进后的路由协议提高了分组投递率,缩短了端到端时延.

  2. Effects of different yeast cell wall supplements added to maize- or wheat-based diets for broiler chickens.

    Science.gov (United States)

    Morales-López, R; Auclair, E; Van Immerseel, F; Ducatelle, R; García, F; Brufau, J

    2010-06-01

    1. Three experiments were carried out to study the effects of two experimental yeast cell wall (YCW) supplements, one from the yeast extract industry and the other from the brewery industry, added to maize or wheat based-diets, on performance and intestinal parameters of broiler chickens (Ross 308). 2. In the first and second experiments, a completely randomised block design with 4 experimental treatments was used: T-1) Negative control, no additives T-2) Positive control, avilamycin group (10 mg/kg feed), T-3) Yeast extract-YCW (500 mg/kg), and T-4) Brewery-YCW (500 mg/kg feed). There were 6 replicates of 20 (experiment 1) and 22 (experiment 2) chicks per treatment. 3. In experiment 1 (wheat based diets), yeast extract-YCW increased BW and daily feed intake (42 d). The effects were comparable to those of avilamycin. In experiment 2 (maize based diet), avilamycin, yeast extract-YCW and brewery-YCW treatments improved the feed conversion ratio with respect to the negative control group (0 to 14 d). 4. At 24 d, in both experiments, the ileal nutrient digestibility and ileal bacterial counts were not affected by any experimental treatment. In maize diets, lower intestinal viscosity was obtained with avilamycin, yeast extract-YCW and brewery-YCW than with the negative control. In wheat diets, yeast extract-YCW and brewery-YCW reduced intestinal viscosity. 5. A third experiment was conducted to study the effect of yeast extract-YCW on animal performance, intestinal mucosa morphology and intestinal viscosity. A 2 x 2 factorial arrangement of treatments was used; one factor was the dietary yeast extract-YCW supplementation (0 or 500 mg/kg feed) and the other the cereal in the diet (maize or wheat). 6. At 43 d, the heaviest BW was in chickens fed on yeast extract-YCW compared to those given the negative control. At 22 d, yeast extract-YCW increased villus height, mucus thickness and number of goblet cells with respect to negative control. 7. Results of these experiments

  3. Relationships between Microstructural Parameters and Time-Dependent Mechanical Properties of a New Nickel-Based Superalloy AD730™

    Directory of Open Access Journals (Sweden)

    Louis Thébaud

    2015-11-01

    Full Text Available High temperature creep and dwell-fatigue properties of the new nickel-based superalloy AD730™ have been investigated. Three microstructures have been studied in creep (850 °C and 700 °C and dwell-fatigue (700 °C stress control with trapezoidal signals, and dwell times ranging from 1 s to 3600 s: a coarse grains microstructure, a fine grains one, and single crystalline samples. The aim of this study is to assess the influence of the grain size on creep and creep-fatigue properties. It is demonstrated that fine and coarse grains microstructures perform similarly in creep at 700 °C, showing that the creep properties at this temperature are controlled by the intragranular precipitation. Moreover, both the coarse grains and the fine grains microstructures show changes in creep deformation mechanisms depending on the applied stress in creep at 700 °C. At higher creep temperatures, the coarse grains microstructure performs better and almost no effect is observed by suppressing grain boundaries. During dwell-fatigue tests at 700 °C, a clear effect of the mechanical cycling has been evidenced on the time to failure on both the coarse and the fine grains microstructures. At high applied stresses, a beneficial effect of the cyclic unloading to the lifetime has been observed whereas at lower applied stresses, mechanical cycling is detrimental compared to the pure creep lifetime due to the development of a fatigue damage. Complex creep-fatigue interactions are hence clearly evidenced and they depend on the pure creep behavior reference.

  4. Global geometric properties of AdS space and the AdS/CFT correspondence

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Poisson kernels and relations between them for a massive scalar field in a unit ball Bn with Hua's metric and conformal flat metric are obtained by describing the Bn as a submanifold of an (n+1)-dimensional embedding space. Global geometric properties of the AdS space are discussed. We show that the(n+1)-dimensional AdS space AdSn+1 is isomorphic to RP1×Bn and boundary of the AdS is isomorphic to RP1×Sn-1. Bulk-boundary propagator and the AdS/CFT like correspondence are demonstrated based on these global geometric properties of the RP1×Bn.

  5. Online Ad Assignment with an Ad Exchange

    OpenAIRE

    Dvořák, Wolfgang; Henzinger, Monika

    2016-01-01

    Ad exchanges are becoming an increasingly popular way to sell advertisement slots on the internet. An ad exchange is basically a spot market for ad impressions. A publisher who has already signed contracts reserving advertisement impressions on his pages can choose between assigning a new ad impression for a new page view to a contracted advertiser or to sell it at an ad exchange. This leads to an online revenue maximization problem for the publisher. Given a new impression to sell decide whe...

  6. Complexity Growth for AdS Black Holes

    CERN Document Server

    Cai, Rong-Gen; Wang, Shao-Jiang; Yang, Run-Qiu; Peng, Rong-Hui

    2016-01-01

    We further investigate the Complexity-Action (CA) duality conjecture for stationary anti de-Sitter (AdS) black holes and derive some exact results for the growth rate of action within Wheeler-DeWitt (WDW) patch at late time approximation, which is dual to the growth rate of quantum complexity of holographic state. Based on the results from the general $D$-dimensional Reissner-Nordstr\\"{o}m (RN)-AdS black hole, rotating/charged Ba\\~{n}ados-Teitelboim-Zanelli (BTZ) black hole, Kerr-AdS black hole and charged Gauss-Bonnet-AdS black hole, we present a new complexity bound but leave unchanged the conjecture that the stationary AdS black hole in Einstein gravity is the fastest computer in nature.

  7. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Nonlinear Preference

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-Yue; YANG Qiu-Ying; CHEN Tian-Lun

    2007-01-01

    We introduce a modified small-world network adding new links with nonlinearly preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. We study several important structural properties of our network such as the distribution of link-degree, the maximum link-degree, and the length of the shortest path. We further argue several dynamical characteristics of the model such as the important critical value fc, the f0 avalanche, and the mutating condition, and find that those characteristics show particular behaviors.

  8. 基于TMS320VC5509与AD7322的数据采集系统的设计%Design of a data acquisition system based on TMS320VC5509 and AD7322

    Institute of Scientific and Technical Information of China (English)

    高峰

    2012-01-01

    In order to enhance the signal sampling rate and conversion accuracy and to reduce system power consumption,a kind of dada acquisition system is designed based on the fixed-point DSP TMS320VC5509 and 2-channel,software-selectable,true bipolar input,1MSPS,12-Bit plus sign,successive approximation type ADC,AD7322,and the principle of hardware circuit and the method of connection and acquisition process are introduced.TCD1206SUP linear CCD with 2160 cells is adopted as image sensor,after CCD completes scanning data,the output of video signals will be filtered by a second-order active low pass circuit,these signals will be collected by the high speed serial ADC,AD7322,which will convert them to digital signals and be sent into DSP.The test result indicates that the system scheme designed is reasonable and design purpose and requirement are reached.%为了提高数据采集系统的采样速度、转换精度、降低系统功耗,设计了一种采用TI公司的C5000系列定点DSP芯片TMS320VC5509和ADI Device公司的2通道的、软件可选的、双极性输入的、最高转换速率是1MSpS、12位的带符号的逐次逼近型串行AD7322的数据采集系统,并阐述了该系统的主要硬件电路的搭建原理、连接方法以及采集过程。该系统的前端数据采集单元采用2160像元的TCD1206SUP线阵CCD作为图像传感器,CCD输出的视频信号经过一个二阶有源低通滤波电路进行滤波后,被高速串行A/D转换器AD7322采集并转换成数字信号,然后将数字信号送进DSP。通过测试表明,该系统设计方案合理,达到了设计目的和要求。

  9. Design and realization of IFM system based AD8302 in X-band%基于AD8302的X波段瞬时频率测量系统设计

    Institute of Scientific and Technical Information of China (English)

    何源

    2011-01-01

    Introduces some technique of instantaneous frequency measurement,give the system of IFM in X-band based the chip of phase detector AD8302 with the low noise amplifier, mixer, MCU and so on. Then test the overall performance, the result showed that, this sysetem can effectively measure the frequency of the signal in X-band,and the accuracy is better than 10 MHz.%介绍了几种瞬时频率测量技术,为了测量某系统接收到的瞬时信号频率,给出了基于相位检测芯片AD8302配合低噪声放大器、混频器、单片机等设计制作的X波段瞬时频率测量系统.依照方案设计了实物,并对系统整体性能进行了测试,测试结果表明,该系统可以有效的测量X波段信号的频率,测频精度优于10 MHz.

  10. Laser heterodyne interference signal processing system based on AD8302%基于 AD8302的激光外差干涉信号解调技术

    Institute of Scientific and Technical Information of China (English)

    刘丹; 郑宾; 郭华玲; 刘辉

    2015-01-01

    In order to overcome defects of the traditional phase measurement hardware , such as circuit complexity , low measurement precision and narrow band width , a novel signal processing system of a laser heterodyne interferometer was designed based on AD 8302 with good performance .The work theory of the system was analyzed in detail .Static and dynamic experimental data were obtained .The results show that measurement error of the system is less than 0.5°and the measurement resolution of heterodyne interference can reach 0.088nm in theory which is more conductive to measure the microvibration signal .%为了改善传统硬件相位测量中存在电路复杂、测量精度低、工作频带宽窄等诸多缺陷,利用AD8302的良好高频测相能力,设计了一种新的激光外差干涉信号处理系统,分析了其工作原理,并取得了静态、动态实验数据。结果表明,系统测量误差小于0.5°,使外差干涉理论测量分辨率提高到0.088nm,更有利于微振动信号的测量。

  11. Adding Soft-Skills to the Hard Target of Adequacy: The Case for Rearticulation Based on a Multifocal Analysis

    Science.gov (United States)

    Knoeppel, Robert C.; Brewer, Curtis A.; Lindle, Jane Clark; First, Patricia F.

    2009-01-01

    The purpose of this study is to expand the definition of adequacy by adding soft skills as a measure of school productivity. The singular focus on academic standards inherent in education policy has prevented scholars from seeing the concept of adequacy through myriad perspectives and has contributed to a resegregation of schools. Education policy…

  12. [Effect of acupuncture on transmembrane signal pathway in AD mice: an analysis based on lipid-raft proteomics].

    Science.gov (United States)

    Nie, Kun; Zhang, Xue-Zhu; Zhao, Lan; Jia, Yu-Jie; Han, Jing-Xian

    2014-08-01

    To reveal the transmembrane signal pathway participating in regulating neuron functions of treating Alzheimer's disease (AD) by acupuncture. SAMP8 mice was used for AD animal model. The effect of acupuncture method for qi benefiting, blood regulating, health supporting, and root strengthening on the amount and varieties of transmembrane signal proteins from hippocampal lipid rafts in SAMP8 mice was detected using HPLC MS/MS proteomics method. Compared with the control group, acupuncture increased 39 transmembrane signal proteins from hippocampal lipid rafts in SAMP8 mice, of them, 14 belonged to ionophorous protein, 8 to G protein, 8 to transmembrane signal receptor, and 9 to kinase protein. Totally 3 main cell signal pathways were involved, including G-protein-coupled receptors signal, enzyme linked receptor signal, and ion-channel mediated signal. Compared with the sham-acupuncture group, acupuncture resulted in significant increase of kinase signal protein amount. From the aspect of functions, they were dominant in regulating synapse functions relevant to cytoskeleton and secreting neurotransmitters. The cell biological mechanism for treating AD by acupuncture might be achieved by improving synapse functions and promoting the secretion of neurotransmitters through transmembrane signal transduction, thus improving cognitive function of AD patients.

  13. Action growth for AdS black holes

    Science.gov (United States)

    Cai, Rong-Gen; Ruan, Shan-Ming; Wang, Shao-Jiang; Yang, Run-Qiu; Peng, Rong-Hui

    2016-09-01

    Recently a Complexity-Action (CA) duality conjecture has been proposed, which relates the quantum complexity of a holographic boundary state to the action of a Wheeler-DeWitt (WDW) patch in the anti-de Sitter (AdS) bulk. In this paper we further investigate the duality conjecture for stationary AdS black holes and derive some exact results for the growth rate of action within the Wheeler-DeWitt (WDW) patch at late time approximation, which is supposed to be dual to the growth rate of quantum complexity of holographic state. Based on the results from the general D-dimensional Reissner-Nordström (RN)-AdS black hole, rotating/charged Bañados-Teitelboim-Zanelli (BTZ) black hole, Kerr-AdS black hole and charged Gauss-Bonnet-AdS black hole, we present a universal formula for the action growth expressed in terms of some thermodynamical quantities associated with the outer and inner horizons of the AdS black holes. And we leave the conjecture unchanged that the stationary AdS black hole in Einstein gravity is the fastest computer in nature.

  14. Biomass valorisation by staged degasification A new pyrolysis-based thermochemical conversion option to produce value-added chemicals from lignocellulosic biomass

    NARCIS (Netherlands)

    de Wild, P. J.; den Uil, H.; Reith, J. H.; Kiel, J. H. A.; Heeres, H. J.

    2009-01-01

    Pyrolysis of lignocellulosic biomass leads to an array Of useful solid, liquid and gaseous products. Staged degasification is a pyrolysis-based conversion route to generate value-added chemicals from biomass. Because of different thermal stabilities of the main biomass constituents hemicellulose. ce

  15. The effect of adding group-based counselling to individual lifestyle counselling on changes in dietary intake. The Inter99 study--a randomized controlled trial

    DEFF Research Database (Denmark)

    Toft, Ulla; Kristoffersen, Lis; Ladelund, Steen;

    2008-01-01

    Few studies have investigated the specific effect of single intervention components in randomized controlled trials. The purpose was to investigate the effect of adding group-based diet and exercise counselling to individual life-style counselling on long-term changes in dietary habits....

  16. Disentangling location based mobile advertising: the effects of location congruence and type of the medium on consumers' ad-recall and buying behaviour

    NARCIS (Netherlands)

    Bernritter, S.; Ketelaar, P.; van Woudenberg, T.J.; Vantriet, J.; Huhn, A.; Janssen, L.

    2015-01-01

    An emerging body of research focuses on location-based advertising (LBA). This literature suggests that the merits of LBA rely on the fact that consumers can be targeted with location-congruent ads on their personal mobile devices. However, it has not yet been taken into account that LBA consists of

  17. A new multi-channel MAC protocol based on CDMA for ad hoc networks%一种基于CDMA的多信道自组网MAC协议

    Institute of Scientific and Technical Information of China (English)

    贾旻; 陈惠民; 袁玉华

    2007-01-01

    This paper proposes a novel multichannel medium access control (MAC) protocol based on CDMA that improves network performance and reduces collision probability in wireless ad hoc networks. In the scheme, the code channel is divided into common channel, broadcast channel and several data channels. Simulation results show that the proposed protocol can achieve significantly better performance than the IEEE 802.11 standard.

  18. 有向Ad hoc网络中一种基于DNAV包调度的多址接入协议%Novel directional-NAV-based packets scheduling for MAC protocol in directional antenna of Ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    崔苗; 石春; 曹英烈

    2011-01-01

    For directional antennas application in mobile Ad hoc networks, proposed a novel directional network allocation vector-based packets scheduling (DAPS) algorithm.The algorithm divided the surrounding region of the node using the DNAV parameters, and eliminated the region that was not available, lastly chose the ideal destination node to send the packet.Simulations results on OPNET environment explicitly show the DAPS scheme can enable higher throughput while effectively solving the HOL blocking problem.%移动Ad hoc网络中应用方向性天线,在增加网络吞吐量的同时会产生队列头阻塞问题(head of line blocking,HOL).提出一种基于有向网络分配矢量包调度的多址接入协议(directional network allocation vector-based packets scheduling for MAC protocol,DAPS),使用有向网络分配矢量(directional network allocation vector,DNAV)作为包调度的策略,将节点周边区域进行划分,在可用区域内选择理想目的数据包进行发送.利用OP-NET仿真软件对其进行了网络仿真,并在结果分析中验证了DAPS协议更适合网络拓扑结构的变化,且有效地解决了HOL问题和进一步提高了网络吞吐量.

  19. Identity-based cluster key agreement scheme in Ad Hoc network%Ad Hoc网络中基于身份的簇密钥协商机制

    Institute of Scientific and Technical Information of China (English)

    刘雪艳; 张强; 王彩芬

    2012-01-01

    针对Ad Hoc网络能源受限、动态变化的特性,提出一个基于身份的组密钥协商机制.该机制基于簇结构,允许同步执行基于对的多方密钥协商协议,从而使得簇成员数不影响密钥协商;密钥协商期间不需要交互,进而提供安全认证和动态性.在判定性双线性Diffie-Hellman( DBDH)问题下证明了该机制的语义安全性,并与已有方案在安全性、通信量和计算量方面进行了比较,结果表明所提机制在协商轮数和认证性方面具有优势.%In view of the characteristics of limited energy and dynamic change in Ad Hoc network, an identity-based group key agreement scheme was presented. The topology was in a structure composed by clusters, and allowed the synchronous execution of multi-party key agreement protocols based on pairings. The number of cluster members did not affect the key agreement, and it did not require interactivity during the key agreement. It provided the authentication and dynamics. In addition, the scheme was proved semantics secure under the Decisional Bilinear Diffie-Hellman (DBDH) problem. At last, compared with the previous schemes, the proposed scheme has advantages in terms of negotiation rounds and authentication.

  20. X-ray absorption fine structure analysis of molybdenum added to BaTiO3-based ceramics used for multilayer ceramic capacitors

    Science.gov (United States)

    Ogata, Yoichiro; Shimura, Tetsuo; Ryu, Minoru; Iwazaki, Yoshiki

    2017-04-01

    The effect of slight molybdenum doping of perovskite-type BaTiO3-based ceramics on the reliability of a multilayer ceramic capacitor (MLCC) and on the valence state of molybdenum in the BaTiO3-based ceramics has been investigated by highly accelerated lifetime tests and X-ray absorption fine structure analysis. The molybdenum added to the BaTiO3-based ceramics is located at Ti sites and improves the highly accelerated lifetime and lowers the initial dielectric resistivity in MLCCs. Through sintering in a reducing atmosphere, which is an important process in the fabrication of BaTiO3-based MLCCs, the oxidation state of the molybdenum added could be adjusted from +6 to a value close to +4.

  1. A stability and delay based routing protocol for cognitive radio Ad Hoc networks%认知 Ad-Hoc 网络中一种基于稳定性和时延的路由协议

    Institute of Scientific and Technical Information of China (English)

    朱江; 郭兵; 段昂

    2016-01-01

    In the future cognitive Ad-Hoc networks,the activities of the primary users will cause great influence on the sta-bility of multiple hops routes between cognitive users.To ensure the route stability and reduce the route latency between cognitive users,a stability and delay based routing protocol is proposed.In the protocol the concept of stability factor is in-troduced,only the paths under the stability constraint can be the candidate routes.Then the transmission delay is used as a metric to select the best route from those candidate routes.First,the superiority of the proposed routing selection strategy is demonstrated through a sample topology model.Then,the latency and route stability in cognitive radio Ad-Hoc networks are detailed analyzed.Last,improvements are made on the traditional AODV protocol to realize the proposed channel allocation and routing selection strategy.Simulation results show that the proposed protocol has a better performance on route stability and end to end delay both under different source and destination distances,and different primary user activities.%未来的认知 Ad-Hoc 网络中,授权用户的活动将对认知用户之间的多跳路由的稳定性造成很大影响,为了保证认知用户之间路由的稳定性并降低路由的端到端时延,提出了一种基于稳定性和时延的路由协议。该协议引入稳定性因子,只有满足了稳定性约束条件的路由才可以作为候选路由,然后将传输时延作为度量对候选路由进行筛选。通过一个简单拓扑模型验证了该路由选择策略的优越性;并针对认知无线 Ad-Hoc 网络的网络环境,分析了其时延和稳定性的模型,在此基础上结合传统 AODV(Ad hoc on-demand distance vector routing)路由协议,实现了提出的综合信道和路径选择策略。仿真结果表明:提出的路由协议无论在不同的源、目的节点距离,还是在不同的授权用户活跃程度下都具有更

  2. Berberine target key enzymes and amino acid inibitiors in AD treatment-----creation from berberine-based structure screening

    Directory of Open Access Journals (Sweden)

    Yau Lam

    2014-07-01

    Full Text Available The main components of berberine from coptis have a variety of pharmacological activity include the treatment of neurodegenerative diseases, Alzheimer’s disease (AD. The principle of berberine is inhibiting the lower activity of enzyme and amino acid to prevent (AD. Enzyme like acetylcholinesterase enzyme (AchE, butyrylcholinesterase enzyme (BchE and monoamine oxidase (MAO; Amino acid like beta-amyloid (Aβ. Unfortunately, the single chemical structures of berberine is no significance to regulation effect. As a part of our consideration, the review paper studies on chemically modified and synthesis from berberine-derivatives. Results show that the structures of (23, (10, (86, (52, and (61 have a potential effect for AchE, BuChE and Aβ-amyloid inhibitors for the first time. Especially in (23 and (52 also has better than two western medicine were compared.

  3. A Reliability-based Framework for Multi-path Routing Analysis in Mobile Ad-Hoc Networks

    CERN Document Server

    Caleffi, Marcello; Paura, Luigi

    2008-01-01

    Unlike traditional routing procedures that, at the best, single out a unique route, multi-path routing protocols discover proactively several alternative routes. It has been recognized that multi-path routing can be more efficient than traditional one mainly for mobile ad hoc networks, where route failure events are frequent. Most studies in the area of multi-path routing focus on heuristic methods, and the performances of these strategies are commonly evaluated by numerical simulations. The need of a theoretical analysis motivates such a paper, which proposes to resort to the terminal-pair routing reliability as performance metric. This metric allows one to assess the performance gain due to the availability of route diversity. By resorting to graph theory, we propose an analytical framework to evaluate the tolerance of multi-path route discovery processes against route failures for mobile ad hoc networks. Moreover, we derive a useful bound to easily estimate the performance improvements achieved by multi-pa...

  4. Influence of A/D Quantization in an Interpolated DFT Based System of Power Control with A Small Delay

    Directory of Open Access Journals (Sweden)

    Borkowski Józef

    2014-08-01

    Full Text Available Fast and accurate grid signal frequency estimation is a very important issue in the control of renewable energy systems. Important factors that influence the estimation accuracy include the A/D converter parameters in the inverter control system. This paper presents the influence of the number of A/D converter bits b, the phase shift of the grid signal relative to the time window, the width of the time window relative to the grid signal period (expressed as a cycle in range (CiR parameter and the number of N samples obtained in this window with the A/D converter on the developed estimation method results. An increase in the number b by 8 decreases the estimation error by approximately 256 times. The largest estimation error occurs when the signal module maximum is in the time window center (for small values of CiR or when the signal value is zero in the time window center (for large values of CiR. In practical applications, the dominant component of the frequency estimation error is the error caused by the quantization noise, and its range is from approximately 8×10-10 to 6×10-4.

  5. Segmented Strings in $AdS_3$

    CERN Document Server

    Callebaut, Nele; Samberg, Andreas; Toldo, Chiara

    2015-01-01

    We study segmented strings in flat space and in $AdS_3$. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In $AdS_3$, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an $AdS_2$ subspace of $AdS_3$. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We study several examples of closed segmented strings in $AdS_3$ and find an unexpected quasi-periodic behavior. We also work out a WKB analysis of quantum states of yo-yo strings in $AdS_3$ and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.

  6. Polarised black holes in AdS

    Science.gov (United States)

    Costa, Miguel S.; Greenspan, Lauren; Oliveira, Miguel; Penedones, João; Santos, Jorge E.

    2016-06-01

    We consider solutions in Einstein-Maxwell theory with a negative cosmological constant that asymptote to global AdS 4 with conformal boundary {S}2× {{{R}}}t. At the sphere at infinity we turn on a space-dependent electrostatic potential, which does not destroy the asymptotic AdS behaviour. For simplicity we focus on the case of a dipolar electrostatic potential. We find two new geometries: (i) an AdS soliton that includes the full backreaction of the electric field on the AdS geometry; (ii) a polarised neutral black hole that is deformed by the electric field, accumulating opposite charges in each hemisphere. For both geometries we study boundary data such as the charge density and the stress tensor. For the black hole we also study the horizon charge density and area, and further verify a Smarr formula. Then we consider this system at finite temperature and compute the Gibbs free energy for both AdS soliton and black hole phases. The corresponding phase diagram generalizes the Hawking-Page phase transition. The AdS soliton dominates the low temperature phase and the black hole the high temperature phase, with a critical temperature that decreases as the external electric field increases. Finally, we consider the simple case of a free charged scalar field on {S}2× {{{R}}}t with conformal coupling. For a field in the SU(N ) adjoint representation we compare the phase diagram with the above gravitational system.

  7. Study of the IDS in wireless Ad Hoc networks based on mobile agents%基于移动代理的无线Ad Hoc网络IDS研究

    Institute of Scientific and Technical Information of China (English)

    张念丽

    2006-01-01

    介绍了无线Ad Hoc网络的特点和面临的安全问题,分析了移动代理在Ad Hoc网络入侵检测系统中的适用性,给出了一种基于移动代理的无线Ad Hoc网络入侵检测系统模型.

  8. Research on Route Protocol of Ad hoc Network Based on Bluetooth Technology%基于蓝牙技术的Ad hoc自组网络路由协议

    Institute of Scientific and Technical Information of China (English)

    王曙; 刘永平

    2004-01-01

    基于蓝牙技术的Ad hoc网络是现阶段实现移动Ad hoc网络的便捷方案之一.讨论了基于蓝牙技术的移动Ad hoc网络设计实现过程中涉及的一些主要技术,并详细分析了蓝牙Ad hoc网络的路由结构设计、调度与性能.

  9. A Novel Routing Algorithm Based on ORF in Mobile Ad hoc Networks%基于最优路径函数的移动Ad hoc路由算法

    Institute of Scientific and Technical Information of China (English)

    刘字

    2011-01-01

    对于融合Ad hoc的新型网络,原有的Ad hoc网络路由策略也需要相应的改变,对路由影响比较关键的因素需要进行综合考虑.基于此,该文提出了一种最优路径函数概念,综合考虑影响路由链路寿命的三个因素:地理位置、移动速度和电池电量信息,将其作为最优路径函数的三个参数,利用基站的强大数据处理能力计算出通往目的节点的最优路径.同时,以最优路径函数作为路由切换的判断依据,实时更新路由状况,在路由质量变差时,将路由切换到质量较好的链路上.仿真结果表明能有效降低路由的中断率,提高系统路由的可靠性.%In the integrated network, due to the involvement of other networks, routing strategy needs to improve. It needs to consider the key factors whose influence is serious comprehensively. This paper proposes a novel concept of the optimal routing function and a method of using the base station to calculate the optimal path. The function includes three main parameters; location, mobility and buttery of mobile nodes, which are the key factors that affect complication of routing link. This paper also proposes a novel routing handover strategy based on the optimal routing function. The base station will calculate the optimal path all the time and decide to switch when the routing link becomes too poor. The routing handover strategy route will reduce the disruption rate and improve system routing reliability.

  10. Novel subtractive transcription-based amplification of mRNA (STAR method and its application in search of rare and differentially expressed genes in AD brains

    Directory of Open Access Journals (Sweden)

    Walker P Roy

    2006-11-01

    Full Text Available Abstract Background Alzheimer's disease (AD is a complex disorder that involves multiple biological processes. Many genes implicated in these processes may be present in low abundance in the human brain. DNA microarray analysis identifies changed genes that are expressed at high or moderate levels. Complementary to this approach, we described here a novel technology designed specifically to isolate rare and novel genes previously undetectable by other methods. We have used this method to identify differentially expressed genes in brains affected by AD. Our method, termed Subtractive Transcription-based Amplification of mRNA (STAR, is a combination of subtractive RNA/DNA hybridization and RNA amplification, which allows the removal of non-differentially expressed transcripts and the linear amplification of the differentially expressed genes. Results Using the STAR technology we have identified over 800 differentially expressed sequences in AD brains, both up- and down- regulated, compared to age-matched controls. Over 55% of the sequences represent genes of unknown function and roughly half of them were novel and rare discoveries in the human brain. The expression changes of nearly 80 unique genes were further confirmed by qRT-PCR and the association of additional genes with AD and/or neurodegeneration was established using an in-house literature mining tool (LitMiner. Conclusion The STAR process significantly amplifies unique and rare sequences relative to abundant housekeeping genes and, as a consequence, identifies genes not previously linked to AD. This method also offers new opportunities to study the subtle changes in gene expression that potentially contribute to the development and/or progression of AD.

  11. The Performance Evaluation of AODV-based and DSR-based Multi-radio Routing Protocols in Cognitive Radio Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Zamree Che-aron

    2013-07-01

    Full Text Available Due to the huge advancement of wireless technologies, the radio spectrum is one of the most heavily used and costly natural resources. Cognitive Radio (CR is a promising technology to solve the problem of radio spectrum shortage and spectrum underutilization by enabling unlicensed users to opportunistically access the available licensed bands in an intelligent and cautious manner. In Cognitive Radio Ad Hoc Networks (CRAHNs, which operate without centralized administration, the data routing is one of the most important issues to be taken into account and requires more study. In this study, we analyze and evaluate the performance of AODV-based and DSR-based multi-radio routing protocols (AODV-MR, extended DSR and MR-LQSR in CRAHN using simulations in NS-2. The metrics used for performance analysis are average throughput, average end-to-end delay and average jitter. From the simulation results, it is observed that the MR-LQSR protocol provides better performance in term of average throughput and gives smallest number of dropped packets. Whereas the extended DSR gives better results of average end-to-end delay and average jitter.

  12. Load balancing algorithm based on probability for Ad hoc networks%一种适用于Ad hoc网络的基于概率负载均衡算法

    Institute of Scientific and Technical Information of China (English)

    WANG Hua-dong; HOU Yan; WANG Feng-chun

    2014-01-01

    To resolve the problems of network congestion leading to high end-to-end delay and low throughput in MANET (mobile Ad hoc network),this paper proposed an algorithm of load-balancing based on probability. In this algorithm, nodes mapped the load state of n%为解决移动自组织网络(MANET)中网络拥塞导致的网络时延增大和吞吐量下降,提出一种基于概率的负载均衡算法,节点利用历史负载信息映射网络负载状态,用概率算法进行路由准入,从而完成负载均衡。基于历史状态的负载映射有效解决了分布式独立运算中存在的负载状态判断困难等问题,概率算法能有效克服门限准入法则存在的模糊判别问题,同时大量减少广播包的洪泛,节省信道资源。结合经典的按需路由协议,设计了H&P_DSR(history and probability based dynamic source routing)协

  13. Polarised Black Holes in AdS

    CERN Document Server

    Costa, Miguel S.; Oliveira, Miguel; Penedones, João; Santos, Jorge E.

    2016-01-01

    We consider solutions in Einstein-Maxwell theory with a negative cosmological constant that asymptote to global $AdS_{4}$ with conformal boundary $S^{2}\\times\\mathbb{R}_{t}$. At the sphere at infinity we turn on a space-dependent electrostatic potential, which does not destroy the asymptotic $AdS$ behaviour. For simplicity we focus on the case of a dipolar electrostatic potential. We find two new geometries: (i) an $AdS$ soliton that includes the full backreaction of the electric field on the $AdS$ geometry; (ii) a polarised neutral black hole that is deformed by the electric field, accumulating opposite charges in each hemisphere. For both geometries we study boundary data such as the charge density and the stress tensor. For the black hole we also study the horizon charge density and area, and further verify a Smarr formula. Then we consider this system at finite temperature and compute the Gibbs free energy for both $AdS$ soliton and black hole phases. The corresponding phase diagram generalizes the Hawkin...

  14. 基于TCP的Ad Hoc网络路由协议性能分析与仿真%The Study of Routing Protocol's Performance in Ad Hoc Network Based on TCP

    Institute of Scientific and Technical Information of China (English)

    刘树立; 冯玉宾

    2013-01-01

    文章简述了Ad Hoc网络的组网特点以及Ad Hoc网络中典型的AODV、DSDV和DSR路由协议.对于Ad Hoc网络分别采用不同的路由协议时在传输层使用TCP Reno协议传输数据进行了仿真,仿真结果的分析表明了按需路由在Ad Hoc网络环境下建立TCP连接时具有更好的性能.并进一步指出了Ad Hoc网络的研究方向.

  15. Energy generation for an ad hoc wireless sensor network-based monitoring system using animal head movement

    DEFF Research Database (Denmark)

    S. Nadimi, Esmaeil; Blanes-Vidal, Victoria; Jørgensen, Rasmus Nyholm

    2011-01-01

    The supply of energy to electronics is an imperative constraining factor to be considered during the design process of mobile ad hoc wireless sensor networks (MANETs). This influence is especially important when the MANET is deployed unattended or the wireless modules within the MANET are not eas......The supply of energy to electronics is an imperative constraining factor to be considered during the design process of mobile ad hoc wireless sensor networks (MANETs). This influence is especially important when the MANET is deployed unattended or the wireless modules within the MANET...... accessible; however, animal movement can be potentially used to generate energy. In this study, the head movements of individual sheep in a flock during grazing were monitored in order to investigate the amount of energy that can be generated by these movements. By applying the Lagrange–d’Alembert Principle...... to this problem, the equations of motion from each neck-mounted sensor as well as the amount of mechanical energy generated per time instant (each second) during upward and downward head movements were calculated. This resulted in the production of 857 mW and 1660 mW during the downward and upward movements...

  16. Enhanced Route Re-Construction Method for Associativity Based Routing Protocol for Mobile Ad hoc NETworks (MANET

    Directory of Open Access Journals (Sweden)

    Fawaz A.M. Masoud

    2006-01-01

    Full Text Available A mobile Ad-hoc NETwork (MANET is wireless network composed of mobile nodes that are dynamically and randomly located in such a manner that the interconnections between nodes are capable of changing on a continual basis. In order to facilitate communication within the network, a routing protocol is used to discover routes between nodes. The primary goal of such an ad-hoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. Route construction and maintenance should be done with a minimum of overhead and bandwidth consumption. The ABR is a source-initiated protocol and is working on the assumption of stable route from the source to the destination node. Maintenance for the route when the destination node moves will be performed in backtracking scheme starting from the immediate upstream node from the destination. If this process results in backtracking more than halfway to the source, it will discontinue and a new route request will be initiated from the source. In the case if the Source Node moves, then the Source Node will invoke a route reconstruction because the ABR is source-initiated protocol. This study presents an enhanced method for the route re-construction in case the source, the intermediate, or the destination node changes its location by giving more active role to the moving node in maintaining the established route.

  17. Optimization of Quality of Service (QoS framework for highway based Vehicular Ad-hoc Networks (VANETs

    Directory of Open Access Journals (Sweden)

    Wajahat Hussain

    2016-02-01

    Full Text Available The Vehicular Ad-hoc Network is a novel technology. It has the property of higher node mobility. Vehicular Adhoc networks offer wireless communications between vehicles themselves (V2V and between vehicles to the roadside units (V2R. The VANET is an active research area, as it has great prospective to enhance the road and vehicle safety, efficiency of traffic. Vehicular Ad-hoc Network not only just provides the safety applications, but also provides communication to the users. The QoS support in VANET is a challenge when the existing routing paths become no longer are available as a result of changes in the velocity and position of node, and distance between the vehicular nodes or network topology. In this study we designed a framework which provides us the facility to enhance various Quality of Service parameters, such as End to End Delay, throughput and packet loss ratio etc. The proposed model uses layered approach, deep classification as existed QoS components are further broken down and provides Quality of Experience to the users. NCTUns is used as simulation tool to build up simulations. After getting the results of simulation we carried out the performance analysis of various routing protocols. The simulation results indicate that the proposed scheme provides much better performance in terms of various QoS parameters like End to End Delay, throughput and packet loss ratio.

  18. Ad hoc系统中基于中断概率边界的博弈功率控制算法%Power control game based on outage bound probabilities in Ad hoc systems

    Institute of Scientific and Technical Information of China (English)

    蔡跃明; 喻的雄; 吴丹; 胡均权

    2011-01-01

    By analyzing the outage probability of the Ad hoc systems on Rayleigh fading channel, the upper bound and lower bound of the outage probability were given in this paper.Then two power control functions were designed based on these two bounds to seek the minimum transmit power for minimum upper bound and lower bound.The existence and uniqueness of the two functions were proved and the power updating algorithms proposed.In the end, the performance analysis of the convergence and power consumer of these two functions was shown by simulation.It can be found that if the power cost factor is set to the critical point at which the convergent property of LC (Cost function based on lower bound called LC for simplicity) can be sustained, then the minimum outage probability can be obtained and this approach can reduce the complexity better than using outage probability to design the cost function directly.%通过对瑞利衰落信道下Ad hoc系统中断概率的分析,给出了中断概率的上界和下界,并以此为依据设计出结构类型相似的2个博弈功率控制函数,从而求得中断概率最小时的功率发射值.同时证明了所设计的2个博弈功率控制函数的纳什均衡存在且唯一,并给出了获得纳什均衡的功率更新算法.仿真结果表明,提出的算法能够有效地逼近中断概率,且较DPC算法而言,可以通过设置不同的功率参数因子而获得更大的灵活性.

  19. Block aerial triangulation based on two flight levels ADS40 imagery data%利用双高度层ADS40影像进行区域网空中三角测量

    Institute of Scientific and Technical Information of China (English)

    丁启伟; 戴晨光; 刘亚璠; 万欢

    2012-01-01

    Aerial triangulation, which is the crucial part in the photogrammetry process, is a method to calculate the plane coordinates and elevation of the tie points and the exterior orientation parameters of the photo based on some amount control points. With the development of navigating and positioning technique, highly accurate POS system is equipped on the aerial aircraft to record the position and attitude of the camera at the shooting moment, which is used to support the aerial triangulation. In this paper, it used the two flight levels ADS40 imagery data, POS data and some ground control data to perform aerial triangulation based on ORIMA software. And finally the accuracy of the aerial triangulation with two flight levels imagery data was compared with that of the solo flight level imagery data.%空中三角测量是利用航摄像片与被摄目标之间的空间几何位置关系,根据少量的野外控制点,计算节点的平面坐标与高程以及航摄像片的外方位元素的方法,是摄影测量过程中的重要环节.随着导航定位技术的发展,高精度POS装置被广泛安装到航拍飞机上,用于记录航拍时刻相机的位置与姿态,从而进行辅助空中三角测量.本文研究利用双高度层的ADS40航线影像,结合POS数据,利用一定数量的控制点,基于ORIMA软件进行空中三角测量,并对其解算精度与同一区域单高度层航线影像的空三精度进行比较.

  20. Power Control Algorithm Based on Convex Optimization in Cognitive Ad hoc Networks%认知Ad hoc网络中基于凸优化的功率控制算法

    Institute of Scientific and Technical Information of China (English)

    胡图; 景志宏; 张磊; 张秋林

    2012-01-01

    Aimed at the characteristics of cognitive Ad hoc network, a corresponding network model is established and a distributed power control algorithm based on convex optimization theory is proposed. Based on the analysis of system interference, by taking the network utility maximization as the target and transmit power of cognitive user as the solution object, a general math optimized model is formulated. Under the guidance of convex optimization theory , the model is transformed into a convex optimized model by introducing auxiliary variable and substituting variables. Lagrangian dual decomposition technique is used to solve the convex optimized model and the distributed power iterative algorithm is obtained. The simulation shows that under the premise of meeting the system constraints, the use of the proposed algorithm can obtain better system performances than that of other algorithms.%针对认知Ad hoc网络的特点,构建了相应的网络模型,提出了一种基于凸优化理论的分布式功率控制算法.在分析系统内部干扰的基础上,以最大化网络效用值为目标,以认知用户的发射功率为求解对象,建立了一个通用的数学优化模型.在凸优化理论的指导下,通过引入辅助变量和变量的对数变换,将该模型转变为等价的凸优化模型,采用拉格朗日对偶法对该模型进行求解,得到了分布式的功率迭代算法.仿真实验表明:与其他算法相比,该算法在满足系统约束条件的前提下,取得更好的系统性能.

  1. Ad Hoc Network Video Transmission Based on Hybrid Flow Congestion Control%基于混合流拥塞控制的Ad Hoc网络视频传输

    Institute of Scientific and Technical Information of China (English)

    陈亮; 顾翔

    2015-01-01

    基于TCP反馈的主动队列管理算法会无差别地丢弃UDP分组,导致视频质量下降.根据TCP/UDP发送特性和混合流排队机制,推导拥塞窗口、丢弃概率及混合流队列长度的微分方程,通过线性化获得Ad Hoc网络混合流AQM(active queue management)控制模型,提出了一种减少UDP丢弃率的PI-V主动队列管理算法.当视频画质下降时,算法依据视频帧权重与分组长度,动态地调整UDP视频流的丢弃概率.NS(network simulator)仿真表明,PI-V算法优于PI与去尾算法,提高了视频传输质量0.82 dB~2.22 dB的峰值信噪比(PSNR).%An active queue management (AQM)algorithm,based on TCP feedback,will drop UDP packets indis-tinguishably,leading to a dropin UDP video quality.Congestion window-size,drop probability,and the dif-ferential equations of the hybrid flow queue length are deduced based on TCP/UDP transmission characteris-ticsand hybrid flow queuing mechanisms.An Ad Hoc network hybrid flow AQM control model is obtained through the linearization of these equations.A PI-V AQMalgorithm is proposed,which reduces the drop-rate of UDPs.This algorithm dynamically modifies the drop probability for UDP video stream,adjusting to video frame weight and packet length as the transmission quality changes.NS (network simulator)simulations dem-onstrate that this PI-V algorithm′s performance is better than that of the PI and drop-tail algorithms.The to-be-discussed PI-V AQMalgorithm improves video transmission quality by 0.82 dB-2.22 dB,as determined from the peak signal-to-noise ratio.

  2. Constructing Lifshitz solutions from AdS

    CERN Document Server

    Cassani, Davide

    2011-01-01

    Under general assumptions, we show that a gravitational theory in d+1 dimensions admitting an AdS solution can be reduced to a d-dimensional theory containing a Lifshitz solution with dynamical exponent z=2. Working in a d=4, N=2 supergravity setup, we prove that if the AdS background is N=2 supersymmetric, then the Lifshitz geometry preserves 1/4 of the supercharges, and we construct the corresponding Killing spinors. We illustrate these results in examples from supersymmetric consistent truncations of type IIB supergravity, enhancing the class of known 4-dimensional Lifshitz solutions of string theory. As a byproduct, we find a new AdS4 x S1 x T(1,1) solution of type IIB.

  3. The effect of adding group-based counselling to individual lifestyle counselling on changes in dietary intake. The Inter99 study – a randomized controlled trial

    OpenAIRE

    Smith Lisa; Pisinger Charlotta; Lau Cathrine; Ovesen Lars; Ladelund Steen; Kristoffersen Lis; Toft Ulla; Borch-Johnsen Knut; Jørgensen Torben

    2008-01-01

    Abstract Background Few studies have investigated the specific effect of single intervention components in randomized controlled trials. The purpose was to investigate the effect of adding group-based diet and exercise counselling to individual life-style counselling on long-term changes in dietary habits. Methods The study was a randomized controlled intervention study. From a general Danish population, aged 30 to 60 years (n = 61,301), two random sample were drawn (group A, n = 11,708; grou...

  4. An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent.

    Science.gov (United States)

    Sun, Xiao Qi; Peng, Bo; Chen, Ji; Li, De Qian; Luo, Fang

    2008-01-15

    Selective extraction-separation of yttrium(III) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim][PF(6)]/[Tf(2)N]-based extraction system without increasing the loss of [C(n)mim](+).

  5. Ad Hoc网络%Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    王海涛

    2005-01-01

    首先介绍了Ad Hoc网络的基本概念、技术特点以及关键技术等,然后较为全面地归纳了Ad Hoc网络的典型应用,最后讨论了Ad Hoc网络的发展趋势和有待解决的问题.

  6. IMPROVEMENT OF KEY PROCESSES THROUGH THE ANALYSIS OF VALUE ADDED IN TECHNOLOGY- BASED COMPANIES A SINGLE PROJECT PRODUCTIONS OF THE WATER SECTOR IN CUBA

    Directory of Open Access Journals (Sweden)

    Reina Maylín, Hernández Oro

    2012-01-01

    Full Text Available In this paper, we present the main results of research designed to improve key business processes, using a procedure designed for this purpose, and which includes among its main stages, the analysis of value added by activity, adapting to technology based companies’ productions by one of the water sector project in Cuba. The procedure consistently combines different techniques such as multi-criteria decision analysis for selection of the key processes and analysis of value added by activity to identify key processes to improve and identify opportunities for improvement. The main results are able to identify, classify and relate the processes taking place in the organization, and represent them in a process map, and then determine the key processes for improvement, based on the analysis of value added at each process of each of the activities in it. Derived from the results obtained are proposed and implemented a set of organizational improvements had a positive economic impact for the company under study, allowing a positive conclusion on the feasibility of implementation, flexibility and robustness of the procedure developed in technology-based companies single project productions of the water sector in Cuba to support their business management.

  7. ADS's Based on the 660 MeV Proton Phasotron of JINR for Research on Utilization of Plutonium

    CERN Document Server

    Barashenkov, V S; Puzynin, I V

    2000-01-01

    The operating in JINR (Dubna) 660 MeV phasotron with the proton beam intensity of 3.2 muA provides a way for building a safe ADS with the coefficient of neutron multiplication K_{eff}<0.95 and the heat power of 10-30 kW which is sufficient for experimental research on electronuclear technology. Such a simple and cheap set-up allows one to check up the basic ideas of the widely discussed new method of energy production and provides information which is important for designers of more powerful industrial ADSs. Two types of subcritical assemblies are considered: with weapon grade metallic plutonium rods and with standard MOX fuel rods (25 % PuO_2 + 75 % natural UO_2). A reflector with ^{9}Be allows one to decrease significantly the used amount of fuel.

  8. Reconstruction of precipitation in Morocco since 1100 A.D. Based on Cedrus atlantica tree-ring widths

    Science.gov (United States)

    Till, Claudine; Guiot, Joël

    1990-05-01

    Annual (October through September) precipitation from 1100 A.D. to modern times is reconstructed for Morocco, using Cedrus atlantica (Endl.) Carrière tree-ring chronologies. Both multiple regression on principal components and the bootstrap method are use to calibrate tree-ring width with precipitation; precipitation variation is reconstructed for three climatically distinct areas: the humid, subhumid, and arid regions of Morocco. A series of successive wet and dry periods is identified for the past 1000 years; the maximum length of the 13 dry periods (during which precipitation was at least 1σ below normal) is 6 years. Twenty-one years are identified during which precipitation fell more than 2σ below normal. We are unable to identify significant correspondence in climatic variation in Morocco, Europe, and the Sahel during this time period.

  9. A SURVEY ON SPECTRUM-MAP BASED ON NORMAL OPPORTUNISTIC ROUTING METHODS FOR COGNITIVE RADIO AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    Hesham Mohammed Ali Abdullah

    2015-11-01

    Full Text Available Cognitive Radio (CR technology has significant impacts on upper layer performance in Ad Hoc Networks (AHNs. In recent times, several number of investigation are conducted in CR are mostly focusing on the opportunistic spectrum admission and physical layer transmission throughput. However, CR technology determination also have considerable impacts in mobile Ad Hoc networks (AHNs, which enables wireless devices to dynamically create networks without essentially use of a fixed infrastructure . Nowadays, establishing a cognitive network is such a difficult task. The most important issues is routing in CRAHNs. In this paper, it majorly focuses on the survey of routing and opportunistic routing schema in CRAHN. The most significant scheme behind this concept is to make use of a suitable routing protocol designed for establishing Cognitive Radio Network (CRN. Due to licensing, the accessibility of radio frequency for wireless communication gets reduced day by day. Thus, there is a necessitate to have some other way to use these frequencies in an efficient manner. Routing is efficient method to solve these issues, but the use of geographical concept is also a challenging task in CRN. Since, there is a lack in detailed understanding of these extremely dynamic opportunistic links and a consistent end-to-end transportation mechanism over the network. Here, it focuses on the study of possible routing approaches with the purpose of be able to be employed in CRAHNs. There is a comparison on performance evaluation of various potential routing approaches in terms of table significant reduction and what solution can be found from the routing protocol are also discussed. The routing protocol attains reliable communications for CRAHNs, without usually getting feedback information from nodes in a CRAHN to considerably accumulate the communication overhead.

  10. 基于NS-2的Ad hoc网络路由协议性能研究%Research of performance for mobile Ad hoc networks routing protocol based on NS-2

    Institute of Scientific and Technical Information of China (English)

    钱开国

    2010-01-01

    移动Ad hoc是下一代网络(NGN)的重要组成部分,无需固定基础设施的临时网络.重点研究了目前典型的Ad hoc网络的路由协议,设计并实现了在NS-2环境下典型协议的仿真场景和性能分析比较.对Ad hoc路由协议的研究和组网具有参考指导意义.

  11. 基于Ad Hoc网络自愈合机制的创新研究%Ad Hoc Networks Based on Self-healing Mechanism of Innovative Research

    Institute of Scientific and Technical Information of China (English)

    文春生

    2011-01-01

    In the Ad Hoc network, the network connective lifetime caused by the constrained energy and the mobility of network nodes and the various efficiency of nodes represents its serf-healing properties. How to improve the serf-healing properties of Ad Hoc becomes the mushrooming concern. In this paper, to prolong the connectivity lifetime of Ad Hoc network and efficiency of each node, a new Ad Hoc network serf-healing mechanism design strategy is presented, which integrates the energy information of each node, routing information of Ad Hoc network and realtime information of GPS as input factors to achieve the extended network connectivity lifetime and improved network efficiency. Simulation results show that the new self-healing mechanism is feasible, it extends the connectivity lifetime of Ad Hoc Networks to nearly 10s, and the network efficiency is improved by 10%.%在Ad Hoc网络中,由网络节点的移动性及能源受限导致的网络连通寿命和各个节点效率的易变性,表现了网络的自愈合性能,如何提高Ad Hoc自愈合性能成为关注的问题.针对Ad Hoc网络的连通寿命和各个节点效率问题,为达到延长网络连通寿命和提高了网络效率的目的,提出了一种新的Ad Hoc网络自愈合机制设计策略,采用将各个节点的能源信息、Ad Hoc网络即时路由信息和GPS信息结合起来作为输入因素的方法.通过仿真计算,仿真结果显示,新的自愈合机制是可行的,能使Ad Hoc网络的连通寿命延长了近10s,网络效率提高了10%.

  12. An Improved Protocol of Ad Hoc Based on Multichannel Statistics on MAC Layer%一种基于多信道统计的Ad Hoc网络MAC层协议

    Institute of Scientific and Technical Information of China (English)

    卞东亮; 张红梅; 彭沙沙; 赵玉亭

    2013-01-01

    针对现代战场对新型数据链提高实时精确打击能力,在网络高负载时传输低延时的要求,以Ad Hoc网络为基础,其相应MAC层提出了一种基于多信道优先级统计的算法(PSMC).协议采用将优先级阈值与信道统计作对比的方式,判定数据是否发送.同时采用时槽、信元等机制保障数据发送的可靠性.PSMC协议能够保证数据的成功发送延时维持在极低水平,较好地满足各优先级业务的QoS,尤其对较高优先级的业务提供了实时、安全的保障;较之经典的ALOHA、Slotted ALOHA协议,结果表明PSMC协议可以承载较大的流量负荷,保证较高的吞吐量,甚至在网络超载的情况下,通过截流的方式仍然能够保障整个网络系统继续工作,不至于快速崩溃.%For improving real-time accurate strike capability and the low delay transmission in high traffic-load of new data link in the modern battlefield, the MAC layer adopts an improved algorithm named Priority Statistic based on Multichannel Access Method(PSMC )with Ad Hoc network as a basis. In the protocol the mode of comparing the priority threshold value with the channel occupancy statistics is adopted to determine whether to transmit the data or not. Also mini-slot and cell are adopted to protect data transmission reliability. Simulation results show that PSMC protocol can ensure that successful sending of data be maintained at the level of very low delay and satisfy the QoS of every Priority, especially provide real-time, safe guarantee for the high-priority. Compared to classic protocol of ALOHA, Slotted ALOHA, the results show that PSMC can carry heavy traffic load and ensure high throughput. Even in the case of overloading, it also can go on working with throttling back traffic.

  13. AdS orbifolds and Penrose limits

    Energy Technology Data Exchange (ETDEWEB)

    Alishahiha, Mohsen; Sheikh-Jabbari, Mohammad M.; Tatar, Radu

    2002-12-09

    In this paper we study the Penrose limit of AdS{sub 5} orbifolds. The orbifold can be either in the pure spatial directions or space and time directions. For the AdS{sub 5}/{Lambda} x S{sup 5} spatial orbifold we observe that after the Penrose limit we obtain the same result as the Penrose limit of AdS{sub 5} x S{sup 5}/{Lambda}. We identify the corresponding BMN operators in terms of operators of the gauge theory on R x S{sup 3}/{Lambda}. The semi-classical description of rotating strings in these backgrounds have also been studied. For the spatial AdS orbifold we show that in the quadratic order the obtained action for the fluctuations is the same as that in S{sup 5} orbifold, however, the higher loop correction can distinguish between two cases.

  14. Biomineralization behavior of a vinylphosphonic acid-based copolymer added with polymerization accelerator in simulated body fluid

    Directory of Open Access Journals (Sweden)

    Ryo Hamai

    2015-12-01

    Full Text Available Apatite-polymer composites have been evaluated in terms of its potential application as bone substitutes. Biomimetic processes using simulated body fluid (SBF are well-known methods for preparation of such composites. They are reliant on specific functional groups to induce the heterogeneous apatite nucleation and phosphate groups possess good apatite-forming ability in SBF. Improving the degree of polymerization is important for obtaining phosphate-containing polymers, because the release of significant quantities of monomer or low molecular weight polymers can lead to suppression of the apatite formation. To date, there have been very few studies pertaining to the effect of adding a polymerization accelerator to the polymerization reaction involved in the formation of these composite materials under physiological conditions. In this study, we have prepared a copolymer from triethylene glycol dimethacrylate and vinylphosphonic acid (VPA in the presence of different amounts of sodium p-toluenesulfinate (p-TSS as a polymerization accelerator. The effects of p-TSS on the chemical durability and apatite formation of the copolymers were investigated in SBF. The addition of 0.1–1.0 wt% of p-TSS was effective for suppressing the dissolution of the copolymers in SBF, whereas larger amount had a detrimental effect. A calcium polyvinylphosphate instead of the apatite was precipitated in SBF.

  15. Design and nutritional properties of potential functional frankfurters based on lipid formulation, added seaweed and low salt content.

    Science.gov (United States)

    López-López, I; Cofrades, S; Ruiz-Capillas, C; Jiménez-Colmenero, F

    2009-10-01

    The aim of this paper was to design and analyse the nutritional composition (fatty acid profile, cholesterol, mineral and amino acid content) of low-fat frankfurters enriched with n-3 polyunsaturated fatty acids (PUFA) (using algal oil to add 400mg of docosahexanoic acid - DHA/100g of product) as affected by the addition of seaweed (5.5% Himanthalia elongata) and the partial substitution (50%) of animal fat by olive oil (as a source of monounsaturated fatty acids - MUFA) or combinations of olive oil and seaweed. Reduction of NaCl level was also studied. The presence of algal oil produced frankfurters with high long-chain n-3 PUFA contents. The partial substitution of the pork fat by olive oil reduced (P<0.05) saturated fatty acids (SFA) and promoted (P<0.05) MUFA. A healthier lipid formulation (algal and olive oils and the reducing animal fat) produced a good balance of MUFA/SFA, PUFA/SFA and n-6/n-3 ratios. Although adding seaweed had little effect on the lipid and amino acid profiles of frankfurters, it does constitute a means to produce low-sodium products with important dietary fibre content, with better Na/K ratios and rich in Ca.

  16. Sustainable development of tyre char-based activated carbons with different textural properties for value-added applications.

    Science.gov (United States)

    Hadi, Pejman; Yeung, Kit Ying; Guo, Jiaxin; Wang, Huaimin; McKay, Gordon

    2016-04-01

    This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h.

  17. Tree-ring-based reconstruction of precipitation in the Bighorn Basin, Wyoming, since 1260 A.D

    Science.gov (United States)

    Gray, S.T.; Fastie, C.L.; Jackson, S.T.; Betancourt, J.L.

    2004-01-01

    Cores and cross sections from 79 Douglas fir (Pseudotsuga menziesii) and limber pine (Pinus flexilis) trees at four sites in the Bighorn Basin of north-central Wyoming and south-central Montana were used to develop a proxy for annual (June-June) precipitation spanning 1260-1998 A.D. The reconstruction exhibits considerable nonstationarity, and the instrumental era (post-1900) in particular fails to capture the full range of precipitation variability experienced in the past ???750 years. Both single-year and decadal-scale dry events were more severe before 1900. Dry spells in the late thirteenth and sixteenth centuries surpass both magnitude and duration of any droughts in the Bighorn Basin after 1900. Precipitation variability appears to shift to a higher-frequency mode after 1750, with 15-20-yr droughts becoming rare. Comparisons between instrumental and reconstructed values of precipitation and indices of Pacific basin variability reveal that precipitation in the Bighorn Basin generally responds to Pacific forcing in a manner similar to that of the southwestern United States (drier during La Nin??a events), but high country precipitation in areas surrounding the basin displays the opposite response (drier during El Nin??o events). ?? 2004 American Meteorological Society.

  18. Silver- and Zirconium-added ternary and quaternary TiAu based high temperature shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wadood, A., E-mail: abdul.wadood@ist.edu.pk [High Temperature Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Department of Materials Science and Engineering, Institute of Space Technology (IST), Near Rawat Toll Plaza, Islamabad (Pakistan); Yamabe-Mitarai, Y. [High Temperature Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2015-10-15

    Low strength in B2 phase, incomplete shape memory effect and high cost of Au are obstacles for the use of Ti–50Au as a high temperature shape memory alloy. We investigated the effects of partial substitution of Ti with Zr and Au with Ag in Ti–Au on phase constitution, phase transformation, and high temperature thermo-mechanical and shape memory properties. Partial substitution of Ti with Zr in Ti–50Au and Ti–40Au–10Ag was found to improve the thermo-mechanical and shape memory effect. However, partial substitution of Au with Ag in Ti–50Au and Ti–50Au–10Zr was found to have negligible effects. Reasons for such different behavior of Zr- and Ag-added Ti–Au alloys are considered. - Highlights: • Au, Ag and Ti, Zr belong to same group. Effects of partial substitution of Au with Ag and Ti with Zr in Ti–Au are investigated. • Zr was found more effective than Ag in improving shape memory and mechanical properties. • Same atomic size of Au and Ag and large size misfit b/w Ti and Zr atoms. • Ag resulted large amount of precipitation in Ti–Au.

  19. 车载Ad Hoc网络中基于移动网关的数据传输%MGF: Mobile Gateway Based Forwarding for Infrastructure-to-Vehicle Data Delivery in Vehicular Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    陈丽; 李治军; 姜守旭; 冯诚

    2012-01-01

    由于车载Ad hoc网络拓扑的动态变化及车载节点的快速移动,应用现有传输方法在其上进行Internet接入点向移动车辆(Infrastructure-to-Vehicle,I2V)数据传输时成功率较低,而且传输延迟高、延迟抖动大.为了解决这一问题,文中利用公交车路线固定、运行特征可预测、节点及线路分布稠密等特性,将公交车作为移动网关( Mobile Gateway,MG),提出了一种新的基于MG转发的I2V数据传输方法(Mobile Gateway based Forwarding,MGF).文中首先将公路网模型化为状态-空间图,再运用马尔可夫决策方法建立了一种基于MG转发的I2V数据传输优化模型,然后通过对模型求解得出I2V数据传输的最优转发决策,最优转发决策指的就是每个状态下对应的最优动作序列,最后在目的车辆行驶轨迹上选取满足传输成功率阈值,并使I2V传输延迟最小的路口节点作为数据包与目的车辆的最优汇聚节点,即目标节点.应用MGF方法,MG节点将以最优概率转发序列向目标节点转发数据包.文中利用模拟平台对MGF方法的传输性能进行了评估,结果表明该方法在满足传输成功率阈值前提下,能够获得最小传输延迟期望.理论分析同样也证明了该方法的有效性.%The highly dynamic topology and the rapid movement of destination node pose special challenges to Infrastructure-to-Vehicle (I2V) data delivery in Vehicular Ad Hoc Networks (VANET). Current data delivery methods are with the strong delay, the large jitter of delay and low delivery ratio for I2V data delivery. The paper investigates how to effectively utilize the prominent characteristic of buses, and proposes Mobile Gateway (MG) based Forwarding (MGF) that buses are installed as MG to forward data packet. To solve the problem that the paper models road network as a probabilistic state-space graph, in which applies the value iteration algorithm for the markov decision processing model to derive the

  20. Superradiant instability in AdS

    CERN Document Server

    Ganchev, Bogdan

    2016-01-01

    The phenomenon of superradiance in the context of asymptotically global AdS spacetimes is investigated with particular accent on its effect on the stability of the systems under consideration. To this end, the concept of an asymptotically AdS spacetime is explained, together with its implications on the boundary conditions at $\\mathcal{I}$, as well as the Newman-Penrose-Teukolsky formalism, whereby the Teukolsky master equation in a most general form for Kerr-AdS is given. Furthermore, work done in the cases of RN-AdS and Kerr-AdS is laid out in a concise manner, putting emphasis on the important steps taken in determining the endpoint of the superradiant instability in the two configurations. For the former this turns out to be a black hole with reduced charge and a static charged scalar condensate around it, whereas for the latter two of the more probable outcomes are presented, both of which imply a violation of one of the cosmic censorships.

  1. Directional delivery system based on network narrow ADs%基于网络窄告的定向投放系统

    Institute of Scientific and Technical Information of China (English)

    刘进军

    2012-01-01

    As a new mode of online advertising, narrow AD has some unique characteristics. In this article, the present situation of narrow AD is discussed. Because there are some problems in narrow AD, such as high cost of publication, poor credibility and so on, a directional delivery mode based on network narrow AD is put forward. The directional delivery model and the functional modules of prototype system were designed. In the system, the communication between Flash and Web Service is achieved by means of XML technology to realize the load of Flash products. The module of product database is realized by creating XML file of Flash product. The optimal delivery of narrow AD is realized by designing the matching algorithm of key words for narrow AD and customer websites. The directional delivery system with the functions of high-efficiency directed publication and animation playback through Ajax dynamic requests were designed and implemented.%窄告作为一种新型的网络广告模式,有其独特的特征.对窄告的现状进行分析,针对窄告的发布费用高、可信度差等问题提出了基于网络窄告的定向投放模式.设计了定向投放模型和系统各功能模块,通过XML技术来完成Flash与Web Service的通信,实现Flash产品的载入;通过建立Flash产品的XML文件来实现产品库模块;通过设计使用窄告与用户网站的关键词匹配算法实现窄告投放的最优化投放.设计并实现的定向投放系统具有定向投放、Ajax动态请求动画播放、效率高等特点.

  2. 基于 AODV路由协议的 Ad Hoc战术通信网络攻击研究%Research on network attack of Ad Hoc tactical communication based on AODV routing protocol

    Institute of Scientific and Technical Information of China (English)

    朱鲁军; 黄准; 钱太阳; 王芳; 苏抗

    2016-01-01

    The AODV protocol is a kind of Ad Hoc network routing protocols ,which is frequently used by the tactical communication network .For Ad Hoc network using the AODV protocol ,two kinds of routing attacks are put forward and the performance by using OPNET simulation is analyzed .Under these two kinds of attacks ,network performance indicators are observed ,such as the packet loss rate ,delay ,throughput .%AODV协议是目前战术通信网络使用的比较多的一种Ad Hoc网络路由协议。针对AODV协议下的Ad Hoc战术通信网络提出了两种路由攻击办法,并用OPNET 进行了仿真和性能分析。在这两种攻击模式下,观察Ad Hoc战术通信网络的丢包率、时延、吞吐量等网络性能指标。

  3. Boson Stars in AdS

    CERN Document Server

    Buchel, Alex; Lehner, Luis

    2013-01-01

    We construct boson stars in global Anti de Sitter (AdS) space and study their stability. Linear perturbation results suggest that the ground state along with the first three excited state boson stars are stable. We evolve some of these solutions and study their nonlinear stability in light of recent work \\cite{Bizon:2011gg} arguing that a weakly turbulent instability drives scalar perturbations of AdS to black hole formation. However evolutions suggest that boson stars are nonlinearly stable and immune to the instability for sufficiently small perturbation. Furthermore, these studies find other families of initial data which similarly avoid the instability for sufficiently weak parameters. Heuristically, we argue that initial data families with widely distributed mass-energy distort the spacetime sufficiently to oppose the coherent amplification favored by the instability. From the dual CFT perspective our findings suggest that there exist families of rather generic initial conditions in strongly coupled CFT ...

  4. AdS solutions through transgression

    Energy Technology Data Exchange (ETDEWEB)

    Donos, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Gauntlett, J.P. [Imperial College, London (United Kingdom). Blackett Lab.]|[Imperial College, London (United Kingdom). The Institute for Mathematical Sciences; Kim, Nakwoo [Kyung Hee Univ., Seoul (Korea). Dept. of Physics and Research Inst. of Basic Science

    2008-07-15

    We present new classes of explicit supersymmetric AdS{sub 3} solutions of type IIB supergravity with non-vanishing five-form flux and AdS{sub 2} solutions of D=11 supergravity with electric four-form flux. The former are dual to two-dimensional SCFTs with (0,2) supersymmetry and the latter to supersymmetric quantum mechanics with two supercharges. We also investigate more general classes of AdS{sub 3} solutions of type IIB supergravity and AdS{sub 2} solutions of D=11 supergravity which in addition have non-vanishing three-form flux and magnetic four-form flux, respectively. The construction of these more general solutions makes essential use of the Chern-Simons or ''transgression'' terms in the Bianchi identity or the equation of motion of the field strengths in the supergravity theories. We construct infinite new classes of explicit examples and for some of the type IIB solutions determine the central charge of the dual SCFTs. The type IIB solutions with non-vanishing three-form flux that we construct include a two-torus, and after two T-dualities and an S-duality, we obtain new AdS3 solutions with only the NS fields being non-trivial. (orig.)

  5. The Effect of Ad Libitum Consumption of a Milk-Based Liquid Meal Supplement vs. a Traditional Sports Drink on Fluid Balance After Exercise.

    Science.gov (United States)

    Baguley, Brenton; Zilujko, Jessica; Leveritt, Michael D; Desbrow, Ben; Irwin, Christopher

    2016-08-01

    The aim of this study was to compare the effect of ad libitum intake of a milk-based liquid meal supplement against a carbohydrate-electrolyte sports drink following exercise induced fluid loss. Seven male participants (age 22.3 ± 3.4 years, height 179.3 ± 7.9 cm, body mass 74.3 ± 7.3 kg; mean ± SD) completed 4 separate trials and lost 1.89 ± 0.44% body mass through moderate intensity exercise in the laboratory. After exercise, participants consumed ad libitum over 2 h a milk-based liquid meal supplement (Sustagen Sport) on two of the trials (S1, S2) or a carbohydrate-electrolyte sports drink (Powerade) on two of the trials (P1, P2), with an additional 1 hr observational period. Measures of body mass, urine output, gastrointestinal tolerance and palatability were collected throughout the recovery period. Participants consumed significantly more Powerade than Sustagen Sport over the 2 h rehydration period (P1 = 2225 ± 888 ml, P2 = 2602 ± 1119 mL, S1 = 1375 ± 711 mL, S2 = 1447 ± 857 ml). Total urine output on both Sustagen trails was significantly lower than the second Powerade trial (P2 = 1447 ± 656 ml, S1 = 153 ± 62 ml, S2 = 182 ± 118 mL; p fluid balance were observed between any of the drinks at the conclusion of each trial (P1 = -0.50 ±0. 46 kg, P2 = -0.40 ± 0.35 kg, S1 = -0.61 ± 0.74 kg, S2 = -0.45 ± 0.58 kg). Gastrointestinal tolerance and beverage palatability measures indicated Powerade to be preferred as a rehydration beverage. Ad libitum milk-based liquid meal supplement results in similar net fluid balance as a carbohydrate-electrolyte sports drink after exercise induced fluid loss.

  6. Teacher Education under Audit: Value-Added Measures,TVAAS, EdTPA and Evidence-Based Theory

    Science.gov (United States)

    Price, Todd Alan

    2014-01-01

    This article describes how evidence-based theory fuels an audit culture for teacher education in the USA, placing faculty under monitoring and surveillance, and severely constraining judgment, discretion, and professional decision-making. The national education reform efforts, Race to the Top and Common Core State Standards, demand fealty to…

  7. Adding Value to Education for Sustainability in Africa with Inquiry-Based Approaches in Open and Distance Learning

    Science.gov (United States)

    Pretorius, Rudi; Lombard, Andrea; Khotoo, Anisa

    2016-01-01

    Purpose: Inquiry-based approaches can potentially enrich sustainability learning in any educational context, more so in open and distance learning (ODL--perceived as theoretically inclined) and in regions of educational need (such as the Global South, of which Africa forms part). The purpose of this paper is to map the benefits and challenges of…

  8. Testing for Distortions in Performance Measures: An Application to Residual Income Based Measures like Economic Value Added

    NARCIS (Netherlands)

    Sloof, R.; van Praag, M.

    2015-01-01

    Distorted performance measures in compensation contracts elicit suboptimal behavioral responses that may even prove to be dysfunctional (gaming). This paper applies the empirical test developed by Courty and Marschke (2008) to detect whether the widely used class of Residual Income based performance

  9. Supergravity on $AdS_{5/4}$ x Hopf Fibrations and Conformal Field Theories

    CERN Document Server

    Halyo, E

    2000-01-01

    We obtain three and four dimensional conformal field theories with less than maximal supersymmetry by using their supergravity duals. These supergravity theories are type II on $AdS_5 \\times CP^2$, IIA on $AdS_4 \\times CP^3$, IIB on $AdS_5 \\times S^5/Z_k$ and D=11 supergravity on $AdS_4 \\times S^7/Z_k$. They are obtained from the spherically compactified ten and eleven dimensional theories by either Hopf reduction or by winding the U(1) fiber over the base.

  10. Supergravity on $AdS_{5/4} \\times$ Hopf Fibrations and Conformal Field Theories

    OpenAIRE

    1998-01-01

    We obtain three and four dimensional conformal field theories with less than maximal supersymmetry by using their supergravity duals. These supergravity theories are type II on $AdS_5 \\times CP^2$, IIA on $AdS_4 \\times CP^3$, IIB on $AdS_5 \\times S^5/Z_k$ and D=11 supergravity on $AdS_4 \\times S^7/Z_k$. They are obtained from the spherically compactified ten and eleven dimensional theories by either Hopf reduction or by winding the U(1) fiber over the base.

  11. An evidence-based definition of lifelong premature ejaculation: Report of the International Society for Sexual Medicine (ISSM) Ad Hoc Committee for the Definition of Premature Ejaculation

    DEFF Research Database (Denmark)

    McMahon, C.G.; Althof, S.E.; Waldinger, M.D.

    2008-01-01

    authority based rather than evidence based, and have no support from controlled clinical and/or epidemiological studies. Aim. The aim of this article is to develop a contemporary, evidence-based definition of PE. Methods. In August 2007, the International Society for Sexual Medicine (ISSM) appointed several...... international experts in PE to an Ad Hoc Committee for the Definition of Premature Ejaculation. The committee met in Amsterdam in October 2007 to evaluate the strengths and weaknesses of current definitions of PE, to critique the evidence in support of the constructs of ejaculatory latency, ejaculatory control...... and encourage ongoing research into the true prevalence of this disorder and the efficacy of new pharmacological and psychological treatments Udgivelsesdato: 2008...

  12. Unsupervised learning in persistent sensing for target recognition by wireless ad hoc networks of ground-based sensors

    Science.gov (United States)

    Hortos, William S.

    2008-04-01

    In previous work by the author, effective persistent and pervasive sensing for recognition and tracking of battlefield targets were seen to be achieved, using intelligent algorithms implemented by distributed mobile agents over a composite system of unmanned aerial vehicles (UAVs) for persistence and a wireless network of unattended ground sensors for pervasive coverage of the mission environment. While simulated performance results for the supervised algorithms of the composite system are shown to provide satisfactory target recognition over relatively brief periods of system operation, this performance can degrade by as much as 50% as target dynamics in the environment evolve beyond the period of system operation in which the training data are representative. To overcome this limitation, this paper applies the distributed approach using mobile agents to the network of ground-based wireless sensors alone, without the UAV subsystem, to provide persistent as well as pervasive sensing for target recognition and tracking. The supervised algorithms used in the earlier work are supplanted by unsupervised routines, including competitive-learning neural networks (CLNNs) and new versions of support vector machines (SVMs) for characterization of an unknown target environment. To capture the same physical phenomena from battlefield targets as the composite system, the suite of ground-based sensors can be expanded to include imaging and video capabilities. The spatial density of deployed sensor nodes is increased to allow more precise ground-based location and tracking of detected targets by active nodes. The "swarm" mobile agents enabling WSN intelligence are organized in a three processing stages: detection, recognition and sustained tracking of ground targets. Features formed from the compressed sensor data are down-selected according to an information-theoretic algorithm that reduces redundancy within the feature set, reducing the dimension of samples used in the target

  13. GaAs multibit delta-sigma A/D converters based upon a new comparator design

    Energy Technology Data Exchange (ETDEWEB)

    Hickling, R.M.; Yagi, M.N.; Salman, H.H. [TechnoConcepts, Inc., Newbury Park, CA (United States)

    1995-12-31

    In this paper, the design of multibit delta-sigma converters based upon a new comparator bank structure is described. The comparator bank approach (patent pending) eliminates the need for comparator threshold terminals, allowing each of the individual latched comparators to operate upon the same differential input signal. This new comparator design was incorporated into a complete four-bit delta-sigma modulator which was fabricated on a 0.6{mu}m GaAs MESFET process.

  14. Conveyor Performance based on Motor DC 12 Volt Eg-530ad-2f using K-Means Clustering

    Science.gov (United States)

    Arifin, Zaenal; Artini, Sri DP; Much Ibnu Subroto, Imam

    2017-04-01

    To produce goods in industry, a controlled tool to improve production is required. Separation process has become a part of production process. Separation process is carried out based on certain criteria to get optimum result. By knowing the characteristics performance of a controlled tools in separation process the optimum results is also possible to be obtained. Clustering analysis is popular method for clustering data into smaller segments. Clustering analysis is useful to divide a group of object into a k-group in which the member value of the group is homogeny or similar. Similarity in the group is set based on certain criteria. The work in this paper based on K-Means method to conduct clustering of loading in the performance of a conveyor driven by a dc motor 12 volt eg-530-2f. This technique gives a complete clustering data for a prototype of conveyor driven by dc motor to separate goods in term of height. The parameters involved are voltage, current, time of travelling. These parameters give two clusters namely optimal cluster with center of cluster 10.50 volt, 0.3 Ampere, 10.58 second, and unoptimal cluster with center of cluster 10.88 volt, 0.28 Ampere and 40.43 second.

  15. Modeling and Analysis of Energy Conservation Scheme Based on Duty Cycling in Wireless Ad Hoc Sensor Network

    Directory of Open Access Journals (Sweden)

    Yun Won Chung

    2010-06-01

    Full Text Available In sensor network, energy conservation is one of the most critical issues since sensor nodes should perform a sensing task for a long time (e.g., lasting a few years but the battery of them cannot be replaced in most practical situations. For this purpose, numerous energy conservation schemes have been proposed and duty cycling scheme is considered the most suitable power conservation technique, where sensor nodes alternate between states having different levels of power consumption. In order to analyze the energy consumption of energy conservation scheme based on duty cycling, it is essential to obtain the probability of each state. In this paper, we analytically derive steady state probability of sensor node states, i.e., sleep, listen, and active states, based on traffic characteristics and timer values, i.e., sleep timer, listen timer, and active timer. The effect of traffic characteristics and timer values on the steady state probability and energy consumption is analyzed in detail. Our work can provide sensor network operators guideline for selecting appropriate timer values for efficient energy conservation. The analytical methodology developed in this paper can be extended to other energy conservation schemes based on duty cycling with different sensor node states, without much difficulty.

  16. Modeling and analysis of energy conservation scheme based on duty cycling in wireless ad hoc sensor network.

    Science.gov (United States)

    Chung, Yun Won; Hwang, Ho Young

    2010-01-01

    In sensor network, energy conservation is one of the most critical issues since sensor nodes should perform a sensing task for a long time (e.g., lasting a few years) but the battery of them cannot be replaced in most practical situations. For this purpose, numerous energy conservation schemes have been proposed and duty cycling scheme is considered the most suitable power conservation technique, where sensor nodes alternate between states having different levels of power consumption. In order to analyze the energy consumption of energy conservation scheme based on duty cycling, it is essential to obtain the probability of each state. In this paper, we analytically derive steady state probability of sensor node states, i.e., sleep, listen, and active states, based on traffic characteristics and timer values, i.e., sleep timer, listen timer, and active timer. The effect of traffic characteristics and timer values on the steady state probability and energy consumption is analyzed in detail. Our work can provide sensor network operators guideline for selecting appropriate timer values for efficient energy conservation. The analytical methodology developed in this paper can be extended to other energy conservation schemes based on duty cycling with different sensor node states, without much difficulty.

  17. TOWARD CALIBRATED MODULAR WIRELESS SYSTEM BASED AD HOC SENSORS FOR IN SITU LAND SURFACE TEMPERATURE MEASUREMENTS AS SUPPORT TO SATELLITE REMOTE SENSING

    Directory of Open Access Journals (Sweden)

    ASAAD CHAHBOUN

    2011-06-01

    Full Text Available This paper presents a new method for in situ Land Surface Temperature (LST measurements' campaigns for satellite algorithms validations. The proposed method based on Wireless Sensor Network (WSN is constituted by modules of node arrays. Each of which is constituted by 25 smart nodes scattered throughout a target field. Every node represents a Thermal Infra Red (TIR radiation sensor and keeps a minimum size while ensuring the functions of communication, sensing, and processing. This Wireless-LST (Wi-LST system is convenient to beinstalled on a field pointing to any type of targets (e.g. bare soil, grass, water, etc.. Ad hoc topology is adopted among the TIR nodes with multi-hop mesh routing protocol for communication, acquisition data are transmitted to the client tier wirelessly. Using these emergent technologies, we propose a practical method for Wi-LSTsystem calibration. TIR sensor (i.e. OSM101 from OMEGA society measures temperature, which is conditioned and amplified by an AD595 within a precision of 0.1 °C. Assessed LST is transmitted over thedeveloped ad hoc WSN modules (i.e. MICA2DOT from CROSSBOW society, and collected at in situ base station (i.e. PANASONIC CF19 laptop using an integrated database. LST is evaluated with a polynomialalgorithm structure as part of developed software. Finally, the comparison of the mean values of LST(Wi-LST in each site with the Moderate Resolution Imaging Spectro-radiometer (MODIS sensor, obtained from the daily LST product (MOD11C1 developed by the MODIS-NASA Science Team, on board TERRA satellite during the campaign period is provided.

  18. Refined Holographic Entanglement Entropy for the AdS Solitons and AdS black Holes

    CERN Document Server

    Ishihara, Masafumi; Ning, Bo

    2012-01-01

    We consider the refinement of the holographic entanglement entropy on a disk region for the holographic dual theories to the AdS solitons and AdS black holes, including the corrected ones by the Gauss-Bonnet term. The AdS soliton is dual to a gapped system with an IR fixed-point. The refinement is obtained by extracting the UV-independent piece of the holographic entanglement entropy. We then study the renormalization group (RG) flow of the refinement by tuning the linear size of the chosen disk region. Our main results are (i) the RG flow of the refinement decreases monotonically for most of the cases; (ii) there is no topological entanglement entropy for AdS$_5$ soliton even with Gauss-Bonnet correction; (iii) for the AdS black holes, the refinement obeys the volume law at IR regime, and the transition between UV and IR regimes is a smooth crossover; however, the crossover will turn into phase transition by the Gauss-Bonnet correction; (iv) for the AdS solitons, there are discontinuous phase transitions bet...

  19. Predicting AD conversion

    DEFF Research Database (Denmark)

    Liu, Yawu; Mattila, Jussi; Ruiz, Miguel �ngel Mu�oz

    2013-01-01

    To compare the accuracies of predicting AD conversion by using a decision support system (PredictAD tool) and current research criteria of prodromal AD as identified by combinations of episodic memory impairment of hippocampal type and visual assessment of medial temporal lobe atrophy (MTA) on MRI...

  20. Universal isolation in the AdS landscape

    Science.gov (United States)

    Danielsson, U. H.; Dibitetto, G.; Vargas, S. C.

    2016-12-01

    We study the universal conditions for quantum nonperturbative stability against bubble nucleation for pertubatively stable AdS vacua based on positive energy theorems. We also compare our analysis with the preexisting ones in the literature carried out within the thin-wall approximation. The aforementioned criterion is then tested in two explicit examples describing massive type IIA string theory compactified on S3 and S3×S3, respectively. The AdS landscape of both classes of compactifications is known to consist of a set of isolated points. The main result is that all critical points respecting the Breitenlohner-Freedman (BF) bound also turn out be stable at a nonperturbative level. Finally, we speculate on the possible universal features that may be extracted from the above specific examples.

  1. An AdS Crunch in Supergravity

    Science.gov (United States)

    Hertog, Thomas

    2004-12-01

    We review some properties of N=8 gauged supergravity in four dimensions with modified, but AdS invariant boundary conditions on the m2 = -2 scalars. There is a one-parameter class of asymptotic conditions on these fields and the metric components, for which the full AdS symmetry group is preserved. The generators of the asymptotic symmetries are finite, but acquire a contribution from the scalar fields. For a large class of such boundary conditions, we find there exist black holes with scalar hair that are specified by a single conserved charge. Since Schwarschild-AdS is a solution too for all boundary conditions, this provides an example of black hole non-uniqueness. We also show there exist solutions where smooth initial data evolve to a big crunch singularity. This opens up the possibility of using the dual conformal field theory to obtain a fully quantum description of the cosmological singularity, and we report on a preliminary study of this.

  2. EFFECT OF CLUSTERING IN DESIGNING A FUZZY BASED HYBRID INTRUSION DETECTION SYSTEM FOR MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    D. Vydeki

    2013-01-01

    Full Text Available Intrusion Detection System (IDS provides additional security for the most vulnerable Mobile Adhoc Networks (MANET. Use of Fuzzy Inference System (FIS in the design of IDS is proven to be efficient in detecting routing attacks in MANETs. Clustering is a vital means in the detection process of FIS based hybrid IDS. This study describes the design of such a system to detect black hole attack in MANET that uses Adhoc On-Demand Distance Vector (AODV routing protocol. It analyses the effect of two clustering algorithms and also prescribes the suitable clustering algorithm for the above-mentioned IDS. MANETs with various traffic scenarios were simulated and the data set required for the IDS is extracted. A hybrid IDS is designed using Sugeno type-2 FIS to detect black hole attack. From the experimental results, it is derived that the subtractive clustering algorithm produces 97% efficient detection while FCM offers 91%. It has been found that the subtractive clustering algorithm is more fit and efficient than the Fuzzy C-Means clustering (FCM for the FIS based detection system.

  3. Membrane-based energy efficient dewatering of microalgae in biofuels production and recovery of value added co-products.

    Science.gov (United States)

    Bhave, Ramesh; Kuritz, Tanya; Powell, Lawrence; Adcock, Dale

    2012-05-15

    The objective of this paper is to describe the use of membranes for energy efficient biomass harvesting and dewatering. The dewatering of Nannochloropsis sp. was evaluated with polymeric hollow fiber and tubular inorganic membranes to demonstrate the capabilities of a membrane-based system to achieve microalgal biomass of >150 g/L (dry wt.) and ∼99% volume reduction through dewatering. The particle free filtrate containing the growth media is suitable for recycle and reuse. For cost-effective processing, hollow fiber membranes can be utilized to recover 90-95% media for recycle. Tubular membranes can provide additional media and water recovery to achieve target final concentrations. Based on the operating conditions used in this study and taking into scale-up considerations, an integrated hollow fiber-tubular membrane system can process microalgal biomass with at least 80% lower energy requirement compared to traditional processes. Backpulsing was found to be an effective flux maintenance strategy to minimize flux decline at high biomass concentration. An effective chemical cleaning protocol was developed for regeneration of fouled membranes.

  4. A CONTEXT AWARE BASED PRE-HANDOFF SUPPORT APPROACH TO PROVIDE OPTIMAL QOS FOR STREAMING APPLICATIONS OVER VEHICULAR AD HOC NETWORKS – HOSA

    Directory of Open Access Journals (Sweden)

    K. RAMESH BABU

    2015-06-01

    Full Text Available Large variations in network Quality of Service (QoS such as bandwidth, latency, jitter, and reliability may occur during media transfer over vehicular ad hoc networks (VANET. Usage of VANET over mobile and wireless computing applications experience “bursty” QoS behavior during the execution over distributed network scenarios. Applications such as streaming media services need to adapt their functionalities to any change in network status. Moreover, an enhanced software platform is necessary to provide adaptive network management services to upper software components. HOSA, a handoff service broker based architecture for QoS adaptation over VANET supports in providing awareness. HOSA is structured as a middleware platform both to provide QoS awareness to streaming applications as well to manage dynamic ad hoc network resources with support over handoff in an adaptive fashion. HOSA is well analyzed over routing schemes such as TIBSCRPH, SIP and ABSRP where performance of HOSA was measured using throughput, traffic intensity and end to end delay. HOSA has been analyzed using JXTA development toolkit over C++ implemented classes to demonstrate its performance over varying node mobility established using vehicular mobility based conference application.

  5. 'Getting back to normal': the added value of an art-based programme in promoting 'recovery' for common but chronic mental health problems.

    Science.gov (United States)

    Makin, Sally; Gask, Linda

    2012-03-01

    OBJECTIVES. The aim of this project was to explore the added value of participation in an Arts on Prescription (AoP) programme to aid the process of recovery in people with common but chronic mental health problems that have already undergone a psychological 'talking'-based therapy. METHODS. The study utilized qualitative in-depth interviews with 15 clients with persistent anxiety and depression who had attended an 'AoP' service and had previously received psychological therapy. RESULTS and discussion. Attending AoP aided the process of recovery, which was perceived by participants as 'returning to normality' through enjoying life again, returning to previous activities, setting goals and stopping dwelling on the past. Most were positive about the benefits they had previously gained from talking therapies. However, these alone were not perceived as having been sufficient to achieve recovery. The AoP offered some specific opportunities in this regard, mediated by the therapeutic and effect of absorption in an activity, the specific creative potential of art, and the social aspects of attending the programme. CONCLUSIONS. For some people who experience persistent or relapsing common mental health problems, participation in an arts-based programme provides 'added value' in aiding recovery in ways not facilitated by talking therapies alone.

  6. 基于VBM-DARTEL的AD脑萎缩特征检测方法%Detection of brain atrophy in AD based on VBM-DARTEL method

    Institute of Scientific and Technical Information of China (English)

    卓芝政; 苑桂红; 李海云

    2014-01-01

    Objective To investigate the brain grey matter atrophy in Alzheimer disease (AD)and mild cognitive impairment (MCI ), and provide a detective method for exploring the evolution mechanism of AD.Methods By combining voxel based morphometry (VBM) and diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL),we firstly register and segment three T1 structural MRI datasets of 58 normal control (NC),40 AD patients,72 MCI patients including 26 progressive MCI (PMCI)patients and 46 stable MCI (SMCI ) patients.Then a specific template is built by using DARTEL method.Through deformation fields,the grey matter images are registered to MNI space with preserving the total amount of voxels by applying modulation method.Finally,statistical analysis is made on the processed datasets with two sample t test (P≤0.005,uncorrected).Results Compared to NC,the atrophy regions in AD mainly locate in the bilateral temporal lobe, the bilateral hippocampus and parahippocampal gyrus,the bilateral amygdala,the bilateral insula,the left middle occipital gyrus,the left precuneus,the left posterior cingulate gyrus.The atrophy regions in MCI locate in the bilateral putamen,the left amygdale and the left hippocampus.The atrophy regions in PMCI locate in the left putamen,the left amygdala and the left hippocampus.There is no atrophy region found in SMCI. Compared to MCI,the atrophy regions in AD are the bilateral temporal lobe,the bilateral hippocampus,the bilateral precuneus,the bilateral middle frontal gyrus,the left cingulate gyrus,the left insula,the right amygdala,the right parahippocampal gyrus,the right superior parietal gyrus.There is no atrophy region in MCI compared to AD. Compared to SMCI, the atrophy region in PMCI is in left inferior temporal gyrus,yet there is no atrophy region found in SMCI compared to PMCI. Conclusions VBM-DARTEL based method can achieve a more accurate registration of MRI images and detect subtle volume changes of cerebral grey matter

  7. Tree-ring based PDSI reconstruction since AD 1842 in the Ortindag Sand Land, east Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on three Chinese pine (Pinus tabulaeformis Carr.) and one Meyer spruce (Picea meyeri Rehd. et Wils.) ring-width chronologies, a 163-year drought history was reconstructed in the eastern Ortindag Sand Land. All tree-ring chronologies show large inter-annual variations and strong common signals and fairly consistent variation between different chronologies, indicating that they are excellent proxy of regional climate. A regional chronology (RC) was established by averaging the four standard chronologies and further employed for the analysis and climatic reconstruction. The analysis revealed that tree growth is primarily limited by low precipitation in February-March and June-July and high temperature in May-July. In addition, RC has high correlations with the monthly Palmer drought severity index (PDSI) prior to and during the growing season because the PDSI considers the accumulation of the droughts. Response function analysis revealed that RC only exhibits significant correlations with the PDSI in June and July (close to the 95% significance level in May). Because May―July is a critical period for tree growth, the average May-July PDSI (PDSI5-7) was reconstructed back to 1842 using RC in the Ortindag Sand Land. The reconstruction can explain 52% of the PDSI variance and the equation was rather stable over time. It agrees well with the variation of the average dryness/wetness indices in North China,and captures the decline process of the East Asian summer monsoon since the mid-1960s. It is worth noting that the Ortindag Sand Land has experienced the most severe drought in the recent 40 years based on the 163-year drought reconstruction. Like summer precipitation in North China the reconstructed PDSI5-7 also displays a 20-year oscillation.

  8. Adding more value to added-value

    DEFF Research Database (Denmark)

    Marian, Livia

    regulation. The results of a qualitative concept test reveal positive attitudes towards the proposed production process. The discussions about fewer standards being sufficient or about options “in-between” conventional and organic standards indicate that the difference in production processes is noticed, yet...... it is probably valued less than expected. The added attributes need to be thoroughly considered when developing and marketing “organic plus” products, as their effect on other product characteristics (e.g. high prices) can detract from their added value....

  9. Design and realization of HART protocol telecommunication module based on A5191HRT and AD421%基于A5191HRT和AD421的HART协议通信模块的设计与实现

    Institute of Scientific and Technical Information of China (English)

    顾伟; 费元春; 周建明

    2004-01-01

    首先叙述HART通信协议的发展和协议的层次结构,针对某现场仪表的HART协议远程通信模块的设计与实现的要求,完成了基于HART调制解调器A5191HRT和电流环数模转换器AD421的HART协议通信模块的软硬件设计.

  10. 基于AD7655的鱼雷声靶数据采集系统设计分析%Analysis for the Design of the Data Acquisition System of Torpedo Acoustics-Drone Based on AD7655

    Institute of Scientific and Technical Information of China (English)

    王楠

    2010-01-01

    为了保证鱼雷声靶工作时的可靠性和稳定性,数据采集系统必须具有多通道和高采样频率的特点,以满足高精度的试验要求.本文在分析鱼雷声靶数据采集系统的总体构成的基础上,介绍了运用高性能模数转换芯片AD7655实现数据采集系统的模数转换过程,说明了利用FPGA产生控制信号实现AD7655模数转换功能,以及AD7655与数字处理器传送数据的接口设计.在实际应用过程中证明,该系统的设计是合理的.

  11. Numerical Simulation of Flood Events of Truckee River in Nevada of USA Based on AdH Model%基于AdH模型的美国内华达州塔基河洪水数值模拟

    Institute of Scientific and Technical Information of China (English)

    陈孝兵; 赵坚; 陈力

    2014-01-01

    以美国内华达州塔基河为例,基于AdH模型建立了覆盖主槽和洪泛区的有限元数值模型,选取四种不同频率的洪水事件作为基础资料并对其洪水过程进行了模拟分析,探讨了输入参数对模拟结果的影响,并对AdH模型进行了率定和验证,进而分析了淹没面积和淹没体积与流量的关系.结果表明,主槽糙率系数的选取对洪水模拟结果的影响相对于洪泛区而言更为显著,是模型率定时应优先调整的参数;AdH模型完全可以再现洪水发展—消退的全过程,是一种有效的洪水预报模型;淹没面积和淹没体积与流量间的关系具有明显的反绳套规律.

  12. Simulation Study of UHF Low Noise Amplifier Based on ADS%基于ADS的UHF低噪声放大器仿真研究

    Institute of Scientific and Technical Information of China (English)

    唐德民

    2012-01-01

    从放大器电路、放大器芯片的S参数扫描、阻抗匹配特性,分析低噪声放大器的外围器件参数设计原理,采用ADS仿真软件实例研究基于MAX2640的低噪声放大器电路设计过程,提出综合考虑增益、噪声系数和阻抗匹配的方法。%The design principle of peripheral devices parameters of low noise amplifier is analyzed based on amplifier cir- cuit and S parameter of amplifier chip and impedance matching. The design process ofMAX2640-based LNA circuit is studied using ADS simulation software. Signal gain, noise coefficient and impedance matching are considered in design.

  13. U.S. Biomass Opportunities for Value-added Biomass Exports based on the European Union Renewable Energy Share Targets

    Directory of Open Access Journals (Sweden)

    Ulises Lacoa

    2014-10-01

    Full Text Available World energy demand is expected to continue increasing in the coming years. This situation has created a worldwide pressure for the development of alternative fuel and energy sources, pursuing a more environmentally friendly usage of biofuels. The EU has the target of generating 20% of its energy consumption from renewable sources by 2020. Member States have different individual targets to meet this overall target. Meanwhile in the United States, there are about 750 million acres [300 million hectares] of forestland, with slightly more than two-thirds classified as timberland or land capable of producing 20 cubic feet per acre [1.4 m3 per hectare] annually of roundwood. Given these circumstances, this research aimed to understand the U.S. opportunities to export woody biomass based on the targets that the European Union has imposed to its Member States. The data collected allowed several scenario developments by identifying the possible EU’s biomass deficits and U.S.’s capacity to supply the gaps. Considering the physical availability, the U.S. would be able to satisfy between 42 and 48% depending on the energy efficiency scenario. Nevertheless, when considering reasonable biomass prices, only a small portion of the EU demand could be covered by the U.S.

  14. Laser clad Ni-base alloy added nano- and micron-size CeO 2 composites

    Science.gov (United States)

    Zhang, Shi Hong; Li, Ming Xi; Cho, Tong Yul; Yoon, Jae Hong; Lee, Chan Gyu; He, Yi Zhu

    2008-07-01

    Micron-size Ni-base alloy (NBA) powders are mixed with both 1.5 wt% (%) micron-CeO 2 (m-CeO 2) and also 1.0-3.0% nano-CeO 2 (n-CeO 2) powders. These mixtures are coated on low carbon steel (Q235) by 2.0 kW CO 2 laser cladding. The effects on microstructures, microhardness and wear resistance of the coating by the addition of m- and n-CeO 2 powders to NBA (m- and n-CeO 2/NBA) have been investigated. Addition to the primary phases of γ-Ni, Cr 23C 6 and Ni 3B of NBA coating, CeNi 3 shows up both in m- and n-CeO 2/NBA coatings and CeNi 5 appears only in n-CeO 2/NBA coating. Directional dendrite and coarse equiaxed dendrite are grown in m-CeO 2/NBA coating from interface to central zone, whereas multi-oriented dendrite and fine equiaxed dendrite growth by addition of n-CeO 2. The microhardness and wear resistance of coatings are greatly improved by CeO 2 powder addition, and compared to the addition of 1.0% and 3.0%, 1.5% n-CeO 2/NBA is the best. Hardness and wear resistance of the coating improves with decreasing CeO 2 size from micron to nano.

  15. Design of vehicular multimedia AD player based on embedded Linux%基于嵌入式Linux的车载多媒体广告机设计

    Institute of Scientific and Technical Information of China (English)

    郑继亭; 王润民; 张楠

    2014-01-01

    Aiming at the limitation of traditional vehicular multimedia AD player, a design method of vehicular multimedia AD player based on embedded Linux and Qt/Embedded is proposed. S3C6410 is adopted as the central processor in the hardware and the software platform uses Embedded Linux operating system. Additionally, the interface is developed by Qt, which is a type of open source graphical user interface library. The system adopts MPlayer as its media player. After experimental veriifcation, the AD player has the characteristic of low cost, user-friendly, quick reaction, and has a signiifcant improvement in cross-platform and scalability.%针对传统车载多媒体广告机的局限性,提出了一种基于嵌入式Liunx与Qt/Embedded的车载多媒体广告机的设计方案。该方案采用以ARM处理器S3C6410为核心的硬件平台和以嵌入式Linux系统为核心的软件平台,并在此基础上采用开放源代码的图形界面库Qt开发广告机界面,同时利用开源播放软件MPlayer作为播放器。经实验验证,该多媒体广告机具有成本较低、界面友好、反应灵敏等特点,并在跨平台性、可扩展性等方面比传统方案有显著改善。

  16. Research on Modules Partion Based on QFD and AD%基于QFD和公理化设计的模块划分方法研究

    Institute of Scientific and Technical Information of China (English)

    钟诗胜; 吴惠霞; 王琳

    2013-01-01

    模块划分作为模块化设计的第一步,必须充分考虑顾客的需求和功能独立性.在现有研究的基础上,提出了基于质量功能配置(Quality Function Deployment,QFD)和公理化设计(Axiomatic Design,AD)的模块划分方法.运用QFD和AD理论,保证产品的功能分解时满足顾客需求和功能的独立性.在功能模块的聚合方式上,对原有的模糊聚类方法进行改进.在聚类计算之前,先进行模块分组,后在组内进行聚类.减小了模块聚类的计算量,并有利于模块化设计的优化.%As the first step of modular design,modules partition must consider the customers needs and function indpendence. On the basis of previous researches,a modules partion method based on the Quality Function Deployment (QFD)and Axiomatic Design (AD )theory is proposed.QFD and AD theory can ensure the customers' needs and function independence. And improve the original function modules cluster method with group cluster.Before modules cluster,dividing them into groups ,which can reduce the computation time and benefit for modular design optimization.

  17. Data acquisition system of 16-channel EEG based on ATSAM3X8E ARM Cortex-M3 32-bit microcontroller and ADS1299

    Science.gov (United States)

    Toresano, L. O. H. Z.; Wijaya, S. K.; Prawito, Sudarmaji, A.; Badri, C.

    2017-07-01

    The prototype of the EEG (electroencephalogram) instrumentation systems has been developed based on 32-bit microcontrollers of Cortex-M3 ATSAM3X8E and Analog Front-End (AFE) ADS1299 (Texas Instruments, USA), and also consists of 16-channel dry-electrodes in the form of EEG head-caps. The ADS1299-AFE has been designed in a double-layer format PCB (Print Circuit Board) with daisy-chain configuration. The communication protocol of the prototype was based on SPI (Serial Peripheral Interface) and tested using USB SPI-Logic Analyzer Hantek4032L (Qingdao Hantek Electronic, China). The acquired data of the 16-channel from this prototype has been successfully transferred to a PC (Personal Computer) with accuracy greater than 91 %. The data acquisition system has been visualized with time-domain format in the multi-graph plotter, the frequency-domain based on FFT (Fast Fourier Transform) calculation, and also brain-mapping display of 16-channel. The GUI (Graphical User Interface) has been developed based on OpenBCI (Brain Computer Interface) using Java Processing and also can be stored of data in the *.txt format. Instrumentation systems have been tested in the frequency range of 1-50 Hz using MiniSim 330 EEG Simulator (NETECH, USA). The validation process has been done with different frequency of 0.1 Hz, 2 Hz, 5 Hz, and 50 Hz, and difference voltage amplitudes of 10 µV, 30 µV, 50 µV, 100 µV, 500 µV, 1 mV, 2 mV and 2.5 mV. However, the acquisition system was not optimal at a frequency of 0.1 Hz and for amplitude potentials of over 1 mV had differences of the order 10 µV.

  18. Probing crunching AdS cosmologies

    Science.gov (United States)

    Kumar, S. Prem; Vaganov, Vladislav

    2016-02-01

    Holographic gravity duals of deformations of CFTs formulated on de Sitter spacetime contain FRW geometries behind a horizon, with cosmological big crunch singularities. Using a specific analytically tractable solution within a particular single scalar truncation of {N}=8 supergravity on AdS4, we first probe such crunching cosmologies with spacelike radial geodesics that compute spatially antipodal correlators of large dimension boundary operators. At late times, the geodesics lie on the FRW slice of maximal expansion behind the horizon. The late time two-point functions factorise, and when transformed to the Einstein static universe, they exhibit a temporal non-analyticity determined by the maximal value of the scale factor ã max. Radial geodesics connecting antipodal points necessarily have de Sitter energy Ɛ ≲ ã max, while geodesics with Ɛ > ã max terminate at the crunch, the two categories of geodesics being separated by the maximal expansion slice. The spacelike crunch singularity is curved "outward" in the Penrose diagram for the deformed AdS backgrounds, and thus geodesic limits of the antipodal correlators do not directly probe the crunch. Beyond the geodesic limit, we point out that the scalar wave equation, analytically continued into the FRW patch, has a potential which is singular at the crunch along with complex WKB turning points in the vicinity of the FRW crunch. We then argue that the frequency space Green's function has a branch point determined by ã max which corresponds to the lowest quasinormal frequency.

  19. On the Added Value of Quad-Pol Data in a Multi-Temporal Crop Classification Framework Based on RADARSAT-2 Imagery

    Directory of Open Access Journals (Sweden)

    Arantzazu Larrañaga

    2016-04-01

    Full Text Available Polarimetric SAR images are a rich data source for crop mapping. However, quad-pol sensors have some limitations due to their complexity, increased data rate, and reduced coverage and revisit time. The main objective of this study was to evaluate the added value of quad-pol data in a multi-temporal crop classification framework based on SAR imagery. With this aim, three RADARSAT-2 scenes were acquired between May and June 2010. Once we analyzed the separability and the descriptive analysis of the features, an object-based supervised classification was performed using the Random Forests classification algorithm. Classification results obtained with dual-pol (VV-VH data as input were compared to those using quad-pol data in different polarization bases (linear H-V, circular, and linear 45°, and also to configurations where several polarimetric features (Pauli and Cloude–Pottier decomposition features and co-pol coherence and phase difference were added. Dual-pol data obtained satisfactory results, equal to those obtained with quad-pol data (in H-V basis in terms of overall accuracy (0.79 and Kappa values (0.69. Quad-pol data in circular and linear 45° bases resulted in lower accuracies. The inclusion of polarimetric features, particularly co-pol coherence and phase difference, resulted in enhanced classification accuracies with an overall accuracy of 0.86 and Kappa of 0.79 in the best case, when all the polarimetric features were added. Improvements were also observed in the identification of some particular crops, but major crops like cereals, rapeseed, and sunflower already achieved a satisfactory accuracy with the VV-VH dual-pol configuration and obtained only minor improvements. Therefore, it can be concluded that C-band VV-VH dual-pol data is almost ready to be used operationally for crop mapping as long as at least three acquisitions in dates reflecting key growth stages representing typical phenology differences of the present crops are

  20. SUSY properties of warped AdS3

    Science.gov (United States)

    Jeong, Jaehoon; Colgáin, Eoin Ó.; Yoshida, Kentaroh

    2014-06-01

    We examine supersymmetric properties of null-warped AdS3, or alternatively Schrödinger geometries, dual to putative warped CFTs in two dimensions. We classify super Schrödinger subalgebras of the superalgebra psu(1, 1|2) ⊕ psu(1, 1|2), corresponding to the superconformal algebra of the AdS3 × S3 geometry. We comment on geometric realisations and provide a string theory description with enhanced supersymmetry in terms of intersecting D3-branes. For type IIB supergravity solutions based on T 1,1, we consider the relationship between five-dimensional Schrödinger solutions and their three-dimensional null-warped counterparts, corresponding to R symmetry twists. Finally, we study a family of null-warped AdS3 solutions in a setting where there is an ambiguity over the R symmetry and confirm that, for examples admitting a Kaluza-Klein (KK) reduction to three dimensions, the minimisation of a real superpotential of the three-dimensional gauged supergravity captures the central charge and R symmetry.

  1. Valutazione della capacità di rientro alla base di un elicottero in presenza di danno balistico ad un albero di trasmissione della linea rotore di coda

    National Research Council Canada - National Science Library

    L Giudici; A Manes; M Giglio

    2010-01-01

      Nella progettazione di un elicottero militare, destinato ad operare a bassa quota e in ambiente ostile, il danneggiamento di componenti critici, conseguente ad impatto balistico, riveste un ruolo...

  2. Teberda valley runoff variability (AD 1797-2003) based on tree-ring reconstruction (Northern Caucasus, Russia)

    Science.gov (United States)

    Matskovskiy, V. V.; Dolgova, E. A.; Solomina, O. N.

    2009-04-01

    In this paper we provide a new tree-ring based runoff reconstruction for Teberda river for 1797-2003. Teberda river is a tributary of Kuban' (Azov Sea basin), 60 km long with the watershed surface equal to 1080 km2. 60% of runoff occurs in summer, 17% - in the fall, 5% - in winter, 18% - in spring. 55,8% of runoff (at Teberda hydrological station) is provided by snow and ice melt (Lurye 2000). No statistically significant trend is identified in the Teberda runoff records in 1930-2000 despite of some important climatic and environmental changes occurred in this period in the Northern Caucasus, namely a general warming in winter, increase in solid precipitation and recession of glaciers. Tree-ring properties were successfully used previously to reconstruct streamflow (Stockton and Jacoby, 1976, Woodhouse et al., 2006) in the regions where drought influence both tree growth and river runoff regime. In the Northern Caucasus, even at the upper tree limit pine and spruce growth is largely limited by the availability of water (Dologva et al., 2007). The correlation between Pinus silvestris ring width and June-July Teberda river runoff is 0.4, while it increases up to 0.69 for 11-years running mean. We used linear regression of instrumental records of Teberda runoff (1927-2000) and first principal component of the pine ring width chronologies from the same valley to reconstruct the June-July runoff for the period 1797-2003. Our chronology is two centuries longer, but its reliable portion (EPS > 0.8) begin in the late 18th century. We used cross-validation to verify the reconstruction, so the correlation coefficient is 0.72 and mean difference is 23.13 (52% of interquartile range) between reconstruction and instrumental record for the verification period. The reconstruction reproduces well the general trends in runoff variability, but slightly underestimates the amplitude of the runoff positive anomalies in 1940s. The positive peaks of reconstructed runoff are centered

  3. Effect of aluminum addition on electrical properties, dielectric characteristics, and its stability of (Pr, Co, Cr, Y)-added zinc oxide-based varistors

    Indian Academy of Sciences (India)

    Choon-W Nahm

    2010-06-01

    The electrical properties, dielectric characteristics, and its stability against d.c. accelerated aging stress of (Pr, Co, Cr, Y)-added zinc oxide-based varistors were investigated for different aluminum concentrations under a sintering temperature of 1280°C. As the aluminum concentration increased, the average grain size () increased in the range of 4.3–5.5 m and the sintered density increased in the range of 5.63–5.67 g/cm3. As the aluminum concentration increased, the breakdown field decreased in the range of 6327–710 V/cm and the maximum nonlinear coefficient (46.9) was obtained for 0.005 mol% in aluminum concentration, further additions impaired the nonlinear properties. As the aluminum concentration increased, the apparent dielectric constant increased in the range of 500.5–1327.4 and dissipation factor increased in the range of 0.00493–0.0724. The varistor added with 0.001 mol% Al exhibited the highest stability for – characteristics in which % 1\\ mA is +1.4% and % is –5.7%, under stress state of 0.95 1\\ mA/150° C/24 h.

  4. 基于ADS高效率微波功率放大器设计%Design of high effective microwave power amplifier based on ADS software

    Institute of Scientific and Technical Information of China (English)

    胡小军

    2012-01-01

    基于ADS软件,选取合适的静态直流工作点,采用负载牵引法得到LDMOS晶体管BLF7G22L130的输出和输入阻抗特性,并通过设计和优化得到最佳的共轭匹配网络,设计出高效率功率放大器。ADS设计仿真表明该功率放大器在中心频率2 160 MHz处的效率达到70%,稳定性好、增益平坦度小等优点。%Based on ADS software,the high effective and power amplifier can be designed after learning the output and input impedance characteristic of the LDMOS transistor BLF7G22L130 by Load-pulling method under an appropriate static DC point and realizing the best conjugate match network through design and optimizing.ADS simulation indicates that the effectiveness of this kind of amplifier reaches 70% at the center frequency of 2 160 MHz,with the advantages of high stability and low gain flatness.

  5. Biorefining of by-product streams from sunflower-based biodiesel production plants for integrated synthesis of microbial oil and value-added co-products.

    Science.gov (United States)

    Leiva-Candia, D E; Tsakona, S; Kopsahelis, N; García, I L; Papanikolaou, S; Dorado, M P; Koutinas, A A

    2015-08-01

    This study focuses on the valorisation of crude glycerol and sunflower meal (SFM) from conventional biodiesel production plants for the separation of value-added co-products (antioxidant-rich extracts and protein isolate) and for enhancing biodiesel production through microbial oil synthesis. Microbial oil production was evaluated using three oleaginous yeast strains (Rhodosporidium toruloides, Lipomyces starkeyi and Cryptococcus curvatus) cultivated on crude glycerol and nutrient-rich hydrolysates derived from either whole SFM or SFM fractions that remained after separation of value-added co-products. Fed-batch bioreactor cultures with R. toruloides led to the production of 37.4gL(-1) of total dry weight with a microbial oil content of 51.3% (ww(-1)) when a biorefinery concept based on SFM fractionation was employed. The estimated biodiesel properties conformed with the limits set by the EN 14214 and ASTM D 6751 standards. The estimated cold filter plugging point (7.3-8.6°C) of the lipids produced by R. toruloides is closer to that of biodiesel derived from palm oil.

  6. Design of 5 .8GHz Circular Microstrip Rectenna Based on ADS%基于 ADS 的5.8GHz 圆形微带整流天线仿真设计

    Institute of Scientific and Technical Information of China (English)

    耿凯峰; 刘丽; 漆世锴

    2016-01-01

    Rectenna is one of the critical components of wireless power transmission(WPT ) .Common rectangle patch microstrip antenna have its shortages which include oversize area ,high-cost ,difficult integration and so on .According to the design theory of circular microstrip antenna and a source of feed cavity model theory ,a novel 5 .8GHz circular microstrip re-ctenna is designed .Optimizing the designed circular microstrip rectenna using ADS2008 software ,which makes this receiving antenna area of circular microstrip rectenna nearly 4 times smaller than the same kind rectangle patch microstrip antenna .It not only greatly reduces the production cost ,but also is easy to be integrated and conformal ,more suitable to make up anten-na array .Experimental results show that power transmission efficiency of this rectenna system is above 70% ,which indirect-ly demonstrates the simulation and optimization of this microstrip rectenna availability using ADS2008 software .%整流天线是无线能量传输的关键部件之一。常用的矩形微带天线存在面积大、成本高、不易集成等不足。根据圆形微带天线设计理论和有馈源的空腔模型理论,设计了一种工作在5.8GHz 的新型圆形微带整流天线。经过ADS2008软件仿真优化使得该圆形微带整流天线的接收天线面积比同类矩形微带天线将近小4倍左右,这不仅大大降低了生产成本,而且易集成和共形,更适合组成天线阵。实验结果表明,该整流天线系统的输能效率可达到70%以上,间接说明了利用 ADS2008仿真优化该微带整流天线的可行性。

  7. Design of single-chip broad band phase bias measure system based on AD8302%基于AD8302的单片宽频带相位差测量系统的设计

    Institute of Scientific and Technical Information of China (English)

    沙占友; 刘阿芳; 王科

    2006-01-01

    在移动通信系统中,经常需要精确测量相位差.详细阐述了利用AD8302构成的宽频带相位差及频率测量系统.该系统可精确测量从低频到射频范围内0°~360°的相位差(测量误差小于0.5°),-60dBm~0dBm范围内的功率电平以及10MHz以下的频率.

  8. The political attack ad

    Directory of Open Access Journals (Sweden)

    Palma Peña-Jiménez, Ph.D.

    2011-01-01

    Full Text Available During election campaigns the political spot has a clear objective: to win votes. This message is communicated to the electorate through television and Internet, and usually presents a negative approach, which includes a direct critical message against the opponent, rather than an exposition of proposals. This article is focused on the analysis of the campaign attack video ad purposely created to encourage the disapproval of the political opponent among voters. These ads focus on discrediting the opponent, many times, through the transmission of ad hominem messages, instead of disseminating the potential of the political party and the virtues and manifesto of its candidate. The article reviews the development of the attack ad since its first appearance, which in Spain dates back to 1996, when the famous Doberman ad was broadcast, and examines the most memorable campaign attack ads.

  9. Simulation and Analysis of Mobile Ad hoc Network Routing Protocol Based on NS%移动Ad hoc网络路由协议的ns模拟分析

    Institute of Scientific and Technical Information of China (English)

    刘星宇

    2011-01-01

    Ad hoc网络是一种自组网,移动节点必须具备路由功能,那么路由协议选择至关重要.文章介绍了DSDV、DSR和AODV几种典型的路由协议.然后采用NS模拟的方法,得到了吞吐量、丢包率和端到端的延时性能分析图.通过对模拟结果的分析比较,给出这几种路由协议的优缺点及未来路由协议的发展方向.%Ad hoc network is a MANET, mobile nodes must have the routing function, so the routing protocol selection is critical. This paper introduces the DSDV, DSR and AODV routing protocols. We obtain the throughput, packet loss and delay performance analysis chart by NS simulation. It gives the advantages and disadvantages of these types of routing protocols and the future direction of development of routing protocols.

  10. A novel D2-A-D1-A-D2-type donor-acceptor conjugated small molecule based on a benzo[1,2-b:4,5-b‧]dithiophene core for solution processed organic photovoltaic cells

    Science.gov (United States)

    Yu, Junting; Zhu, Weiguo; Tan, Hua; Peng, Qing

    2017-01-01

    A novel D2-A-D1-A-D2-type donor-acceptor conjugated small molecule (DTPA-Q-BDT-Q-DTPA) with a benzo[1,2-b:4,5-b‧]dithiophene (BDT) core and two D2-A arms has been synthesized and employed as electron donor for organic solar cells. Solution-processed organic photovoltaic (OPV) devices were fabricated with a configuration of ITO/PEDOT:PSS/DTPA-Q-BDT-Q-DTPA:[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM)/LiF/Al. A power conversion efficiency (PCE) of 1.22% with an open-circuit voltage (VOC) of 0.64 V, a short-circuit current (JSC) of 6.10 mA cm-2, and a fill factor (FF) of 31.0% was achieved. The PCE is 2.9 times higher than that in the other devices using D2-A-type small molecule TPA-Q-TPA as donor.

  11. 基于STM32和AD5933的多通道阻抗测量仪的设计与实现%Design of Multichannel Impedance Meter Based on AD5933 and STM32

    Institute of Scientific and Technical Information of China (English)

    刘亮; 朱璐闻; 艾颖梅; 伍群芳

    2014-01-01

    针对目前传统使用的阻抗测量仪通道少、精度低、操作复杂等诸多缺点,研制了一款测量阻抗范围0~10MΩ、支持USB总线的全自动多通道阻抗测量仪;系统采用STM32F103C8T6处理器为控制核心,高精度阻抗转换芯片AD5933为测量核心,通过上位机设置AD5933配置参数即可完成多通道的单频、多频自动化测量,阻抗数据经USB总线传输至上位机存储及图形方式显示;结果表明该测量仪电路集成度高,操作简单,而且测量相对误差小于1%,性能稳定可靠.

  12. Signal processing system of dual-frequency laser interferometer with two longitudinal modes based on AD8302%基于AD8302的双纵模双频激光干涉仪信号处理系统

    Institute of Scientific and Technical Information of China (English)

    韦进强; 张涛; 何子牛; 吴振林

    2009-01-01

    为了解决双纵模双频激光干涉仪原有信号处理电路两路信号易直流漂移、不正交对干涉仪系统测量精度和速度的限制及调整光路观察信号不方便等问题,利用AD8302的良好高频处理特性,设计了一种新的基于AD8302的双纵模双频激光干涉仪信号处理系统,给出了方案的总体框图和信号处理流程图,详细地分析了其工作原理以及提高相位测量精度方法.由于器件相位测量的高分辨率,该系统也可用于高分辨率双纵模双频激光轮廓仪的信号处理.

  13. Study on Remote Data Acquisition & Preprocessing Based on Ad hoc and Lab VIEW%基于Ad hoc和Lab VIEW的远程数据采集及预处理的研究

    Institute of Scientific and Technical Information of China (English)

    王建芳; 李伟华

    2008-01-01

    针对基于Ad hoe无线网络环境下的远程自动测试智能信息处理系统的多扰动、紧耦合的特点,提出了在Ad hoc网络环境下基于Lab VIEW 提取多传感器特征参数并进行预处理的技术,实现了实时动态的监测、数据的存储、远程通信和回放显示;采用Lab VIEW和网络传输技术,实现了远程测试系统的数据采集和预处理平台的开发;实测结果分析表明,经过数据采集及预处理后,降低了冗余数据量,提高了网络资源利用率,减少了系统开发成本.

  14. Probing crunching AdS cosmologies

    CERN Document Server

    Kumar, S Prem

    2015-01-01

    Holographic gravity duals of deformations of CFTs formulated on de Sitter spacetime contain FRW geometries behind a horizon, with cosmological big crunch singularities. Using a specific analytically tractable solution within a particular single scalar truncation of N=8 supergravity on AdS_4, we first probe such crunching cosmologies with spacelike radial geodesics that compute spatially antipodal correlators of large dimension boundary operators. At late times, the geodesics lie on the FRW slice of maximal expansion behind the horizon. The late time two-point functions factorise, and when transformed to the Einstein static universe, they exhibit a temporal non-analyticity determined by the maximal value of the scale factor a_{max} . Radial geodesics connecting antipodal points necessarily have de Sitter energy E \\leq a_{max}, while geodesics with E > a_{max} terminate at the crunch, the two categories of geodesics being separated by the maximal expansion slice. The spacelike crunch singularity is curved "outw...

  15. Holography of AdS vacuum bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Barbon, J.L.F. [Instituto de Fisica Teorica IFT UAM/CSIC, Cantoblanco, Madrid 28049 (Spain); Rabinovici, E. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2011-07-15

    We consider the fate of AdS vacua connected by tunneling events. A precise holographic dual of thin-walled Coleman-de Luccia bounces is proposed in terms of Fubini instantons in an unstable CFT. This proposal is backed by several qualitative and quantitative checks, including the precise calculation of the instanton action appearing in evaluating the decay rate. Big crunches manifest themselves as time dependent processes which reach the boundary of field space in a finite time. The infinite energy difference involved is identified on the boundary and highlights the ill-defined nature of the bulk setup. We propose a qualitative scenario in which the crunch is resolved by stabilizing the CFT, so that all attempts at crunching always end up shielded from the boundary by the formation of black hole horizons. In all these well defined bulk processes the configurations have the same asymptotics and are finite energy excitations.

  16. Twistor methods for AdS$_5$

    CERN Document Server

    Adamo, Tim; Williams, Jack

    2016-01-01

    We consider the application of twistor theory to five-dimensional anti-de Sitter space. The twistor space of AdS$_5$ is the same as the ambitwistor space of the four-dimensional conformal boundary; the geometry of this correspondence is reviewed for both the bulk and boundary. A Penrose transform allows us to describe free bulk fields, with or without mass, in terms of data on twistor space. Explicit representatives for the bulk-to-boundary propagators of scalars and spinors are constructed, along with twistor action functionals for the free theories. Evaluating these twistor actions on bulk-to-boundary propagators is shown to produce the correct two-point functions.

  17. AdS2 holographic dictionary

    Science.gov (United States)

    Cvetič, Mirjam; Papadimitriou, Ioannis

    2016-12-01

    We construct the holographic dictionary for both running and constant dilaton solutions of the two dimensional Einstein-Maxwell-Dilaton theory that is obtained by a circle reduction from Einstein-Hilbert gravity with negative cosmological constant in three dimensions. This specific model ensures that the dual theory has a well defined ultraviolet completion in terms of a two dimensional conformal field theory, but our results apply qualitatively to a wider class of two dimensional dilaton gravity theories. For each type of solutions we perform holographic renormalization, compute the exact renormalized one-point functions in the presence of arbitrary sources, and derive the asymptotic symmetries and the corresponding conserved charges. In both cases we find that the scalar operator dual to the dilaton plays a crucial role in the description of the dynamics. Its source gives rise to a matter conformal anomaly for the running dilaton solutions, while its expectation value is the only non trivial observable for constant dilaton solutions. The role of this operator has been largely overlooked in the literature. We further show that the only non trivial conserved charges for running dilaton solutions are the mass and the electric charge, while for constant dilaton solutions only the electric charge is non zero. However, by uplifting the solutions to three dimensions we show that constant dilaton solutions can support non trivial extended symmetry algebras, including the one found by Compère, Song and Strominger [1], in agreement with the results of Castro and Song [2]. Finally, we demonstrate that any solution of this specific dilaton gravity model can be uplifted to a family of asymptotically AdS2 × S 2 or conformally AdS2 × S 2 solutions of the STU model in four dimensions, including non extremal black holes. The four dimensional solutions obtained by uplifting the running dilaton solutions coincide with the so called `subtracted geometries', while those obtained

  18. An evidence-based unified definition of lifelong and acquired premature ejaculation : report of the second international society for sexual medicine ad hoc committee for the definition of premature ejaculation

    National Research Council Canada - National Science Library

    Serefoglu, Ege Can; McMahon, Chris G; Waldinger, Marcel D; Althof, Stanley E; Shindel, Alan; Adaikan, Ganesh; Becher, Edgardo F; Dean, John; Giuliano, Francois; Hellstrom, Wayne Jg; Giraldi, Annamaria; Glina, Sidney; Incrocci, Luca; Jannini, Emmanuele; McCabe, Marita; Parish, Sharon; Rowland, David; Segraves, R Taylor; Sharlip, Ira; Torres, Luiz Otavio

    2014-01-01

    INTRODUCTION: The International Society for Sexual Medicine (ISSM) Ad Hoc Committee for the Definition of Premature Ejaculation developed the first evidence-based definition for lifelong premature ejaculation (PE...

  19. Agent Virus of Cooperation (Avicoop: an Intelligent Model of Cooperation and Collaboration Based on the MAS for Data Exchange in Ad hoc Network

    Directory of Open Access Journals (Sweden)

    Claude Tangha

    2012-09-01

    Full Text Available We propose in this paper a response to the problem of cooperation and collaboration between nodes in a mobile ad hoc network (MANET for intelligent data relays from one source to a destination. In their operation, each routing protocol relies on the support of each node for end-to-end messages routing by completely ignoring the autonomous nature of the node that is to be free to accept, reject, relay or otherwise simply manipulate the protocols principle. This random and unpredictable behavior of the node impacts on the routing effectiveness in the global network. Our approach is based on multi-agent systems (MAS and game theory, especially the iterated version of the Prisoner's Dilemma. The proposed model is validated by a prototype.

  20. Performance Improvement of GaN Based Schottky Barrier Ultraviolet Photodetector by Adding a Thin AlGaN Window Layer

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mei; ZHAO De-Gang

    2007-01-01

    We propose a new structure of GaN based Schottky barrier ultraviolet photodetector, in which a thin n-type AlGaN window layer is added on the conventional n--GaN/n+-GaN device structure. The performance of the Schottky barrier ultraviolet photodetector is found to be improved by the new structure. The simulation result shows that the new structure can reduce the negative effect of surface states on the performance of Schottky barrier GaN photodetectors, improving the quantum efficiency and decreasing the dark current. The investigations suggest that the new photodetector can exhibit a better responsivity by choosing a suitably high carrier concentration and thin thickness for the AlGaN window layer.

  1. A Novel Approach Towards Cost Effective Region-Based Group Key Agreement Protocol for Peer - to - Peer Information Sharing in Mobile Ad Hoc Networks

    CERN Document Server

    Kumar, K; Sumathy, V

    2010-01-01

    Peer-to-peer systems have gained a lot of attention as information sharing systems for the widespread exchange of resources and voluminous information that is easily accessible among thousands of users. However, current peer-to-peer information sharing systems work mostly on wired networks. With the growing number of communication-equipped mobile devices that can self-organize into infrastructure-less communication platform, namely mobile ad hoc networks (MANETs), peer-to-peer information sharing over MANETs becomes a promising research area. In this paper, we propose a Region-Based structure that enables efficient and secure peer-to-peer information sharing over MANETs. The implementation shows that the proposed scheme is Secure, scalable, efficient, and adaptive to node mobility and provides Reliable information sharing.

  2. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers.

    Science.gov (United States)

    Alvarez, María Dolores; Cuesta, Francisco Javier; Herranz, Beatriz; Canet, Wenceslao

    2017-01-02

    An attempt was made to analyze the elastic modulus (G0) of chickpea flour (CF)-based muffin batters made with CF alone and with added biopolymers (whey protein (WP), xanthan gum (XG), inulin (INL), and their blends) in order to evaluate their suitability to be a wheat flour (WF) substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 ◦C to 90 ◦C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n), frequency factor (k0), and activation energy (Ea)) using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G0 value. The change of the derivative of G0 with respect to time (dG0/dt) versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol-1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins.

  3. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers

    Directory of Open Access Journals (Sweden)

    María Dolores Alvarez

    2017-01-01

    Full Text Available An attempt was made to analyze the elastic modulus (G0 of chickpea flour (CF-based muffin batters made with CF alone and with added biopolymers (whey protein (WP, xanthan gum (XG, inulin (INL, and their blends in order to evaluate their suitability to be a wheat flour (WF substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 ◦C to 90 ◦C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n, frequency factor (k0, and activation energy (Ea using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G0 value. The change of the derivative of G0 with respect to time (dG0/dt versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol−1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins.

  4. A cross-layer design and ant-colony optimization based load-balancing routing protocol for ad-hoc networks

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiangquan; GUO Wei; GE Lijia; LIU Renting

    2007-01-01

    In order to periodically reassess the status of the alternate path route (APR) set and to improve the efficiency of alternate path construction existing in most current alternate path routing protocols,we present a cross-layer design and ant-colony optimization based load-balancing routing protocol for ad-hoc networks (CALRA) in this paper.In CALRA,the APR set maintained in nodes is aged and reassessed by the inherent mechanism of pheromone evaporation of ant-colony optimization algorithm,and load balance of network is achieved by ant-colony optimization combining with cross-layer synthetic optimization.The efficiency of APR set construction is improved by bidirectional and hop-by-hop routing update during routing discovery and routing maintenance process.Moreover,ants in CALRA deposit simulated pheromones as a function of multiple parameters corresponding to the information collected by each layer of each node visited,such as the distance from their source node,the congestion degree of the visited nodes,the current pheromones the nodes possess,the velocity of the nodes,and so on,and provide the information to the visiting nodes to update their pheromone tables by endowing the different parameters corresponding to different information and different weight values,which provides a new method to improve the congestion problem,the shortcut problem,the convergence rate and the heavy overheads commonly existed in existing ant-based routing protocols for ad-hoc networks.The performance of the algorithm is measured by the packet delivery rate,good-put ratio (routing overhead),and end-to-end delay.Simulation results show that CALRA performs well in decreasing the route overheads,balancing traffic load,as well as increasing the packet delivery rate,etc.

  5. Strategy of Advertising Information Value-added Based on Creativity of Media%基于媒介创意的广告信息增值策略

    Institute of Scientific and Technical Information of China (English)

    杨暖暖

    2012-01-01

    Based on media, the necessity of advertising information value-added research was made clear, combined with the environment of media and communication. The form and value of media, viral advertising, oral spreading and micro film were analyzed. The strategies of advertising information value-added based on creativity of media were proposed, including hyperlink, sharing, interaction and integration. The commonness of the strategies was analyzed. All of these presented a series of new characters: interactive experience, open and independent, flexible and entertainment orientation.%以媒介为切入点,结合现代媒体环境与信息传播环境,明确了广告信息价值与信息增值策略研究的必要性。通过对媒介形态、媒介价值以及病毒式广告、口碑传播、微电影等具体广告形式的分析,重点提出了以媒介创意为核心的广告信息增值策略,包括超链接、分享式、交互式、融合式策略等主要形式,并在此基础上进行了广告信息增值策略的共性分析,总结提出了互动体验、开放自主、灵活多变,以及娱乐话题性等主要特征。

  6. Skil problemerne ad

    DEFF Research Database (Denmark)

    Kaspersen, Peter

    2007-01-01

    På grundlag af evalueringer og forskning i gymnasiereformen 2005 foreslås det at skille problemerne ad i forskellige niveauer. Herved kan der arbejdes med niveaudelte løsninger.......På grundlag af evalueringer og forskning i gymnasiereformen 2005 foreslås det at skille problemerne ad i forskellige niveauer. Herved kan der arbejdes med niveaudelte løsninger....

  7. Design and Improvement of Phase Bias Measure System Based on AD8302%基于AD8302的相位差测量系统的改进和设计

    Institute of Scientific and Technical Information of China (English)

    刘文豹; 彭浩

    2014-01-01

    介绍了AD8302幅相检测芯片的功能和应用局限性,提出一种电路结构,引入90°电桥和功分器电路,使该芯片的检测相位差的范围从0°~180°扩大到0°~360°。并软件设计了PCB版图和腔体,并进行了加工和测试。证明该电路结构可以精确地测试两路信号的相位差,测试范围为0°~360°,工作范围为500~2700MHz。本文网络版地址:http://www.eepw. com.cn/article/203222.htm

  8. 基于AD8302的牵引电动机主极裂纹检测仪的研制%Development of Main Electrode Crack Detector for Traction Motor Based on AD8302

    Institute of Scientific and Technical Information of China (English)

    余为清; 刘举平

    2006-01-01

    为实现电力机车牵引电动机主极裂纹的无损检测,利用IF/RF芯片AD8302作为涡流检测中的幅相检测核心器件,配合SPCE061A单片机研发了一种便携式涡流裂纹检测仪.仪器具有体积小,灵敏度高,操作智能化等诸多优点.试验表明:该测试系统能够对电力机车主极裂纹进行准确有效的检测.

  9. Design of ECG Monitoring of the Amplified Signal Based on AD620%基于AD620的心电监测放大信号的设计

    Institute of Scientific and Technical Information of China (English)

    常星

    2016-01-01

    为了方便人们实时了解心律变化,得到较为准确的心电信号特征。提出了一种心电放大信号电路的设计,该设计采用低功耗、低成本、高精度仪表放大器AD620将心电信号(ECG)进行数据采集放大后,然后再经过低噪声、高精度、高度运算放大器OP07组成的滤波电路及主放大电路对前级放大的心电信号进行电路处理从而得到较为精确的心电信号。通过硬件测试系统达到了能够检测心电信好的目的。设计具有一定的实际应用价值。%In order to facilitate the people to understand the real-time heart rate variability to obtain more a-ccurate ECG feature.Proposed a ECG signal amplifying circuit design that uses low-power,low cost,high a-ccuracy instrumentation amplifier AD620 the ECG(ECG)be enlarged after data col ection,and then through t-he low pass noise,high accuracy,the height of the operational amplifier OP07 filter circuit composed of the m-ain amplifier and preamp on the ECG signal processing circuit to obtain a more accurate ECG.Hardware test system capable of detecting heart Telecom reached a good purpose.Design has some practical value.

  10. 基于AD7745的数字式油品检测传感器设计%Design of digital sensor for oil quality detection based on AD7745

    Institute of Scientific and Technical Information of China (English)

    刘海仓; 滕召胜; 刘静波; 熊海涛; 罗彬

    2011-01-01

    植物油掺伪后难以检测,根据不同油品具有不同介电常数的特性,设计了通过电容值进行检测的数字式油品传感器,建立了传感器等效电路,分析了传感器结构对电容检测的影响.传感器为插杆状结构,平板电容极板为敏感元件,检测时不同油品介质引起的电容量变化经AD7745转换成相应的数字量通过I2C串行总线口输出.实验结果表明:数字式油品传感器能够对掺伪3%以上的植物油进行快速有效鉴别,重复性优于0.2%.%It's difficult to detect whether the edible vegetable oil is adulteration. According to the characteristics that one kind of oil's permittivity is different from others,a capacitive sensor is designed for oil quality detection. The equivalent circuit of the sensor is established to analyze the impact of sensor structure on capacitance detection. The sensor is rod-shaped, and the probe of plate capacitor is sensing unit. The AD7745 chip is used to detect the capacitance change due to different oil quality acting as medium. The detecting result of the sensor is displayed digitally,and is output through the I2C serial bus port. Experiment shows that the sensor can distinguish quickly whether the oil contain adulteration or not to above 3 % edible vegetable oil,and its repeatability is prior to 0.2%.

  11. Random Graph Generation Based p-Method and Box Method for the Evaluation of Power-Aware Routing Protocols of Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    Saleh H.A. Sharaeh

    2008-01-01

    Full Text Available The objective of this paper is to investigate the best solution such that on which decision should be made to forward a wireless packet. The decision should be made in such a way to keep the node alive by choosing an alternate path, through those nodes that have more power reserve. Minimizing the consumption of the reserve power will results in an increase in the number of hops the packet must travel. A hybrid solution can be utilized which is a combination of power-aware and minimizing the number of hops to be traveled. Recent research suggests that it should select the node with high power reserve than based on the shortest path. A question arises which is more critical for ad hoc networks the power-aware solution or the shortest path based on the number of hops. This research will investigate these solutions aiming on minimizing power consumption for wireless packets networks and the number of hops to be traveled. Through rigorous empirical analysis based on the p-method and box-space method, we were able to derive critical global properties with respect to end-to-end minimum power consumption routes. Finally, a simulation results are presented to verify the performance of the proposed algorithms.

  12. Ocean-Based Alkalinity Enhancement: Mitigation Potential, Side Effects and the Fate of Added Alkalinity Assessed in an Earth System Model

    Science.gov (United States)

    Gonzalez, M. F.; Ilyina, T.

    2014-12-01

    Artificial ocean alkalinization (AOA) has been proposed as a mean to mitigate climate change and ocean acidification. Whilst the mitigation potential of this geo-engineering technology may sound promising, it poses environmental risks. Within the Priority Program "Climate Engineering" of the German Science Foundation (DFG), we investigate the mitigation potential of AOA to reduce atmospheric CO2 and counteract the consequences of ocean acidification. We are particularly interested in the residence time of the added alkalinity at the ocean surface because it must stay in the upper ocean in order to increase the oceanic CO2 uptake. The mitigation potential, risks and the unintended consequences of this geo-engineering method are also exhaustively studied. These questions are tackled through the analysis of different alkalinity enhancement scenarios in the state-of-the-art Earth system model of the Max Planck Institute for Meteorology (MPI-ESM) in a configuration based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Model scenarios are designed so that AOA is performed to keep the atmospheric CO2 concentrations similar to values of the stabilization scenario RCP4.5, while fossil fuel CO2 emissions follow the pathway of the high-CO2 scenario RCP8.5. Alkalinity is added globally into the upper 12 meters of the ocean in different seasons and years. We found that on the time scale of relevance (i.e. from years to decades), season and location are key aspects to take into account in the implementation of AOA. This is because of inhomogeneous vertical mixing of added alkalinity due to the mixed layer depth which is established by the season. We also show that the rate of addition greatly determines impact and outcome of this geo-engineering method. Changes driven by the implementation of this method in the ocean biogeochemistry are also discussed. For instance, the associated changes in the carbon cycle, marine oxygen levels, saturation state of

  13. Probing crunching AdS cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Prem; Vaganov, Vladislav [Department of Physics, Swansea University,Singleton Park, Swansea SA2 8PP (United Kingdom)

    2016-02-03

    Holographic gravity duals of deformations of CFTs formulated on de Sitter spacetime contain FRW geometries behind a horizon, with cosmological big crunch singularities. Using a specific analytically tractable solution within a particular single scalar truncation of N=8 supergravity on AdS{sub 4}, we first probe such crunching cosmologies with spacelike radial geodesics that compute spatially antipodal correlators of large dimension boundary operators. At late times, the geodesics lie on the FRW slice of maximal expansion behind the horizon. The late time two-point functions factorise, and when transformed to the Einstein static universe, they exhibit a temporal non-analyticity determined by the maximal value of the scale factor ã{sub max}. Radial geodesics connecting antipodal points necessarily have de Sitter energy E≲ã{sub max}, while geodesics with E>ã{sub max} terminate at the crunch, the two categories of geodesics being separated by the maximal expansion slice. The spacelike crunch singularity is curved “outward” in the Penrose diagram for the deformed AdS backgrounds, and thus geodesic limits of the antipodal correlators do not directly probe the crunch. Beyond the geodesic limit, we point out that the scalar wave equation, analytically continued into the FRW patch, has a potential which is singular at the crunch along with complex WKB turning points in the vicinity of the FRW crunch. We then argue that the frequency space Green’s function has a branch point determined by ã{sub max} which corresponds to the lowest quasinormal frequency.

  14. OPNET based cognitive Ad Hoc networks modeling%基于OPNET的自组织认知无线网络建模

    Institute of Scientific and Technical Information of China (English)

    张晓艳; 扈罗全; 汪一鸣

    2013-01-01

    Appropriate cognitive nodes are designed and C-Ad Hoc networks architecture is established. By running appropriately modified AODV algorithm on the C-Ad Hoc networks, simulation results confirm the feasibility of the new designed networks.%设计了合适的认知节点,搭建了 C-Ad Hoc 网络架构。通过将AODV 算法进行适当修改,使其能够运行在C-Ad Hoc网络上,仿真结果验证了该网络模型的可行性。

  15. Cost-effectiveness of adding cetuximab to platinum-based chemotherapy for first-line treatment of recurrent or metastatic head and neck cancer.

    Directory of Open Access Journals (Sweden)

    Malek B Hannouf

    Full Text Available PURPOSE: To assess the cost effectiveness of adding cetuximab to platinum-based chemotherapy in first-line treatment of patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC from the perspective of the Canadian public healthcare system. METHODS: We developed a Markov state transition model to project the lifetime clinical and economic consequences of recurrent or metastatic HNSCC. Transition probabilities were derived from a phase III trial of cetuximab in patients with recurrent or metastatic HNSCC. Cost estimates were obtained from London Health Sciences Centre and the Ontario Case Costing Initiative, and expressed in 2011 CAD. A three year time horizon was used. Future costs and health benefits were discounted at 5%. RESULTS: In the base case, cetuximab plus platinum-based chemotherapy compared to platinum-based chemotherapy alone led to an increase of 0.093 QALY and an increase in cost of $36,000 per person, resulting in an incremental cost effectiveness ratio (ICER of $386,000 per QALY gained. The cost effectiveness ratio was most sensitive to the cost per mg of cetuximab and the absolute risk of progression among patients receiving cetuximab. CONCLUSION: The addition of cetuximab to standard platinum-based chemotherapy in first-line treatment of patients with recurrent or metastatic HNSCC has an ICER that exceeds $100,000 per QALY gained. Cetuximab can only be economically attractive in this patient population if the cost of cetuximab is substantially reduced or if future research can identify predictive markers to select patients most likely to benefit from the addition of cetuximab to chemotherapy.

  16. ad hoc networks

    Directory of Open Access Journals (Sweden)

    Blanca Alicia Correa

    2007-01-01

    Full Text Available Los métodos de agrupamiento permiten que las MANET (redes móviles ad hoc presenten un mejor desempeño en cuanto a la rapidez de conexión, el enrutamiento y el manejo de la topología. En este trabajo se presenta una revisión sobre las técnicas de agrupamiento para MANET. Se introducen algunos temas preliminares que forman la base para el desarrollo de los algoritmos de agrupamiento, tales como: la topología de la red, el enrutamiento, la teoría de grafos y los algoritmos de movilidad. Adicionalmente, se describen algunas de las técnicas de agrupamiento más conocidas como Lowest-ID heuristic, Highest degree heuristic, DMAC (distributed mobility-adaptive clustering, WCA (weighted clustering algorithm, entre otros. El propósito central es ilustrar los conceptos principales respecto a las técnicas de agrupamiento en MANET.

  17. Mobile ad hoc networking

    CERN Document Server

    John Wiley & Sons

    2004-01-01

    "Assimilating the most up-to-date information on research and development activities in this rapidly growing area, Mobile Ad Hoc Networking covers physical, data link, network, and transport layers, as well as application, security, simulation, and power management issues in sensor, local area, personal, and mobile ad hoc networks. Each of the book's sixteen chapters has been written by a top expert and discusses in-depth the most important topics in the field. Mobile Ad Hoc Networking is an excellent reference and guide for professionals seeking an in-depth examination of topics that also provides a comprehensive overview of the current state-of-the-art."--Jacket.

  18. 移动Ad Hoc网络中针对拥塞的RoQ DDoS攻击及其防御%Congestion-Based RoQ DDoS Attacking and Defense Scheme in Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    任伟; 刘腾红; 金海

    2006-01-01

    根据网络容量理论,移动Ad Hoc网络中存在针对拥塞的RoQ分布式拒绝服务攻击,其攻击模式包括脉冲攻击、循环攻击、自消耗攻击和泛洪攻击.防御机制包括检测和响应,检测信号包括RTS/CTS包频率、信号干涉频率以及包重传次数,响应机制依靠ECN标记和通知.NS2模拟结果显示,复杂拓扑结构将更容易受到攻击,攻击节点的分散将加大攻击效果.脉冲攻击产生明显的吞吐率和延迟抖动,当同速率攻击流增加到5个时,受害流吞吐率下降到77.42%,延迟增加110倍.

  19. 基于查找表的AD2S65芯片软件算法实现%AD2S65 Chip's Algorithms Implementation Based on Look_up_table

    Institute of Scientific and Technical Information of China (English)

    张海玲; 马雷; 柴波

    2010-01-01

    由于高性能DRC芯片的禁运,导致货源的紧缺和价格的上扬.为此提出了微处理器控制电路实现DRC芯片功能.介绍了DRC芯片AD2S65的功能特点及工作原理,提出了DRC芯片电路实现的方案--基于C8051F单片机的系统方案,并介绍了硬件结构及软件设计流程.在软件算法实现过程中,为提升数据处理速度,使用查找表的算法,使用最少的器件实现了原芯片的所有功能,并实现了产品模块化、小型化的目的.

  20. A New Measuring System of Phase and Amplitude Based on AD8302%基于AD8302芯片的新的幅相测量系统

    Institute of Scientific and Technical Information of China (English)

    曹兰娟

    2007-01-01

    介绍了利用美国ADI公司AD8302芯片测量RF/IF幅度和相位差的一种幅相测量系统.由于该芯片将精密匹配的两个对数检波器集成在一块芯片上,因而可将误差源及相关温度漂移减小到最低限度,可用于GSM(全球移动通信系统)、电力系统的阻波器、结合滤波器等领域.给出了该芯片的工作原理、模式及典型应用;介绍了该芯片在电力阻波器测试仪中的应用以及测量幅度、相位差、阻抗计算的方法.

  1. Fuzzy Logic-based Intelligent Scheme for Enhancing QoS of Vertical Handover Decision in Vehicular Ad-hoc Networks

    Science.gov (United States)

    Azzali, F.; Ghazali, O.; Omar, M. H.

    2017-08-01

    The design of next generation networks in various technologies under the “Anywhere, Anytime” paradigm offers seamless connectivity across different coverage. A conventional algorithm such as RSSThreshold algorithm, that only uses the received strength signal (RSS) as a metric, will decrease handover performance regarding handover latency, delay, packet loss, and handover failure probability. Moreover, the RSS-based algorithm is only suitable for horizontal handover decision to examine the quality of service (QoS) compared to the vertical handover decision in advanced technologies. In the next generation network, vertical handover can be started based on the user’s convenience or choice rather than connectivity reasons. This study proposes a vertical handover decision algorithm that uses a Fuzzy Logic (FL) algorithm, to increase QoS performance in heterogeneous vehicular ad-hoc networks (VANET). The study uses network simulator 2.29 (NS 2.29) along with the mobility traffic network and generator to implement simulation scenarios and topologies. This helps the simulation to achieve a realistic VANET mobility scenario. The required analysis on the performance of QoS in the vertical handover can thus be conducted. The proposed Fuzzy Logic algorithm shows improvement over the conventional algorithm (RSSThreshold) in the average percentage of handover QoS whereby it achieves 20%, 21% and 13% improvement on handover latency, delay, and packet loss respectively. This is achieved through triggering a process in layer two and three that enhances the handover performance.

  2. Predictors of compliance with a home-based exercise program added to usual medical care in preventing postmenopausal osteoporosis: an 18-month prospective study.

    Science.gov (United States)

    Mayoux-Benhamou, M A; Roux, C; Perraud, A; Fermanian, J; Rahali-Kachlouf, H; Revel, M

    2005-03-01

    This prospective 18-month study was designed to assess long-term compliance with a program of exercise aimed to prevent osteoporosis after an educational intervention and to uncover determinants of compliance. A total of 135 postmenopausal women were recruited by flyers or instructed by their physicians to participate in an educational session added to usual medical care. After a baseline visit and dual-energy X-ray absorptiometry, volunteers participated in a 1-day educational session consisting of a lecture and discussion on guidelines for appropriate physical activity and training in a home-based exercise program taught by a physical therapist. Scheduled follow-up visits were 1, 6, and 18 months after the educational session. Compliance with the exercise program was defined as an exercise practice rate 50% or greater than the prescribed training. The 18-month compliance rate was 17.8% (24/135). The main reason for withdrawal from the program was lack of motivation. Two variables predicted compliance: contraindication for hormone replacement therapy (odds ratio [OR] = 0.13; 95% confidence interval [95% CI], 0.04 to 0.46) and general physical function scores from an SF-36 questionnaire (OR=1.26; 95% CI, 1.03 to 1.5). To a lesser extent, osteoporosis risk, defined as a femoral T-score exercise, only a minority of postmenopausal women adhered to a home-based exercise program after 18 months.

  3. Detection and Prevention of Denial of Service (DoS Attacks in Mobile Ad Hoc Networks using Reputation-based Incentive Schemes

    Directory of Open Access Journals (Sweden)

    Mieso, K Denko

    2005-08-01

    Full Text Available Mobile ad hoc networks (MANETs are dynamic mobile networks that can be formed in the absence of any pre-existing communication infrastructure. In addition to node mobility, a MANET is characterized by limited resources such as bandwidth, battery power, and storage space. The underlying assumption in MANETs is that the intermediate nodes cooperate in forwarding packets. However, this assumption does not hold in commercial and emerging civilian applications. MANETs are vulnerable to Denial of Service (DoS due to their salient characteristics. There is a need to provide an incentive mechanism that can provide cooperation among nodes in the network and improve overall network performance by reducing DoS attacks. In this paper, we propose a reputation-based incentive mechanism for detecting and preventing DoS attacks. DoS attacks committed by selfish and malicious nodes were investigated. Our scheme motivates nodes to cooperate and excludes them from the network only if they fail to do so. We evaluated the performance of our scheme using the packet delivery ratio, the routing and communication overhead, and misbehaving node detection in a discrete event-simulation environment. The results indicate that a reputation-based incentive mechanism can significantly reduce the effect of DoS attacks and improve performance in MANETs.

  4. Automated Experiments on Ad Privacy Settings

    Directory of Open Access Journals (Sweden)

    Datta Amit

    2015-04-01

    Full Text Available To partly address people’s concerns over web tracking, Google has created the Ad Settings webpage to provide information about and some choice over the profiles Google creates on users. We present AdFisher, an automated tool that explores how user behaviors, Google’s ads, and Ad Settings interact. AdFisher can run browser-based experiments and analyze data using machine learning and significance tests. Our tool uses a rigorous experimental design and statistical analysis to ensure the statistical soundness of our results. We use AdFisher to find that the Ad Settings was opaque about some features of a user’s profile, that it does provide some choice on ads, and that these choices can lead to seemingly discriminatory ads. In particular, we found that visiting webpages associated with substance abuse changed the ads shown but not the settings page. We also found that setting the gender to female resulted in getting fewer instances of an ad related to high paying jobs than setting it to male. We cannot determine who caused these findings due to our limited visibility into the ad ecosystem, which includes Google, advertisers, websites, and users. Nevertheless, these results can form the starting point for deeper investigations by either the companies themselves or by regulatory bodies.

  5. Antiproton-Decelerator (AD)

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    When the Low-Energy Antiproton Ring (LEAR) was stopped in 1996, because of its costly operation, a cheaper way of continuing low-energy antiproton physics was sought. The Antiproton-Collector (AC), added in 1987 to the Antiproton Accumulator (AA) to provide a tenfold intensity increase, was converted into the Antiproton-Decelerator (AD). Antiprotons from the target at 3.5 GeV/c are decelerated to 100 MeV/c, and fast-ejected to the experiments. Major changes were necessary. Above all, the conversion from a constant-field machine to one with a magnetic cycle, modulating the field by an impressive factor 35. New systems for stochastic and electron cooling had to be added. Beam diagnostics at an intensity of only 2E7 antiprotons was a challenge. In 2000, the AD began delivery of antiprotons to the experiments.

  6. AdS_3: the NHEK generation

    CERN Document Server

    Bena, Iosif; Puhm, Andrea

    2015-01-01

    It was argued in arXiv:1203.4227 that the five-dimensional near-horizon extremal Kerr (NHEK) geometry can be embedded in String Theory as the infrared region of an infinite family of non-supersymmetric geometries that have D1, D5, momentum and KK monopole charges. We show that there exists a method to embed these geometries into asymptotically-AdS_3 x S^3/Z_N solutions, and hence to obtain infinite families of flows whose infrared is NHEK. This indicates that the CFT dual to the NHEK geometry is the IR fixed point of a Renormalization Group flow from a known local UV CFT and opens the door to its explicit construction.

  7. A Routing Algorithm Against Wormhole Attacks in Ad Hoc Network Based on Mobile Agents%Ad Hoc网络环境中避免虫洞攻击的路由算法

    Institute of Scientific and Technical Information of China (English)

    张毅; 王小非; 夏学知

    2007-01-01

    根据Ad Hoc网络环境中虫洞攻击的特点,提出了一种基于移动Agent的路由算法.移动Agent在网络中根据一定的运行策略进行移动,并不断地和所经历的节点进行数据交换,由此了解网络中所有节点的路由连接信息,在此基础上形成一个节点信息矩阵表,并根据所形成的矩阵表,采用图论中的广度优先搜索算法来决定数据报文的最佳传输路径,同时产生若干条备用路径,快速地发送数据报文.仿真实验结果表明,由于各节点通过矩阵表可以充分了解网络中每个节点的地理位置,因此可以很好地抵御虫洞的攻击;同时由于仅使用很少的Agent便获得较多的全局信息,因此可以大大地减少维持节点信息而产生的开销,具有很高的效率和鲁棒性.

  8. An Improved Airspace Encounter Detection Algorithm Based on ADS-B%一种改进的基于ADS-B信息的空域冲突检测算法

    Institute of Scientific and Technical Information of China (English)

    王啸; 赵修斌

    2013-01-01

    研究了机载防撞系统中基于ADS-B信息的空域冲突检测算法,该算法的目的在于为飞行员对可能存在的空域冲突提出告警,使其在冲突发生前有充足的时间做出反应.定义了CAZ和PAZ两个冲突告警区域后,在匀转弯速率航迹外推方法下,根据空域遭遇模型中两遭遇飞机的相对角度的概率统计数据,对预测PAZ冲突的告警区域门限添加了一个压缩系数,使其成为一个椭圆;并分析了不同压缩系数对最后PAZ冲突预警的性能的影响.仿真分析表明,由于CAZ预警存在11.69%的漏警率,使用PAZ预警作为CAZ预警的补充是十分有益和必要的,添加压缩系数实际上通过牺牲一定的告警时间来换取更高的正确预警概率并降低错误预警概率,根据需要使用不同的压缩系数可以达到更好的效果.

  9. A Plasmodium Promiscuous T Cell Epitope Delivered within the Ad5 Hexon Protein Enhances the Protective Efficacy of a Protein Based Malaria Vaccine.

    Directory of Open Access Journals (Sweden)

    Jairo Andres Fonseca

    Full Text Available A malaria vaccine is a public health priority. In order to produce an effective vaccine, a multistage approach targeting both the blood and the liver stage infection is desirable. The vaccine candidates also need to induce balanced immune responses including antibodies, CD4+ and CD8+ T cells. Protein-based subunit vaccines like RTS,S are able to induce strong antibody response but poor cellular reactivity. Adenoviral vectors have been effective inducing protective CD8+ T cell responses in several models including malaria; nonetheless this vaccine platform exhibits a limited induction of humoral immune responses. Two approaches have been used to improve the humoral immunogenicity of recombinant adenovirus vectors, the use of heterologous prime-boost regimens with recombinant proteins or the genetic modification of the hypervariable regions (HVR of the capsid protein hexon to express B cell epitopes of interest. In this study, we describe the development of capsid modified Ad5 vectors that express a promiscuous Plasmodium yoelii T helper epitope denominated PyT53 within the hexon HVR2 region. Several regimens were tested in mice to determine the relevance of the hexon modification in enhancing protective immune responses induced by the previously described protein-based multi-stage experimental vaccine PyCMP. A heterologous prime-boost immunization regime that combines a hexon modified vector with transgenic expression of PyCMP followed by protein immunizations resulted in the induction of robust antibody and cellular immune responses in comparison to a similar regimen that includes a vector with unmodified hexon. These differences in immunogenicity translated into a better protective efficacy against both the hepatic and red blood cell stages of P. yoelii. To our knowledge, this is the first time that a hexon modification is used to deliver a promiscuous T cell epitope. Our data support the use of such modification to enhance the immunogenicity

  10. Value-Added Business Based On Small Scale Of Fisheries A Case Study On Nortern And Shouthern Coasts Of Java Lamongan And Pelabuhanratu Regency Indonesia

    Directory of Open Access Journals (Sweden)

    Budi Wardono

    2015-08-01

    Full Text Available The development of fisheries sector is intended to improve the role of creating a strong linkage with other sectors by increasing the value added absorbing labor forces and increasing peoples income so that this can make the economy grow well. The value added is a value that increases due to a commodity that has been processed transported or stored in a production. Lamongan and Pelabuhanratu regencies are one of fisheries centers on the north and the south coast of Java Island. The aim of this research was to know the value added and the business margin of fisheries from the processing and marketing aspects. The research was carried out in two locations Northern coast Lamongan regencies and Shouther coasts Pelabuhanratu regencies Indoneisa. The data used were primary data the people involved in the business including fishing marketing and processing product. The results showed that the process of fisheries product yielded the value added and margin that were created from the incorporation of business benefit added input contribution other input and direct reward for the labor forces. The value added and the business margin of product processing can reach 2 to 3 fold from the main input value. The value added and the business margin of fisheries product processing were very big. This was the source of economy growth there. The effort to develop the business of fisheries product processing in the small scale need to be supported with various programs especially in the market access and funding.

  11. Enthalpy and the Mechanics of AdS Black Holes

    CERN Document Server

    Kastor, David; Traschen, Jennie

    2009-01-01

    We present geometric derivations of the Smarr formula for static AdS black holes and an expanded first law that includes variations in the cosmological constant. These two results are further related by a scaling argument based on Euler's theorem. The key new ingredient in the constructions is a two-form potential for the static Killing field. Surface integrals of the Killing potential determine the coefficient of the variation of the cosmological constant in the first law. This coefficient is proportional to a finite, effective volume for the region outside the AdS black hole horizon, which can also be interpreted as minus the volume excluded from a spatial slice by the black hole horizon. This effective volume also contributes to the Smarr formula. Since the cosmological constant is naturally thought of as a pressure, the new term in the first law has the form of effective volume times change in pressure that arises in the variation of the enthalpy in classical thermodynamics. This and related arguments sug...

  12. Quantum cat map dynamics on AdS$_2$

    CERN Document Server

    Axenides, Minos; Nicolis, Stam

    2016-01-01

    We present a toy model for the chaotic unitary scattering of single particle wave packets on the radial AdS$_2$ geometry of extremal BH horizons. Based on our recent work for the discretization of the AdS$_2$ space-time, which describes a finite and random geometry, by modular arithmetic, we investigate the validity of the eigenstate thermalization hypothesis (ETH), as well as that of the fast scrambling time bound conjecture (STB), for an observer with time evolution operator the quantum Arnol'd cat map (QACM). We find that the QACM, while possessing a linear spectrum, has eigenstates, which can be expressed in closed form, are found to be random and to satisfy the assumptions of the ETH.The implications are that the dynamics is described by a chaotic, unitary, single particle S-matrix, which completely delocalizes and randomizes initial gaussian wave packets . Applying results obtained by Dyson and Falk for the periods of the Arnol'd Cat Map(ACM),which are related to its mixing time, we also find that the t...

  13. AdCell: Ad Allocation in Cellular Networks

    CERN Document Server

    Alaei, Saeed; Liaghat, Vahid; Pei, Dan; Saha, Barna

    2011-01-01

    With more than four billion usage of cellular phones worldwide, mobile advertising has become an attractive alternative to online advertisements. In this paper, we propose a new targeted advertising policy for Wireless Service Providers (WSPs) via SMS or MMS- namely {\\em AdCell}. In our model, a WSP charges the advertisers for showing their ads. Each advertiser has a valuation for specific types of customers in various times and locations and has a limit on the maximum available budget. Each query is in the form of time and location and is associated with one individual customer. In order to achieve a non-intrusive delivery, only a limited number of ads can be sent to each customer. Recently, new services have been introduced that offer location-based advertising over cellular network that fit in our model (e.g., ShopAlerts by AT&T) . We consider both online and offline version of the AdCell problem and develop approximation algorithms with constant competitive ratio. For the online version, we assume tha...

  14. 基于ECC的移动自组网成员控制方案%Member Control Scheme of Mobile Ad Hoc Networks Based on ECC

    Institute of Scientific and Technical Information of China (English)

    耿永军; 陈红军; 郑明辉

    2012-01-01

    A distributed key generation protocol is proposed by ECC based on Peterson distributed key generation scheme, which can resist malicious attack of outer or inner node. A secure member control sckeme is also proposed by using threshold digital sisgnature. By analyzing the scheme's performance and security, a conclusion is drawn that the member control policy is suitable for mobile Ad Hoc networks of limited resource devices.%基于Pederson分布式密钥产生方案,采用椭圆曲线密码体制提出一个分布式密钥产生协议,该方案高效且能抵制内外恶意节点的攻击,并采用门限数字签名方案给出一个安全的移动自组网的成员控制方案.通过方案的性能和安全性分析得出结论,该成员控制策略非常适合于资源受限的移动自组网.

  15. Intelligent algorithms for persistent and pervasive sensing in systems comprised of wireless ad hoc networks of ground-based sensors and mobile infrastructures

    Science.gov (United States)

    Hortos, William S.

    2007-04-01

    With the development of low-cost, durable unmanned aerial vehicles (UAVs), it is now practical to perform persistent sensing and target tracking autonomously over broad surveillance areas. These vehicles can sense the environment directly through onboard active sensors, or indirectly when aimed toward ground targets in a mission environment by ground-based passive sensors operating wirelessly as an ad hoc network in the environment. The combination of the swarm intelligence of the airborne infrastructure comprised of UAVs with the ant-like collaborative behavior of the unattended ground sensors creates a system capable of both persistent and pervasive sensing of mission environment, such that, the continuous collection, analysis and tracking of targets from sensor data received from the ground can be achieved. Mobile software agents are used to implement intelligent algorithms for the communications, formation control and sensor data processing in this composite configuration. The enabling mobile agents are organized in a hierarchy for the three stages of processing in the distributed system: target detection, location and recognition from the collaborative data processing among active ground-sensor nodes; transfer of the target information processed on the ground to the UAV swarm overhead; and formation control and sensor activation of the UAV swarm for sustained ground-target surveillance and tracking. Intelligent algorithms are presented that can adapt to the operation of the composite system to target dynamics and system resources. Established routines, appropriate to the processing needs of each stage, are selected as preferred based on their published use in similar scenarios, ability to be distributively implemented over the set of processors at system nodes, and ability to conserve the limited resources at the ground nodes to extend the lifetime of the pervasive network. In this paper, the performance of this distributed, collaborative system concept for

  16. Gemcitabine-Based Chemogene Therapy for Pancreatic Cancer Using Ad-dCK::UMK GDEPT and TS/RR siRNA Strategies

    Directory of Open Access Journals (Sweden)

    Soukaina Réjiba

    2009-07-01

    Full Text Available Gemcitabine is a first-line agent for advanced pancreatic cancer therapy. However, its efficacy is often limited by its poor intracellular metabolism and chemoresistance. To exert its antitumor activity, gemcitabine requires to be converted to its active triphosphate form. Thus, our aim was to improve gemcitabine activation using gene-directed enzyme prodrug therapy based on gemcitabine association with the deoxycytidine kinase::uridine monophosphate kinase fusion gene (dCK::UMK and small interference RNA directed against ribonucleotide reductase (RRM2 and thymidylate synthase (TS. In vitro, cytotoxicity was assessed by 3-[4,5-dimethylthiazol-2-yl]-3,5-diphenyl tetrazolium bromide and [3H]thymidine assays. Apoptosis-related gene expression and activity were analyzed by reverse transcription-polymerase chain reaction, Western blot, and ELISA. For in vivo studies, the treatment efficacy was evaluated on subcutaneous and orthotopic pancreatic tumor models. Our data indicated that cell exposure to gemcitabine induced a down-regulation of dCK expression and up-regulation of TS and RR expression in Panc1-resistant cells when compared with BxPc3- and HA-hpc2-sensitive cells. The combination of TS/RRM2 small interference RNA with Ad-dCK::UMK induced a 40-fold decrease of gemcitabine IC50 in Panc1 cells. This strong sensitization was associated to apoptosis induction with a remarkable increase in TRAIL expression and a diminution of gemcitabine-induced nuclear factor-κB activity. In vivo, the gemcitabine-based tritherapy strongly reduced tumor volumes and significantly prolonged mice survival. Moreover, we observed an obvious increase of apoptosis and decrease of cell proliferation in tumors receiving the tritherapy regimens. Together, these findings suggest that simultaneous TS/RRM2-gene silencing and dCK::UMK gene overexpression markedly improved gemcitabine's therapeutic activity. Clearly, this combined strategy warrants further investigation.

  17. Facilities Management and Added Value

    DEFF Research Database (Denmark)

    Jensen, Per Anker

    2010-01-01

    Aim: This paper aims to present different models of the concept of the added value of Facilities Management (FM), including the FM Value Map, which forms the basis of research group in EuroFM, and to present some of the results of this research collaboration. Approach and methodology: The paper...... on the aimed output) and the internal resource based view (with a focus on the input from FM and RE). Good relationship management and building on trust shows to be equally important as delivering the agreed services. In order to measure the multi-dimensional components of adding value both qualitative...... is based on literature reviews of the most influential journals within the academic fields of FM, Corporate Real Estate Management and Business to Business Marketing and discussions between participants of the research group working on a further exploration and testing of the FM Value Map. Conclusions...

  18. The impact of net value added on predicting the earnings and operating cash flow: An empirical study based on Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Omid Imani Khoshkhoo

    2013-12-01

    Full Text Available Information content of earnings and its components and other issues except the earnings such as the operating cash flow (OCF have been tested widely in the accounting and finance literature. Since they have had an essential role in most cases including financial reporting, contracts and evaluation models, specifying the items and financial variables that have had a significant relationship with these two variables are expected to be of utmost importance. One example of these variables and indicators is the value added. Although this variable has an economic concept, reporting of value added to the beneficiaries of business entity as the value-added statement has been observed in the field of accounting theories for many years. The main objective of this study was to investigate the effect of net value added (NVA as the basic result of value-added statement in predicting the accounting earnings and operating cash flow. For this purpose, the relationship of changes in net value added with the changes in accounting earnings and operating cash flow of listed companies in Tehran Stock Exchange from 2007 to 2011 was tested. Firstly the Single variable cross-sectional regression was analyzed and then the panel data analysis with the PLS technique was used to do a pooled analysis. The results of testing research hypothesis imply the significant relationship between changes in net value added and accounting earnings in the listed companies as cross-sectional and pooled forms. The results showed no significant relationship between changes in net value added and operating cash flow in the listed companies neither in cross-sectional nor pooled form.

  19. Dynamic ad hoc networks

    CERN Document Server

    Rashvand, Habib

    2013-01-01

    Motivated by the exciting new application paradigm of using amalgamated technologies of the Internet and wireless, the next generation communication networks (also called 'ubiquitous', 'complex' and 'unstructured' networking) are changing the way we develop and apply our future systems and services at home and on local, national and global scales. Whatever the interconnection - a WiMAX enabled networked mobile vehicle, MEMS or nanotechnology enabled distributed sensor systems, Vehicular Ad hoc Networking (VANET) or Mobile Ad hoc Networking (MANET) - all can be classified under new networking s

  20. Adding a Social Marketing Campaign to a School-Based Nutrition Education Program Improves Children's Dietary Intake: A Quasi-Experimental Study.

    Science.gov (United States)

    Blitstein, Jonathan L; Cates, Sheryl C; Hersey, James; Montgomery, Doris; Shelley, Mack; Hradek, Christine; Kosa, Katherine; Bell, Loren; Long, Valerie; Williams, Pamela A; Olson, Sara; Singh, Anita

    2016-08-01

    Evidence supports the use of social marketing campaigns to improve nutrition knowledge and reinforce the effects of nutrition education programs. However, the additional effects of parent-focused social marketing with nutrition education have received little attention. Our aim was to assess the impact of the Iowa Nutrition Network's school-based nutrition education program (Building and Strengthening Iowa Community Support for Nutrition and Physical Activity [BASICS]) and the benefits of adding a multichannel social marketing intervention (BASICS Plus) to increase parent-directed communication. A quasi-experimental design with three study conditions compared a school-based nutrition education program (BASICS) with a school-based and social marketing intervention (BASICS Plus) and a no-treatment comparison group. The study included 1,037 third-grade students attending 33 elementary schools and their parents. Measures included parents' reports of their children's in-home consumption of fruits and vegetables (F/V) and use of low-fat/fat-free milk. Data on F/V were collected using a modified version of the University of California Cooperative Extension Food Behavior Checklist; and data on milk use were collected using two questions from the National Health and Nutrition Examination Survey. Multilevel, mixed-effect regression models that account for correlation within repeated measures and children within school were used to compare the mean change over time in the outcome variable for one study group with the mean change over time for another study group. Children in BASICS increased mean consumption of fruit by 0.16 cups (P=0.04) compared with children in the comparison group. Children in BASICS Plus increased mean consumption of fruit by 0.17 cups (P=0.03) and mean consumption of vegetables by 0.13 cups (P=0.02). Children in BASICS Plus were 1.3 times (P=0.05) more likely to use low-fat/fat-free milk than children in either the BASICS group or the comparison group