Neighbour replica affirmative adaptive failure detection and autonomous recovery

High availability is an important property for current distributed systems. The trends of current distributed systems such as grid computing and cloud computing are the delivery of computing as a service rather than a product. Thus, current distributed systems rely more on the highly available systems. The potential to fail-stop failure in distributed computing systems is a significant disruptive factor for high availability distributed system. Hence, a new failure detection approach in a distributed system called Affirmative Adaptive Failure Detection (AAFD) is introduced. AAFD utilises heartbeat for node monitoring. Subsequently, Neighbour Replica Failure Recovery(NRFR) is proposed for autonomous recovery in distributed systems. AAFD can be classified as an adaptive failure detector, since it can adapt to the unpredictable network conditions and CPU loads. NRFR utilises the advantages of the neighbour replica distributed technique (NRDT) and combines with weighted priority selection in order to achieve high availability, since automatic failure recovery through continuous monitoring approach is essential in current high availability distributed system. The environment is continuously monitored by AAFD while auto-reconfiguring environment for automating failure recovery is managed by NRFR. The NRFR and AAFD are evaluated through virtualisation implementation. The results showed that the AAFD is 30% better than other detection techniques. While for recovery performance, the NRFR outperformed the others only with an exception to recovery in two distributed technique (TRDT). Subsequently, a realistic logical structure is modelled in complex and interdependent distributed environment for NRDT and TRDT. The model prediction showed that NRDT availability is 38.8% better than TRDT. Thus, the model proved that NRDT is the ideal replication environment for practical failure recovery in complex distributed systems. Hence, with the ability to minimise the Mean Time To Repair (MTTR) significantly and maximise Mean Time Between Failure (MTBF), this research has accomplished the goal to provide high availability self sustainable distributed system

Distributed Object Medical Imaging Model

Abstract- Digital medical informatics and images are commonly used in hospitals today,. Because of the interrelatedness of the radiology department and other departments, especially the intensive care unit and emergency department, the transmission and sharing of medical images has become a critical issue. Our research group has developed a Java-based Distributed Object Medical Imaging Model(DOMIM) to facilitate the rapid development and deployment of medical imaging applications in a distributed environment that can be shared and used by related departments and mobile physiciansDOMIM is a unique suite of multimedia telemedicine applications developed for the use by medical related organizations. The applications support realtime patients’ data, image files, audio and video diagnosis annotation exchanges. The DOMIM enables joint collaboration between radiologists and physicians while they are at distant geographical locations. The DOMIM environment consists of heterogeneous, autonomous, and legacy resources. The Common Object Request Broker Architecture (CORBA), Java Database Connectivity (JDBC), and Java language provide the capability to combine the DOMIM resources into an integrated, interoperable, and scalable system. The underneath technology, including IDL ORB, Event Service, IIOP JDBC/ODBC, legacy system wrapping and Java implementation are explored. This paper explores a distributed collaborative CORBA/JDBC based framework that will enhance medical information management requirements and development. It encompasses a new paradigm for the delivery of health services that requires process reengineering, cultural changes, as well as organizational changes

A review on cloud based knowledge management in higher education institutions

Knowledge Management (KM) is widely discussed by researcher and attracts many enterprisers to extract, dispense and use information in a systematic way under Knowledge Management System (KMS). New technology adoption within the knowledge management system is one of the core issue, identified by researcher and underlined as future research agenda. Cloud computing becomes the most adoptable choice for enterprisers to reduce infrastructure and maintenance cost by shifting business on the cloud. Higher Education Institutions (HEIs) are more enthusiastic about knowledge management due to its primary goal of knowledge creation and sharing. Cloud based knowledge management attract higher education institutions by changing the educational method and objectives due to innovative trends in technology. This exploratory research based on literature review for cloud-based knowledge management, targeting higher education institutions. This study highlights the benefits and challenges associated with cloud-based knowledge management system and its impact on knowledge

A Design and Implementation of Cluster Heartbeat Network for Efficient Fault Detection

To achieve fault tolerance in a server cluster, fault detection capability is a primary prerequisite. Efficient fault detection is prompt, correct and complete. This paper revisited the technique called Reactive Failure Detection (RFD) that dynamically predicts a heartbeat delay from a cluster node. We also identified the requirements to deploy RFD in actual servers. A new cluster heartbeat network with concurrency is proposed to use push and pull interaction during live monitoring and determining node’s status. The prototype of the new model is tested on a platform running multiple independent web applications and analyzed for its implementation and design correctness

Two-photon photoluminescence induced defects on InGaN crystal and light emitting diodes

Two-photon excitation techniques used in fabricating lines defects were done on a light emitting diode chip. Simultaneous detection of a quenched wide-gap semiconductor crystal has been observed using single- and two-photon photoluminescence. It was found at the quenched area, single-photon excitation gives photoluminescence read-out compared to two-photon excitation which no photoluminescence detected at the bandgap wavelength. This is due to the excitation states which the transition of electron for two-photon excitation to occur have been demolished by the annealing of the sample which involved two-photon quenching process. The dependency of excitation power with respective photoluminescence is elaborated to confirmed the single- and two-photon excitation photoluminescence methods

Community social capital in Malaysia: A pilot study

Social capital is a vital concept in identifying resources in the social network, which has the capability to be used to improve life quality and to facilitate the society development process. It emerges in the form of individual asset and needs to be analyzed through collective lifestyle or a community. An initial process has been explored to identify social capital components. The outcome is translated into an instrument comprising of six social capital components based on survey items and past studies namely participation in community activities, proactivity in the social context, neighborhood connections, multi-racial tolerance, a sense of trust and protection, and life values. A pilot study involving 41 respondents was carried out in several neighboring areas in the northern part of Malaysia. The study results show that all six components have a high internal reliability value. These components of social capital are categorized into three levels namely low, moderate and high. The findings demonstrate that the majority of the four components are at the high level. They are participation in community activities, neighborhood connections, multi-racial tolerance, and, a sense of trust and protection whereas majority of the respondents for the components of proactivity in the social context and life values is at the moderate level

Measurement of copper nanoparticle concentration using surface plasmon resonance

In this work, the concentration of copper nanoparticles in virgin coconut oil were measured using surface plasmon resonance technique, and the gold layer was modified by using Polypyrrole Multi-Walled Carbon Nanotube composite layer. The concentration of nanoparticles and angle of resonance shifted from 0.066 mg/L to 0.71 mg/L and from 64.779° to 64.96°, respectively, and the sensitivity of sensor is about 0.01 mg/L

Linewidth characteristics of un-cooled fiber grating Fabry–Perot laser controlled by the external optical feedback

The effect of external optical feedback (OFB) on the linewidth characteristics of un-cooled laser module is theoretically investigated. This laser that consists of a Fabry–Perot (FP) laser diode and fiber Bragg grating (FBG) realizes stable operation and relatively low-cost solution. The effects of external OFB and temperature on linewidth are calculated according to their effect on threshold carrier density (Nth). The temperature dependence (TD) of linewidth characteristics is calculated according to TD of laser parameters instead of well-known Parkovin relationship. Results show that, linewidth decreases as the external OFB reflectivity (Rext) increases. A narrow linewidth which is less than 3 kHz is obtained for Rext ≥ 0.5. In addition, the linewidth is not largely affected by temperature as compared to the DFB lasers. Also, we found that the linewidth temperature coefficient is 0.04 kHz/°C, which is small enough in comparison to 18.5 kHz/°C for the DFB laser

Relative Intensity Noise Reduction by Optimizing Fiber Grating Fabry-Perot Laser Parameters.

A set of nonlinear rate equations that can describe an external cavity laser with any arbitrary external optical feedback (OFB) level are derived. A comprehensive study on the relative intensity noise (RIN) characteristics of a fiber grating Fabry-Perot is performed numerically. In this paper, fiber Bragg grating (FBG) is used as a wavelength lasing selective element to control the external OFB level, thereby control the RIN. In addition to the external OFB level, the effect of other external cavity parameters such as temperature, injection current, cavity volume, gain compression factor, and FBG parameters on RIN characteristics is investigated. The temperature dependence (TD) of RIN is calculated according to TD of laser parameters instead of well-known Parkove relationship. Results show that by optimization, the peak value of the RIN can be reduced down to around -150 dB/Hz. The optimum and the shortest external cavity length that provides the minimum RIN is found to be around 3.1 cm. In addition, by optimization, the relaxation oscillation frequency of RIN spectra is shifted toward around 5.6 GHz

Survey on replication techniques for distributed system

Distributed systems mainly provide access to a large amount of data and computational resources through a wide range of interfaces. Besides its dynamic nature, which means that resources may enter and leave the environment at any time, many distributed systems applications will be running in an environment where faults are more likely to occur due to their ever-increasing scales and the complexity. Due to diverse faults and failures conditions, fault tolerance has become a critical element for distributed computing in order for the system to perform its function correctly even in the present of faults. Replication techniques primarily concentrate on the two fault tolerance manners precisely masking the failures as well as reconfigure the system in response. This paper presents a brief survey on different replication techniques such as Read One Write All (ROWA), Quorum Consensus (QC), Tree Quorum (TQ) Protocol, Grid Configuration (GC) Protocol, Two-Replica Distribution Techniques (TRDT), Neighbour Replica Triangular Grid (NRTG) and Neighbour Replication Distributed Techniques (NRDT). These techniques have its own redeeming features and shortcoming which forms the subject matter of this survey