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1.
In the request-based scheme, a patching channel is initiated on arrival of a request in an interarrival time of two adjacent multicast channels. If two requests are received in a short duration in an interarrival time, two patching channels are needed to service them. Both these channels deliver almost the same data, thus, wasting the bandwidth. This problem may be addressed in two ways: using higher level patching technique, or forcing the first request to wait for the second one. Using higher level patching technique makes the system more complex and thus usually not preferred. In the second case, the bandwidth usage certainly reduces, but the length of the waiting time by the first request for the second request is the main issue. In this paper, this issue is addressed by dividing the video duration into uniform time slots such that there is at least one request in a time slot for initiating the patching channel. The proposed scheme is named as Video Data Delivery using Slotted Patching. In this scheme, the patching channels download much less video data than the request-based scheme and thus require less bandwidth. This scheme may not provide immediate services to all users unlike the request-based scheme, but the user's waiting can be made arbitrarily small without using much resources unlike the request-based scheme.  相似文献   
2.
Summary A new group of low-molecular weight channel-forming oligo(hydroxybutyric acids) (cPHBs, 1 with n = 8–30; main component MW ≈ 1300 dalton) was isolated from microorganisms of different origin. Inclusion bodies were electron-microscopically visible in cells in the state of autolysis, not in cells in the exponential phase of growth. cPHB and high-molecular poly(l3-hydroxybutyric acid) (sPHB) is cleaved by phenylethylamine and forms the corresponding monomeric hydroxybutyramide and – under drastic conditions, the crotylamide. One of these compounds, the 3-hydroxy-N-phenethyl-butyramide (5), was isolated as a new natural product now. Received: 28 March 2002/Revised version: 26 July 2002/ Accepted: 26 July 2002 RID="*" ID="*"Marine Bakterien, XVII. XVI: R.P. Maskey, R.N. Asolkar, E. Helmke, and H. Laatsch, Chalcomycin B, a new antibiotic from a marine Streptomyces sp. B7064. J. Antibiot., submitted 2002 Correspondence to Hartmut Laatsch, e-mail: hlaatsc@gwdg.de, Fax: +49-551-399660  相似文献   
3.
This paper emphasizes on establishment of traceability for the strain measuring data acquisition system in terms of voltage. If this amplifier’s output voltage is not calibrated then traceability chain breaks. To complete the traceability chain, the amplifier’s output voltage has been calibrated for corresponding strain. The sensitivity is calculated using calibration results and further used to feed in data acquisition system to display the result in terms of force/strain.  相似文献   
4.
The lifetime of a network can be increased by increasing the network energy. The network energy can be increased either increasing the number of sensors or increasing the initial energy of some sensors without increasing their numbers. Increasing network energy by deploying extra sensors is about ten times costlier than that using some sensors of high energy. Increasing the initial energy of some sensors leads to heterogeneous nodes in the network. In this paper, we propose a multilevel heterogeneous network model that is characterized by two types of parameters: primary parameter and secondary parameters. The primary parameter decides the level of heterogeneity by assuming the values of secondary parameters. This model can describe a network up to nth level of heterogeneity (n is a finite number). We evaluate the network performance by applying the HEED, a clustering protocol, on this model, naming it as MLHEED (Multi Level HEED) protocol. For n level of heterogeneity, this protocol is denoted by MLHEED-n. The numbers of nodes of each type in any level of heterogeneity are determined by the secondary model parameter. The MLHEED protocol (for all level heterogeneity) considers two variables, i.e., residual energy and node density, for deciding the cluster heads. We also consider fuzzy implementation of the MLHEED in which four variables are used to decide the cluster heads: residual energy, node density, average energy, and distance between base station and the sensor nodes. In this work, we illustrate the network model up to seven levels (\(1\le n\le 7\)). Experimentally, as the level of heterogeneity increases, the rate of energy dissipation decreases and hence the nodes stay alive for longer time. The MLHEED-m, \(m=2,3,4,5,6,7\), increase the network lifetime by \(73.05, 143.40, 213.17, 267.90, 348.60, 419.10\,\%\), respectively, by increasing the network energy as \(40, 57, 68.5, 78, 84, 92.5\,\%\) with respect to the original HEED protocol. In case of fuzzy implementation, the MLHEEDFL-m, \(m=2,3,4,5,6,7,\) increases the network lifetime by \(282.7, 378.5, 435.78, 498.50, 582.63, 629.79\,\%\), respectively, corresponding to the same increase in the network energy as that of the MLHEED (all levels) with respect to the original HEED. The fuzzy implementation of the HEED, MLHEEDFL-1, increases the network lifetime by \(176.6\,\%\) with respect to the original HEED with no increase in the network energy.  相似文献   
5.
In adaptive segment-based patching scheme, the video is divided into fixed number of segments, which are transmitted over the server channels. For efficient transmission of the video segments, the server channels are classified into two types – regular and patching channels. A regular channel generally transmits fixed number of segments and a patching channel helps transmitting those segments that cannot be provided by any regular channel to the users. The number of segments transmitted by the first regular channel is decided by the number of regular channels that are allocated to the video by the video server. Other regular channels transmit pre-specified number of segments. This scheme estimates the bandwidth of the patching channels based on the requests received at the video server in terms of fixed time intervals, called time slots. The bandwidth estimation in this scheme is less accurate because for multiple requests received in a time slot more than one patching channels are used. Second, the probability distribution considered in this scheme does not satisfy the basic rule, i.e., the sum of all probabilities is not 1. In this paper, we address these issues and propose a new protocol named as Segmented Patching Broadcasting Protocol for Video Data. The average server bandwidth allocated to the patching channels is much less as compared to the adaptive segment-based patching scheme because only one patching channel is sufficient for any number of requests received in a time slot.  相似文献   
6.
Progress in both speech and language processing has spurred efforts to support applications that rely on spoken rather than written language input. A key challenge in moving from text-based documents to such spoken documents is that spoken language lacks explicit punctuation and formatting, which can be crucial for good performance. This article describes different levels of speech segmentation, approaches to automatically recovering segment boundary locations, and experimental results demonstrating impact on several language processing tasks. The results also show a need for optimizing segmentation for the end task rather than independently.  相似文献   
7.
The study explores in vitro antifungal and aflatoxin B1 inhibitory potency of chemically characterised Lippia origanoides EO (LOEO) encompassed in chitosan nanoparticle (CS-LOEO-Np). CS-LOEO-Np was physico-chemically characterised through XRD, SEM and FTIR analyses. CS-LOEO-Np exhibited improved antifungal and AFB1 inhibitory efficacy (0.05 and 0.045 µl mL−1, respectively) in contrast to LOEO (0.30 and 0.25 µl mL−1, respectively). Bioactivity of LOEO loaded nanoparticle was enhanced as reflected by depletion in ergosterol content, rapid cellular ion release and reduced methylglyoxal content. IC50 value equivalent to 4.17 µl mL−1 displayed better antioxidant potency of CS-LOEO-Np as compared to LOEO (IC50 = 6.20 µl mL−1). CS-LOEO-Np preserved sensorial attributes of stored Nigella sativa (model food matrix) samples and have higher lethal toxicity dose, that is LD50 = 8832 mg kg−1. Hence, CS-LOEO-Np could serve as novel green candidate to ensure food security with better nutritional and sensorial features.  相似文献   
8.
ABSTRACT

As more and more development-related networks, both instructional and industry related, are being attached to the Internet, the need for protection from hackers becomes evident. This is largely due to the fact that security breaches have reached epidemic proportions. The article therein examines these issues as well as presents a case study for a basic firewall configuration. The logic behind the case study is based on four different modules containing one or more sections: environmental, forward rules, allow ping, and post-routing rules. A figure and source code is provided to indicate how the logic would appear once the plan had been implemented. The example was designed as such in hopes that a more sophisticated and usable product could emerge. In addition, this template could be considered a useful learning and/or teaching resource when teaching basic firewall configurations.  相似文献   
9.
Single-particle characterization of Antarctic aerosols was performed to investigate the impact of marine biogenic sulfur species on the chemical compositions of sea-salt aerosols in the polar atmosphere. Quantitative energy-dispersive electron probe X-ray microanalysis was used to characterize 2900 individual particles in 10 sets of aerosol samples collected between March 12 and 16, 2009 at King Sejong Station, a Korean scientific research station located at King George Island in the Antarctic. Two size modes of particles, i.e., PM(2.5-10) and PM(1.0-2.5), were analyzed, and four types of particles were identified, with sulfur-containing sea-salt particles being the most abundant, followed by genuine sea-salt particles without sulfur species, iron-containing particles, and other species including CaCO(3)/CaMg(CO(3))(2), organic carbon, and aluminosilicates. When a sulfur-containing sea-salt particle showed an atomic concentration ratio of sulfur to sodium of >0.083 (seawater ratio), it is regarded as containing nonsea-salt sulfate (nss-SO(4)(2-)) and/or methanesulfonate (CH(3)SO(3)(-)), which was supported by attenuated total reflection Fourier transform-infrared imaging measurements. These internal mixture particles of sea-salt/CH(3)SO(3)(-)/SO(4)(2-) were very frequently encountered. As nitrate-containing particles were not encountered, and the air-masses for all of the samples originated from the Pacific Ocean (based on 5-day backward trajectories), the oxidation of dimethylsulfide (DMS) emitted from phytoplanktons in the ocean is most likely to be responsible for the formation of the mixed sea-salt/CH(3)SO(3)(-)/SO(4)(2-) particles.  相似文献   
10.
One of the important protocols for increasing the network lifetime in wireless sensor networks (WSNs) is hybrid energy efficient distributed (HEED) protocol. This protocol considers two parameters for deciding the cluster heads, i.e., residual energy and node density and has been designed for the homogeneous WSNs. In this paper, we consider the implementation of HEED for a heterogeneous network. Depending upon the type of nodes, it defines one-level, two-level, and three-level heterogeneity and accordingly the implementation of HEED is referred to as hetHEED-1, hetHEED-2, and hetHEED-3, respectively. We also consider one more parameter, i.e., distance and apply fuzzy logic to determine the cluster heads and accordingly the hetHEED-1, hetHEED-2, and hetHEED-3 are named as HEED-FL, hetHEED-FL-2, hetHEED-FL-3, respectively. The simulation results show that as the level of heterogeneity increases in the network, the nodes remain alive for longer time and the rate of energy dissipation decreases. And also, increasing the heterogeneity level helps sending more packets to the base station and increases the network lifetime. The increase in the network energy increases the network lifetime manifold. In fact, using fuzzy logic, the network lifetime increases by 114.85 % that of the original HEED without any increase in the network energy. Thus, the hetHEED-FL-3 provides the longest lifetime (387.94 % increase) in lifetime at the cost of 19 % increase in network energy), sends maximum number of packets to the base station, and has minimum rate of energy dissipation.  相似文献   
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