Cooperative detection and protection for Interest flooding attacks in named data networking

Named data networking (NDN) is a new emerging architecture for future network, which may be a substitute of the current TCP/IP‐based network, for the content‐oriented data request mode becoming the future trend of development. The security of NDN has attracted much attention, as an implementation of next‐generation Internet architecture. Although NDN is immune to most current attack, it cannot resist the distributed denial of service like attack – Interest flooding attack (IFA) – effectively. IFA takes advantages of the forwarding mechanism of NDN, flooding a large number of malicious Interest packets at quite a high rate, and exploits the network resources, which may cause the paralysis of the network. Taking into account the severity of the destruction, we propose an algorithm to counter such new type of attack. We analyze three properties of IFA, and use them to judge and filter Interest packets. Vector space model and Markov model are used in our method to realize a cooperative detection. Meanwhile, we present the retransmission forwarding mechanism to ensure legitimate user request. The ndnSIM module of ns3 is used for the corresponding simulation, and results of the simulation will be given to show the effectiveness of our algorithm. Copyright © 2014 John Wiley & Sons, Ltd.     

The effect of size of sub-sample on mineral analysis values of apple fruits

Apple fruits were divided into opposite sectors of different sizes, and the mineral analyses of the sectors were compared with whole fruit values. Opposite sectors as small 8-12% of whole fruit weight were found to be as representative as larger sectors. There was no evidence of either a constant or a proportional bias arising as a result of sub-sampling. Sub-sampling variation was greater for Ca than for N, P, K and Mg.     

Stress-Induced Grain Boundary Migration in Polycrystalline Copper

We use three-dimensional (3D) grain-continuum models to study grain boundary migration, treating each grain with anisotropic elastic properties. Grain boundary speeds are computed using a finite element method to calculate differences in strain energy density across grain boundaries. Body-fitted finite element meshes are used. An interface tracking program, PLENTE, is used to develop starting structures and move the grain boundaries based on these speeds. We demonstrate this procedure on textured films consisting of 〈100〉 and 〈111〉 fiber textured film. We also apply the model to a short section of a Cu line embedded in oxide. We conclude with a discussion on the relative impact of different driving forces for grain boundary motion.     

A report on HIPERLAN standardization

HIPERLAN is the new European standard for radio LANs currently being formulated by ETSI RES10 for operation at 5 GHz and 17 GHz. It will be suitable for radio replacement of wired LANs and for ad hoc networking providing a user data rate of 10–20 Mbit/s. This paper is a review of the work of ETSI RES10 on the formulation of the HIPERLAN standard. The origins of ETSI RES10 are documented. The targets set for HIPERLAN and the problems in achieving these targets are discussed. The paper reviews the technical arguments for and against the proposed solutions to these problems, concentrating on the design of the transmission scheme and the channel access mechanism. The discussions leading to significant decisions about the standard are summarized. If the FCC in the United States of America allocate the equivalent 5 GHz band to unlicensed wireless LAN systems, many of these discussions will be revisited for future standards in this band. The paper will be of interest to anyone in academia or industry wishing to be brought quickly up to date with the state of the standard in order to focus their research or development activities. The paper also gives a general insight into the technical side of the standards formulation process in ETSI.     

Noise reduction in rhythmic and multitrial biosignals with applications to event-related potentials

A new noise reduction algorithm is presented for signals displaying repeated patterns or multiple trials. Each pattern is stored in a matrix, forming a set of events, which is termed multievent signal. Each event is considered as an affine transform of a basic template signal that allows for time scaling and shifting. Wavelet transforms, decimated and undecimated, are applied to each event. Noise reduction on the set of coefficients of the transformed events is applied using either wavelet de- noising or principal component analysis (PCA) noise reduction methodologies. The method does not require any manual selection of coefficients. Nonstationary multievent synthetic signals are employed to demonstrate the performance of the method using normalized mean square error against classical wavelet and PCA based algorithms. The new method shows a significant improvement in low SNRs (typically <0 dB). On the experimental side, evoked potentials in a visual oddball paradigm are used. The reduced-noise visual oddball event-related potentials reveal gradual changes in morphology from trial to trial (especially for N1-P2 and N2-P3 waves at Fz), which can be hypothetically linked to attention or decision processes. The new noise reduction method is, thus, shown to be particularly suited for recovering single-event features in non- stationary low SNR multievent contexts.     

Three‐Dimensionally Ordered Macroporous Polymeric Materials by Colloidal Crystal Templating for Reversible CO2 Capture

The design and preparation of porous materials with controlled structures and functionalities is crucial to a variety of absorption‐ or separation‐relevant applications, including CO₂ capture. Here, novel functional polymeric materials with three‐dimensionally ordered macroporous (3DOM) structures are prepared by using colloidal crystals as templates using relatively simple, rapid, and inexpensive approaches. These ordered structures are used for the reversible CO₂ capture from ambient air by humidity swing. Typically, the colloidal crystal template is synthesized from polymer latex particles of poly(methyl methacrylate) (PMMA) or polystyrene (PS). To maintain the functionality of the material, it is important to prevent the porous structure collapsing, which can occur by the hydrolysis of the ester bonds in conventional crosslinkers under basic conditions. This hydrolysis can be prevented by using a water‐soluble crosslinker containing two quaternary ammonium moieties, which can be used to prepare stable porous crosslinked polymers with the monomer (vinylbenzyl)trimethylammonium chloride (VBTMACl) and using a PMMA‐based colloidal crystal template. The hydroxide‐containing monomer and dicationic crosslinker are synthesized from their chloride precursors, avoiding the ion‐exchange step which causes shrinkage of the pores. An analysis of different methods for infiltrating the monomer solution into the colloidal crystal template shows that infiltration using capillary forces leads to fewer defects than infiltration under a partial vacuum. In addition, functional macroporous films with micrometer thickness are prepared from a template of PS‐based colloidal crystals in a thin film. In general, the colloidal crystal templated materials showed improved CO₂ absorption/desorption rates and swing sizes compared to a commercially available material with similar functional groups. This work could easily be extended to create a new generation of ordered macroporous polymeric materials with tunable functionalities for other applications.     

Minimizing Average Schedule Length under Memory Constraints by Optimal Partitioning and Prefetching

Over the last 20 years, the performance gap between CPU and memory has been steadily increasing. As a result, a variety of techniques has been devised to hide that performance gap, from intermediate fast memories (caches) to various prefetching and memory management techniques for manipulating the data present in these caches. In this paper we propose a new memory management technique that takes advantage of access pattern information that is available at compile time by prefetching certain data elements before explicitly being requested by the CPU, as well as maintaining certain data in the local memory over a number of iterations. In order to better take advantage of the locality of reference present in loop structures, our technique also uses a new approach to memory by partitioning it and reducing execution to each partition, so that information is reused at much smaller time intervals than if execution followed the usual pattern. These combined approaches—using a new set of memory instructions as well as partitioning the memory—lead to improvements in total execution time of approximately 25% over existing methods.     

The muscle activation method: an approach to impedance control of brain-machine interfaces through a musculoskeletal model of the arm

Current demonstrations of brain-machine interfaces (BMIs) have shown the potential for controlling neuroprostheses under pure motion control. For interaction with objects, however, pure motion control lacks the information required for versatile manipulation. This paper investigates the idea of applying impedance control in a BMI system. An extraction algorithm incorporating a musculoskeletal arm model was developed for this purpose. The new algorithm, called the muscle activation method (MAM), was tested on cortical recordings from a behaving monkey. The MAM was found to predict motion parameters with as much accuracy as a linear filter. Furthermore, it successfully predicted limb interactions with novel force fields, which is a new and significant capability lacking in other algorithms.     

Streaming analysis in wireless sensor networks

Two new incremental models for online anomaly detection in data streams at nodes in wireless sensor networks are discussed. These models are incremental versions of a model that uses ellipsoids to detect first, second, and higher‐ordered anomalies in arrears. The incremental versions can also be used this way but have additional capabilities offered by processing data incrementally as they arrive in time. Specifically, they can detect anomalies ‘on‐the‐fly’ in near real time. They can also be used to track temporal changes in near real‐time because of sensor drift, cyclic variation, or seasonal changes. One of the new models has a mechanism that enables graceful degradation of inputs in the distant past (fading memory). Three real datasets from single sensors in deployed environmental monitoring networks are used to illustrate various facets of the new models. Examples compare the incremental version with the previous batch and dynamic models and show that the incremental versions can detect various types of dynamic anomalies in near real time. Copyright © 2012 John Wiley & Sons, Ltd.     

Enhanced Optical Properties and Opaline Self‐Assembly of PPV Encapsulated in Mesoporous Silica Spheres

A new poly(p‐phenylenevinylene) (PPV) composite material has been developed by the incorporation of insoluble PPV polymer chains in the pores of monodisperse mesoporous silica spheres through an ion‐exchange and in situ polymerization method. The polymer distribution within the resultant colloidal particles is characterized by electron microscopy, energy dispersive X‐ray microanalysis, powder X‐ray diffraction, and nitrogen adsorption. It was found that the polymer was selectively incorporated into the mesopores of the silica host and was well distributed throughout the body of the particles. This confinement of the polymer influences the optical properties of the composite; these were examined by UV–vis and fluorescence spectroscopy and time‐correlated single‐photon counting. The results show a material that exhibits an extremely high fluorescence quantum yield (approaching 85%), and an improved resistance to oxidative photobleaching compared to PPV. These enhanced optical properties are further complemented by the overall processability of the colloidal material. In marked contrast to the insolubility of PPV, the material can be processed as a stable colloidal dispersion, and the individual composite spheres can be self‐assembled into opaline films using the vertical deposition method. The bandgap of the opal can be engineered to overlap with the emission band of the polymer, which has significant ramifications for lasing.