Biblio

This paper presents a proximity coupled wideband wearable antenna operating between 4.71 GHz and 5.81 GHz with 5.2 GHz as centre frequency for biomedical telemetry applications in ISM band (IEEE 802.11 Standard). Two layers of different flexible substrate materials, ethylene-vinyl acetate and felt make the design mechanically stable. Bandwidth improvement is achieved by introducing two slots on elliptical ground plane. Highest gain of 3.72 dB and front to back ratio (FBR) of 6.55 is obtained in the given frequency band. The dimensions of antenna have been optimized to have desired bandwidth of 1100 MHz (\$\textbackslashtextbackslashsimeq\$21%). The specific absorption rate (SAR) value is 1.12 \$W/Kg\$ for 1 g of human body tissue. Both simulated and measured results are presented for the structure.

The fingerprint sensor based on pMUTs was reported [1]. Spatial resolution of the image depends on the size of the acoustic source when a plane wave is used. If the size of the acoustic source is smaller, piezoelectric films with high dielectric constant are required. In this study, in order to obtain small acoustic source, we proposed Pb(Zrx Th-x)O3 (PZT) epitaxial transducers with high dielectric constant. PbTiO3 (PTO) epitaxial films were grown on conductive La-SrTiO3 (STO) substrate by RF magnetron sputtering. Longitudinal wave conversion loss of PTO transducers was measured by a network analyzer. The thermoplastic elastomer was used instead of real fingerprint. We confirmed that conversion loss of piezoelectric film/substrate structure was increased by contacting the elastomer due the change of reflection coefficient of the substrate bottom/elastomer interface. Minimum conversion loss images were obtained by mechanically scanning the soft probe on the transducer surface. We achieved the detection of the fingerprint phantom based on the elastomer in the GHz.

Network Function Virtualization (NFV) is a recent concept where virtualization enables the shift from network functions (e.g., routers, switches, load-balancers, proxies) on specialized hardware appliances to software images running on all-purpose, high-volume servers. The resource allocation problem in the NFV environment has received considerable attention in the past years. However, little attention was paid to the security aspects of the problem in spite of the increasing number of vulnerabilities faced by cloud-based applications. Securing the services is an urgent need to completely benefit from the advantages offered by NFV. In this paper, we show how a network service request, composed of a set of service function chains (SFC) should be modified and enriched to take into consideration the security requirements of the supported service. We examine the well-known security best practices and propose a two-step algorithm that extends the initial SFC requests to a more complex chaining model that includes the security requirements of the service.

One of the key aspects of IoT-based systems, which we believe has not been getting the attention it deserves, is provenance. Provenance refers to those actions that record the usage of data in the system, along with the rationale for said usage. Historically, most provenance methods in distributed systems have been tightly coupled with those of the underlying data processing frameworks in such systems. However, in this paper, we argue that IoT provenance requires a different treatment, given the heterogeneity and dynamism of IoT-based systems. In particular, provenance in IoT-based systems should be decoupled as far as possible from the underlying data processing substrates in IoT-based systems.To that end, in this paper, we present Genoma, our ongoing work on a system for provenance-as-a-service in IoT-based systems. By "provenance-as-a-service" we mean the following: distributed provenance across IoT devices, edge and cloud; and agnostic of the underlying data processing substrate. Genoma comprises a set of services that act together to provide useful provenance information to users across the system. We also show how we are realizing Genoma via an implementation prototype built on Apache Atlas and Tinkergraph, through which we are investigating several key research issues in distributed IoT provenance.

Back-end-of-line compatible integration of NdFeB-based micro magnets onto 8 inch Si substrates is presented. Substrate conditioning procedures to enable further processing in a cleanroom environment are discussed. It is shown that permanent magnetic structures with lateral dimensions between 25μm and 2000μm and a depth up to 500μm can be fabricated reliably and reproducibly with a remanent magnetization of 340mT at a standard deviation as low as 5% over the substrate. To illustrate post-processing capabilities, the fabrication of micro magnet arrangements embedded in silicon frames is described.

Surface acoustic wave (SAW) optical sensor based on two-dimensional (2D) sensing layer can always provide extremely high sensitivity. As an attractive option, the application of exfoliated 2D perovskite on acousto-optic coupling optical sensor is investigated. In this work, exfoliated 2D (PEA)2PbI4 sheet was transferred as a sensing layer onto the delay area of a dual-port SAW resonator with resonant frequency 497 MHz. From the response under 532 nm laser with intensity of 0.9 mW/cm2, a largest frequency shift of 13.92 MHz was observed. The ultrahigh sensitivity up to 31.6 ppm/(μW/cm2) was calculated by experiment results. We also carried out theoretical analysis and finite element simulation of 3D model to demonstrate the mechanism and validity for optical sensing. The fabricated optical sensor expressed great potential for a variety of optical applications.

Alternatives to rare earth permanent magnets, such as alnico, will reduce supply instability, increase sustainability, and could decrease the cost of permanent magnets, especially for high-temperature applications, such as traction drive motors. Alnico magnets with moderate coercivity, high remanence, and relatively high-energy product are conventionally processed by directional solidification and (significant) final machining, contributing to increased costs and additional material waste. Additive manufacturing (AM) is developing as a cost effective method to build net-shape 3-D parts with minimal final machining and properties comparable to wrought parts. This paper describes initial studies of net-shape fabrication of alnico magnets by AM using a laser engineered net shaping (LENS) system. High-pressure gas atomized pre-alloyed powders of two different modified alnico “8” compositions, with high purity and sphericity, were built into cylinders using the LENS process, and followed by heat treatment. The magnetic properties showed improvement over their cast and sintered counterparts. The resulting alnico permanent magnets were characterized using scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and hysteresisgraph measurements. These results display the potential for net-shape processing of alnico permanent magnets for use in next generation traction-drive motors and other applications requiring high temperatures and/or complex engineered part geometries.

The development of radar technology, Synthetic Aperture Radar (SAR) and Unmanned Aerial Vehicle (UAV) requires the communication facilities and infrastructures that have variety of platforms and high quality of image. In this paper, we obtain the basic configuration of triangle array antenna using corporate feeding-line for Circularly Polarized- Synthetic Aperture Radar (CP-SAR) sensor embedded on small UAV or drone airspace with compact, small, and simple configuration. The Method of Moments (MoM) is chosen in the numerical analysis for fast calculation of the unknown current on the patch antenna. The developing of triangle array antenna is consist of four patches of simple equilateral triangle patch with adding truncated corner of each patch and resonant frequency at f = 1.25 GHz. Proximity couple, perturbation segment, single feeding method are applied to generate the circular polarization wave from radiating patch. The corporate feeding-line design is implemented by combining some T-junctions to distribute the current from input port to radiating patch and to reach 2×2 patches. The performance results of this antenna, especially for gain and axial ratio (Ar) at the resonant frequency are 11.02 dBic and 2.47 dB, respectively. Furthermore, the two-beams appeared at boresight in elevation plane have similar values each other i.e. for average beamwidth of 10 dBic-gain and the 3 dB-Ar are about 20° and 70°, respectively.

The growing computerization of critical infrastructure as well as the pervasiveness of computing in everyday life has led to increased interest in secure application development. We observe a flurry of new security technologies like ARM TrustZone and Intel SGX, but a lack of a corresponding architectural vision. We are convinced that point solutions are not sufficient to address the overall challenge of secure system design. In this paper, we outline our take on a trusted component ecosystem of small individual building blocks with strong isolation. In our view, applications should no longer be designed as massive stacks of vertically layered frameworks, but instead as horizontal aggregates of mutually isolated components that collaborate across machine boundaries to provide a service. Lateral thinking is needed to make secure systems going forward.

Network virtualization sits firmly on the Internet evolutionary path allowing researchers to experiment with novel clean-slate designs over the production network and practitioners to manage multi-tenants infrastructures in a flexible and scalable manner. In such scenarios, isolation between virtual networks is often intended as purely logical: this is the case of address space isolation or flow space isolation. This approach neglects the effect that network virtualization has on resource allocation network-wide. In this work we investigate the price paid by a purely logical approach in terms of performance degradation. This performance loss is paid by the actual users of a multi-tenants datacenter network. We propose a solution to this problem leveraging on a new network virtualization primitive, namely an online link utilization feedback mechanism. It provides each tenant with the necessary information to make efficient use of network resources. We evaluate our solution trough a real implementation exploiting the OpenFlow protocol. Empirical results confirm that the proposed scheme is able to support tenants in exploiting virtualized network resources effectively.
 

It is expected that clean-slate network designs will be implemented for wide-area network applications. Multi-tenancy in OpenFlow networks is an effective method to supporting a clean-slate network design, because the cost-effectiveness is improved by the sharing of substrate networks. To guarantee the programmability of OpenFlow for tenants, a complete flow space (i.e., header values of the data packets) virtualization is necessary. Wide-area substrate networks typically have multiple administrators. We therefore need to implement a flow space virtualization over multiple administration networks. In existing techniques, a third party is solely responsible for managing the mapping of header values for flow space virtualization for substrate network administrators and tenants, despite the severity of a third party failure. In this paper, we propose an AutoVFlow mechanism that allows flow space virtualization in a wide-area networks without the need for a third party. Substrate network administrators implement a flow space virtualization autonomously. They are responsible for virtualizing a flow space involving switches in their own substrate networks. Using a prototype of AutoVFlow, we measured the virtualization overhead, the results of which show a negligible amount of overhead.