Optimal security limits of RFID distance bounding protocols

In this paper, we classify the RFID distance bounding protocols having bitwise fast phases and no final signature. We also give the theoretical security bounds for two specific classes, leaving the security bounds for the general case as an open problem. As for the classification, we introduce the notion of k-previous challenge dependent (k-PCD) protocols where each response bit depends on the current and k-previous challenges and there is no final signature. We treat the case k = 0, which means each response bit depends only on the current challenge, as a special case and define such protocols as current challenge dependent (CCD) protocols. In general, we construct a trade-off curve between the security levels of mafia and distance frauds by introducing two generic attack algorithms. This leads to the conclusion that CCD protocols cannot attain the ideal security against distance fraud, i.e. 1/2, for each challenge-response bit, without totally losing the security against mafia fraud. We extend the generic attacks to 1-PCD protocols and obtain a trade-off curve for 1-PCD protocols pointing out that 1-PCD protocols can provide better security than CCD protocols. Thereby, we propose a natural extension of a CCD protocol to a 1-PCD protocol in order to improve its security. As a study case, we give two natural extensions of Hancke and Kuhn protocol to show how to enhance the security against either mafia fraud or distance fraud without extra cost

Dual Frequency Microwave Resonator for Non-invasive detection of Aqueous Glucose

A novel dual-band microwave sensor for noninvasive detection of glucose concentration is presented. The proposed sensor consists of an open-loop resonator coupled to the input and the output of the structure. The resonator is loaded with modified split-ring resonators (SRRs) for dual-band operation as a sensing area. The open-loop resonator with electric coupling operating at low band functions as a host. The SRRs embedded into the open-loop resonator operate at a high band. In the proposed sensor, the overall size is miniaturized using the embedded resonator structure. This configuration has two transmission poles (TPs) and one transmission zero (TZ) in transmission coefficients, which are all sensitive to glucose-level (GL) variation. A dielectric container made with 3-D printer is used for dropping the aqueous glucose samples on the sensing section of the sensor. The experimental results obtained from the prototype having a dielectric container shows two resonance frequencies at 1.8 and 2.67 GHz as well as a TZ at 2.32 GHz. A glucose solution with deionized water in the range from 89 to 456 mg/dL is used in the measurements. For this range of glucose concentrations, the experimental frequency resolutions are 0.78 and 0.95 MHz/(mg/dL) based on the TP and the TZ, respectively.</p

T-Junction Loaded with Interdigital Capacitor for Differential Measurement of Permittivity

The microwave sensors have been successfully used for permittivity measurement. These sensors suffer from limited sensitivity and environmental effects. This article presents a novel T-junction highly sensitive microwave sensor for permittivity measurement of low-loss solid materials. The proposed sensor operation principle is based on downshifting the transmission zero (TZ) of the outputs of T-junction with the coupling of the material under test (MUT). The sensing section consists of an interdigital capacitor (IDC) located in between the lines of the T-junction. IDC is directly connected to output arms of T-junction, so that it could disturb the outputs strongly. Any change in electric field concentration in IDC directly is transmitted to the outputs and is translated as TZ change. Design steps including T-junction and IDC effects on outputs are presented in detail. The sensor operation principle is described through an equivalent circuit model, which is validated by simulation and experimental results. Two outputs of the proposed sensor show the same electrical performances, which allow differential operation mode. Hence, cross sensitivity due to environmental factors can be tolerated by the sensor. Measurement results of the fabricated prototype show 112-MHz frequency shift per unit permittivity change and a normalized sensitivity of 3.9%, which are larger than available similar sensors. The proposed sensor is implemented on a 22.22 × 18.76 × 1.6 mm3 printed circuit board.</p

An Innovative Structural Solution to Failed Stabilized Earth Embankment in Multilevel Interchange

This paper summarizes a case study of a failure in a mechanically stabilized earth retaining wall ramp heading to a multilevel interchange. The failure was caused by a washout cavity resulting from a long-term leakage from unknown existing wet utilities adjacent to the mechanically stabilized earth retaining wall. The interchange is located within a very congested traffic area and has limited right of way and working space. The methodology of investigation, root cause of the failure, evaluation of the existing structure and innovative solution to the problem within fast-track design and construction are studied in this paper. Due to the necessity of maintaining the existing traffic movements at the interchange which is located at one of the most important expressway routes, timely rectification methodology was conceived, designed and implemented. This paper is prepared only to evaluate the technical innovative alternatives, solutions and fast-track construction without mentioning the interchange and project area

Unique Structural Design and Construction Challenges for Al Bustan South Project in Qatar

The Al Bustan Street South (ABS) Expressway Project features the longest dual carriageway bridges in Qatar spanning 2.6 km each, with a minimum of four lanes in each direction from south of Al Waab Street to south of Rayyan Road. These twin mainline bridges carry the ABS Expressway forming a three-level interchange at Al Waab Street and two-level crossings at Al Rasheeda Street and Snay Bu Hasa. The Al Waab Interchange consists of multiple structures; namely, the mainline bridges at Level +1, the West-South directional ramp at Level +2, and the East-North directional ramp at Level +2. In addition, there are six other on/off ramp structures that tie into the mainline bridges at various locations. While the current construction maintains Al Waab Street at Level 0, in its ultimate configuration, Al Waab Street will contain an underpass at Level -1, resulting in Level +4 interchange. This underpass due to its proximity to the bridge supports requires unique design considering future constructability. The ABS Expressway is part of the prestigious Sabah Al Ahmad Corridor which once constructed will provide a separate north to south route from the Landmark Mall to Hamad International Airport. The appearance of the bridges along the Sabah Al Ahmad Corridor will contain aesthetically pleasing cladding attached to the parapets with artificial green walls running down select piers and MSE Walls. This paper summarizes recent developments in the design and build for the future underpass, which requires special attention in the bridge design while also considering aesthetic features

Key Lessons Learnt from Stakeholder Management in Design and Build Projects in Qatar

Stakeholders in the construction industry require accurate, reliable and timely information in order to streamline the design and construction of Projects. Design Bid Build or Design and Build contracts need a process for seeking the latest requirements, interests and existing assets of all the stakeholders involved. This to lead and guide the projects to deliver in a timely, cost-effective and safe manner. This paper summarizes the multi-discipline Stakeholder management challenges and their proactive approach during the execution of the Expressway Programme by Public Works Authority, Qatar illustrated by a case study and actual actions from the industry. Various internal surveys have been undertaken to assess the issues to be resolved. Key to managing the time and cost impacts on the construction projects are identifying the needs of stakeholders, stakeholder communication procedures, their requirements, identification of existing assets, expected future requirements and decisions among the stakeholder. Unique and innovation construction procedures are highlighted in order to overcome construction challenges

The effect of perforations on the stress wave propagation characteristics of multilayered materials

The effect of perforated interlayers on the stress wave transmission of multilayered materials was investigated both experimentally and numerically using the Split Hopkinson pressure bar (SHPB) testing. The multilayer combinations consisted of a ceramic face plate and a glass/epoxy backing plate with a laterally constrained low modulus solid or perforated rubber and Teflon interlayer. The perforations on rubber interlayer delayed the stress rise time and reduced the magnitude of the transmitted stress wave at low strains, while the perforations allowed the passage of relatively high transmitted stresses at large strains similar to the solid rubber interlayer. It was concluded that the effect of perforations were somewhat less pronounced in Teflon interlayer configuration, arising from its relatively low Poisson's ratio. It was finally shown that SHPB testing accompanied with the numerical simulations can be used to analyze the effect of compliant interlayer insertion in the multilayered structures. © The Author(s) 2015

Determination of scattering center of multipath signals using geometric optics and Fresnel zone concepts

AbstractIn this study, a method for determining scattering center (or center of scattering points) of a multipath is proposed, provided that the direction of arrival of the multipath is known by the receiver. The method is based on classical electromagnetic wave principles in order to determine scattering center over irregular terrain. Geometrical optics (GO) along with Fresnel zone concept is employed, as the receiver, the transmitter positions and irregular terrain data are assumed to be provided. The proposed method could be used at UHF bands, especially, operations of radars and electronic warfare applications