Abstract The design of a secure communication scheme for Radio Frequency Identification (RFID) systems has been extensively studied in recent years in view of the awareness of individual privacy and the requirement of robust system security. Most of previous works assume the communication channel between an RFID reader and its backend server is secure and concentrate on the security enhancement between... The design of a secure communication scheme for Radio Frequency Identification (RFID) systems has been extensively studied in recent years in view of the awareness of individual privacy and the requirement of robust system security. Most of previous works assume the communication channel between an RFID reader and its backend server is secure and concentrate on the security enhancement between an RFID tag and an RFID reader. However, once RFID reader modules are extensively deployed in consumer’s handheld devices, the security violation problems at reader side will be deeply concerned by individuals and organizations. In this paper, it is assumed that the future communication environment for RFID systems will be all wireless and insecure. Under such infrastructure, handheld device such as mobile phone, embedded with RFID reader modules will be situated everywhere and operated with many RFID tags in various RFID application systems. Hence in this paper, an authentication protocol in mobile RFID environment is proposed which effectively achieves forward security with preventing replay, eavesdropping, and counterfeit tag attacks. Based on the security analyses, it has been shown that the scheme can enhance data security and provide privacy protection at reader side even in the presence of an active adversary under insecure mobile RFID environment. Read More Read Less

Abstract Object-oriented design is becoming very popular in today’s software development. An object-oriented information system is decomposed into subjects, each subject is decomposed into classes of objects. Good object-oriented system design should exhibit high cohesion inside subjects and low coupling among subjects. Yet, few quantitative studies of the actual use of cohesion and coupling have been conducted at the system level.... Object-oriented design is becoming very popular in today’s software development. An object-oriented information system is decomposed into subjects, each subject is decomposed into classes of objects. Good object-oriented system design should exhibit high cohesion inside subjects and low coupling among subjects. Yet, few quantitative studies of the actual use of cohesion and coupling have been conducted at the system level. These two concepts are defined qualitatively, and only at the class level, not at the system level. In this work, metrics are introduced for cohesion and coupling and used to define a quality metric at the system level. The feasibility of the approach is demonstrated by an example using a real information system. Read More Read Less

Abstract A scanning-beam antenna on metamaterial coplanar structures is presented. The proposed antenna is, in essence, a composite of Right/Left-Handed (CRLH) coplanar waveguide (CPW) structure incorporating distributed periodic structures with L-C high-pass filter topology which support left-handed (LH) waves. The negative refractive index (NRI) properties of these structures are shown theoretically, numerically and validated by full-wave simulations. The supported LH wave... A scanning-beam antenna on metamaterial coplanar structures is presented. The proposed antenna is, in essence, a composite of Right/Left-Handed (CRLH) coplanar waveguide (CPW) structure incorporating distributed periodic structures with L-C high-pass filter topology which support left-handed (LH) waves. The negative refractive index (NRI) properties of these structures are shown theoretically, numerically and validated by full-wave simulations. The supported LH wave is fully characterized and based on the composite right/left-handed transmission-line (CRLH-TL) theory; and the dispersion characteristics, refractive indexes and Bloch impedance are derived theoretically. In addition, formulas to extract equivalent-circuit parameters from full-wave simulation are given. Since the distance d between adjacent cells of the array is small, d << λo and the array becomes a uniform leaky-wave antenna (LWA) for a 10-cell operating near 10 GHz. Simulated radiation pattern, gain, and associated loss budget are presented. The results of LWA exhibit scanning-beam capability from backfire-to-endfire direction and accord well with the theoretical analysis. The antenna is printed on thin and flexible substrate (h = 25 μm). Furthermore, since the antenna is implemented with low-cost and CPW technology, it is a good candidate for integrated RF/microwave systems that can be used in digital wireless communications and radars. Read More Read Less

Abstract This paper presents a new approach of modelling, design, and characteristics of variable radio frequency microelectromechanical system (RF-MEMS) capacitor integrated on leaky wave antenna (LWA) operating at 94 GHz. This antenna was implemented on grounded coplanar waveguide (CPW). A 2D distributed mathematical model for the capacitor has been developed along this paper; we formulate and solve the static and dynamic... This paper presents a new approach of modelling, design, and characteristics of variable radio frequency microelectromechanical system (RF-MEMS) capacitor integrated on leaky wave antenna (LWA) operating at 94 GHz. This antenna was implemented on grounded coplanar waveguide (CPW). A 2D distributed mathematical model for the capacitor has been developed along this paper; we formulate and solve the static and dynamic problems associated with the proposed RF-MEMS capacitor. The obtained results are in good agreement with the ANSYS simulations. A full-wave simulation was used to investigate the microwave performances of the proposed antenna. This prototype exhibits continuous tuning radiation angle and beamwidth capability by tuning bias voltages from 0 V to 60 V. The proposed antenna presents flexibility, high directivity, compact size, and low-cost characteristics. The LWA can be used in applications which require high-performance such as imaging arrays and collision-avoidance radars. Read More Read Less

Abstract Users of distributed systems often detect performance problems of different types and sources which can sometimes be difficult to trace down to a specific cause due to the complex structure of distributed systems. However, determining the source of the performance problem is highly critical in finding an efficient solution. Managing data fragments on different nodes is one of the major... Users of distributed systems often detect performance problems of different types and sources which can sometimes be difficult to trace down to a specific cause due to the complex structure of distributed systems. However, determining the source of the performance problem is highly critical in finding an efficient solution. Managing data fragments on different nodes is one of the major sources of such a problem and is considered as a big challenge facing system developers and designers in a distributed environment. This paper contributes in deciding on the most efficient possible allocation alternatives for data partitions in a distributed environment based on the access patterns and the cost data manipulation. Read More Read Less

Abstract In biosciences, data mining is concerned with processing large amount of data which is characterized by heterogeneity, ever changing and spread in different complex environments. Resource discovery from massive data poses a formidable task for many newer as well as routine applications. The issues addressed in the massive data environments so far are the heterogeneity issues and the semantic focus... In biosciences, data mining is concerned with processing large amount of data which is characterized by heterogeneity, ever changing and spread in different complex environments. Resource discovery from massive data poses a formidable task for many newer as well as routine applications. The issues addressed in the massive data environments so far are the heterogeneity issues and the semantic focus is less. In the current work, we deal with the resource discovery in large-scale environments (as data grid systems) considering data semantic heterogeneity of biomedical sources. There are many benefits such as-(i) allowing a permanent access, through an addressing system, from any domain ontology DOi to another DOj (inter-domain discovery) despite peers’ dynamicity, (ii) reducing the maintenance cost and (iii) taking into account the semantic heterogeneity. Read More Read Less