Software reuse issues and perspectives

Software reuse could be implemented at several levels including the specification level, design level, program/subprogram library level, code level, and object-code level. However, reuse has a distinct definition for each of the above-mentioned levels. Moreover, the techniques applied to organize and manage reuse is different from one level to another. What's more, the complexity of the reuse methods and techniques increases as it moves from the specification level to the code and object-code levels. On the positive side, the time and space efficiency resulting from the application of reuse techniques improves in the same direction. Specification and design levels are at higher levels of abstraction than the other reuse levels, therefore their potential for accommodating reuse is greater and their adaptation to new applications can be simpler. However, the reuse process of the specification and design levels ultimately involves coding (be it system-generated or manual), testing, and debugging. On the other hand, reuse at code and object-code levels essentially eliminates coding and overall testing, hence it is more economical where a large collection of reusable software is organized in a software library     

Hardware/software cost analysis of interrupt processing strategies

A new study compares the architectural design and implementation costs of five strategies that let pipelined processors support precise interrupts. Hardware dominates the cost of all strategies except checkpoint repair, which, depending on the implementation, can incur either high software or hardware costs     

Self-healing ability and adhesion strength of capsule embedded coatings—Micro and nano sized capsules containing linseed oil

Urea–formaldehyde (UF) capsules were synthesized in micro and nano sizes, containing linseed oil (LO). The micro- and nanocapsules were incorporated through epoxy coatings and the coatings were applied on C-steel panels. Then the self-healing performance of the coatings was investigated. The corrosion resistance, adhesion strength and its retaining after immersion of nanocapsule incorporated coatings were compared with the optimum microcapsule incorporated ones.     

Tung oil: An autonomous repairing agent for self-healing epoxy coatings

The capability of the encapsulated Tung oil was investigated as a scratch healing agent for self-healing coatings. Encapsulation of Tung oil with urea–formaldehyde shell was carried out by in situ polymerization. Before the mechanical agitation of microcapsules into epoxy resin, their characteristics were evaluated by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Released Tung oil from ruptured microcapsules healed the artificial scratch in the coating matrix successfully. Corrosion resistance of healed area was evaluated by electrochemical impedance spectroscopy (EIS) and immersion test; and the results were compared with neat epoxy coating.     

Energy-efficient and secure in-network storage and retrieval for WSNs: an adaptive approach

Storage and retrieval of data in Wireless Sensor Networks (WSNs) have been found to be challenging issues in recent studies. The two principal approaches used in almost all proposed schemes in this field are Centralized and Decentralized. Many investigations have considered the security and communication issues in centralized schemes where a central node exists as the sink and all collected data are sent to it to be processed or the central node provides access to the possible users. In decentralized systems, all nodes are equally responsible for the duties of the central node in centralized approaches. In cases where sensors cannot transmit data immediately, which is usually the case in distributed approaches, in-network storage and retrieval is an alternative with its own security and communication issues stemming from the properties of energy sensitive sensors. In this paper, a semi-centralized scheme is introduced that is based on a number of traditional techniques, namely, clustering, symmetric and asymmetric key-management, and threshold secret sharing. The proposed scheme provides an energy-efficient and secure in-network storage and retrieval that could be applied to WSNs. A predictive method is proposed to adaptively determine the proper parameters for the threshold secret sharing technique. Confidentiality, dependability, and integrity of the sensed data are enhanced in a distributed manner with fairly low communication and computation costs. Simulations were utilized to illustrate the effect of several network parameters on energy consumption and to come up with optimization recommendations for the parameters of the proposed secret sharing scheme.     

Age-based anonymity: a randomized routing approach to communication unobservability

Providing anonymous communication on networks of interconnected computers is an active area of research which aims to enhance the privacy of the users of such networks. Communication unobservability, stronger property compared to anonymity, attempts to guarantee that legitimate messages are not discernible from dummy traffic. A network with an active global adversary is one which it is assumed that all nodes in the network are potentially being monitored at all times, and also that at any time any node could be an adversary. This paper introduces a set of anonymous system design requirements for providing enhanced communication unobservability. A new anonymous networking system was designed based on these requirements to provide both sender and receiver anonymity. The proposed system has a structured peer-to-peer network architecture and a randomized routing algorithm to obfuscate the detection of communication paths and the message routing patterns. An age-based method is proposed to prevent even the first node after the sender from identifying the original sender. A simulation program was designed and implemented to test the proposed system. The effect of different parameters on the proposed algorithm is demonstrated using a simulation program.     

A review on self-healing coatings based on micro/nanocapsules

Polymer coating systems are classically applied on a metal surface to provide a dense barrier against the corrosive species. Coatings are susceptible to damage in the form of cracks, which form deep within the structure where detection is difficult and repair is almost impossible. Major advances for automatic repairing of defects have been made in the present decade within the field of self-healing polymeric materials. One of the most significant types of smart coatings is self-healing coating, which has the ability to release encapsulated active agents in a controlled way. They can be employed to develop a new family of smart multifunctional coatings. Incorporating micro/nanocapsules in coating matrix provides release of repairing agent rapidly after triggering due to crack propagation in coatings and gifts the self-healing to the coatings. This review covers the effective parameters in synthesis of micro/nanocapsules, several approaches to fabricate self-healing coatings based on these capsules and disadvantages of embedding them in coatings matrix. Current comprehensive review also provides all the knowledge of self-healing coatings based on micro/nanocapsules to whom that are concerned with coatings and corrosion prevention.     

Multi-objective design optimization of composite laminates using discrete shuffled frog leaping algorithm

This paper deals with the optimization of composite laminates using discrete shuffled frog leaping method. This approach is used to find optimal values of three design variables including fiber orientations in matrices, thickness of each ply and number of layers in order to minimize the weights and costs of the laminates under various loading cases. Three well-known failure criteria are employed to investigate the capability of the plate in bearing the applied loads. Moreover, the comparison of the obtained results with previously reported results is performed to prove the applicability of the algorithm in optimizing composite materials.