Chemical toughening of epoxies. I. Structural modification of epoxy resins by reaction with hydroxy-terminated poly(butadiene-co-acrylonitrile)

In an attempt to toughen the epoxy resin matrix for fiber-reinforced composite applications, a chemical modification procedure of a commercially available bisphenol-A-based epoxy resin using reactive liquid rubber HTBN [hydroxy-terminated poly(butadiene-co-acrylonitrile)] and TDI (tolylene diisocyanate) is described. The progress of the reaction and the structural changes during modification process are studied using IR spectroscopy, viscosity data, and chemical analysis (epoxy value determination). The studies support the proposition that TDI acts as a coupling agent between the epoxy and HTBN, forming a urethane linkage with the former and an oxazolidone ring with the latter. The chemical reactions that possibly take place during the modification are discussed.     

Short‐beam three‐point bend test study in syntactic foam. Part III: Effects of interface modification on strength and fractographic features

Syntactic foam slabs having uncoated microballoons and paraffin oil surface‐treated microballoons were fabricated and tested for short‐beam three‐point bend test. The work points to the role of paraffin oil coating first weakening the interface between the microballoons and the matrix and hence lowering the efficiency of load transfer from matrix to the fillers (i.e., microballoons). This led to an overall decrement of 71% in the experimentally measured strength value compared to the deduced value for uncoated microballoons' specimens. The large strengths for uncoated microballoons specimens can be traced to the presence of the curvilinear marks in the matrix that, incidentally, are absent in the case of paraffin oil coated specimens. These observations are revealed distinctly in the microscopy of test‐failed specimens. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 687–693, 2005     

Mullitization of Diphasic Aluminosilicate Gels

Recent studies have shown that the mullitization of diphasic aluminosilicate matrices comprising transitional alumina and amorphous silica occurs via a nucleation and growth process. Nucleation is preceded by a temperature-dependent incubation period. Following this incubation period, rapid nucleation of mullite occurs, producing about 1.8 × 10¹¹ nuclei/cm³, which remains constant throughout the rest of the transformation. Both incubation and mullite growth are thermally activated processes with apparent activation energies of 987 ± 63 and 1070 ± 200 kJ/mol, respectively. The growth rate of mullite grains under isothermal conditions is time dependent. An interpretation of these results is proposed on the basis of the nucleation and growth concepts of LaMer and Dinegar which supports the concept that the growth rate of mullite grains is controlled by the dissolution of transitional alumina into the amorphous matrix.     

Short beam three point bend tests in syntactic foams. Part I: Microscopic characterization of the failure zones

Scanning Electron Microscopic (SEM) studies were carried out on the failure surface of syntactic foam material tested in a short beam three point bend test (SBT) by employing 21 × 15 × 3 mm³ dimension bearing specimens. The syntactic foams were fabricated using glass microballoons in epoxy binder. The failure of the tensile, compression, and shear dominated regions were studied by SEM at different magnifications. The tensile region had characteristic features, such as partial debonding of the microballoons from the matrix and cracking of glass microballoons, apart from matrix cracking and some river pattern features. The compression side was characterized by crushing and collapsing of microballoons, resulting in accumulation of debris with no apparent river pattern for matrix‐rich regions. The midway positions of the SBT failed surface comprised of deformation bands in the matrix and occasional debonding of microballoons. The morphology recorded in the tensile and compression regions corroborated well with the results obtained on these foam samples in those specimens that were subjected to pure uniaxial tension and compression, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 673–679, 2005     

A Physarum-inspired approach to supply chain network design基于多头绒泡菌模型的供应链网络设计算法

A supply chain is a system which moves products from a supplier to customers, which plays a very important role in all economic activities. This paper proposes a novel algorithm for a supply chain network design inspired by biological principles of nutrients’ distribution in protoplasmic networks of slime mould Physarum polycephalum. The algorithm handles supply networks where capacity investments and product flows are decision variables, and the networks are required to satisfy product demands. Two features of the slime mould are adopted in our algorithm. The first is the continuity of flux during the iterative process, which is used in real-time updating of the costs associated with the supply links. The second feature is adaptivity. The supply chain can converge to an equilibrium state when costs are changed. Numerical examples are provided to illustrate the practicality and flexibility of the proposed method algorithm.     

Design of high-speed data transfer turbo code for body channel communication transceivers

In this work, a digital differential transmitter based on low-power wireless compensation transceiver for body channel communication (BCC) is proposed. Further, the proposed transceiver is composed of Touch Status Detection Unit (TSDU), Wireless Status Compensation Unit (WSCU), and a reconfigurable preamplifier. Initially, the human body channel environment for wireless communication is investigated based on properties from 1 to 100 MHz. Further, the turbo code-based encoding scheme is used to encode the data before transferring the data on the transmitter side. Also, the proposed error-correcting parallel turbo decoder using a modified step-by-step algorithm is presented. The turbo code-based decoding scheme is used to recover the error-free transmitted data at the receiver side. Results demonstrate that the proposed BCC transceiver is designed using 90 nm CMOS technology and it is observed that the proposed BCC transceiver has utilized an area of 600mm². Also, the maximum data rate achieved by a proposed BCC transceiver was 100 Mbps, and the overall transceiver power consumption is 0.42 mW, and energy for communication is 0.02 nj/b.     

A post quantum secure construction of an authentication protocol for satellite communication

Satellite's communication system is used to communicate under significant distance and circumstances where the other communication systems are not comfortable. Since all the data are exchanged over a public channel, so the security of the data is an essential component for the communicating parties. Both key exchange and authentication are two cryptographic tools to establish a secure communication between two parties. Currently, various kinds of authentication protocols are available to establish a secure network, but all of them depend on number–theoretical (discrete logarithm problem/factorization assumption) hard assumptions. Due to Shor's and Grover's computing algorithm number theoretic assumptions are breakable by quantum computers. Although Kumar and Garg have proposed a quantum attack-resistant protocol for satellite communication, it cannot resist stolen smart card attack. We have analyzed that how Kumar and Garg is vulnerable to the stolen smart card attack using differential power analysis attack described in He et al and Chen and Chen. We have also analyzed the modified version of signal leakage attack and sometimes called improved signal leakage attack on Kumar and Garg's protocol. We have tried to construct a secure and efficient authentication protocol for satellites communication that is secure against quantum computing. This is more efficient as it requires only three messages of exchange. This paper includes security proof and performance of the proposed authentication and key agreement protocol.     

Process diagnostics using trace alignment: Opportunities, issues, and challenges

Business processes leave trails in a variety of data sources (e.g., audit trails, databases, and transaction logs). Hence, every process instance can be described by a trace, i.e., a sequence of events. Process mining techniques are able to extract knowledge from such traces and provide a welcome extension to the repertoire of business process analysis techniques. Recently, process mining techniques have been adopted in various commercial BPM systems (e.g., BPM|one, Futura Reflect, ARIS PPM, Fujitsu Interstage, Businesscape, Iontas PDF, and QPR PA). Unfortunately, traditional process discovery algorithms have problems dealing with less structured processes. The resulting models are difficult to comprehend or even misleading. Therefore, we propose a new approach based on trace alignment. The goal is to align traces in such a way that event logs can be explored easily. Trace alignment can be used to explore the process in the early stages of analysis and to answer specific questions in later stages of analysis. Hence, it complements existing process mining techniques focusing on discovery and conformance checking. The proposed techniques have been implemented as plugins in the ProM framework. We report the results of trace alignment on one synthetic and two real-life event logs, and show that trace alignment has significant promise in process diagnostic efforts.     

An Indo-Soviet experiment on anmhd generator test section at the Soviet U-02 facility

This paper summarizes the major results of the joint Indo-Soviet experiment for testing the Indianmhd generator channel section, designed and fabricated at the Bhabha Atomic Research Centre, Bombay, which was carried out at the U-02 facility in Moscow, USSR, in May 1980. The total test duration was 65 hours and included electrophysical tests and life tests under applied electric fields. The main purpose of the tests was to substantiate the physical concepts, computer codes, design features and special processing techniques involved in the development ofmhd generators for the Indian pilot plant at Tiruchirapalli. The experimental observations on the phenomena of heat transfer to the walls, gas dynamics in the channel, electrical characteristics of the generator and near-electrode processes including the analysis of arc spots correlate with the theoretical estimates based on present understanding of the physical processes occuring in similarmhd generators. The post-operational inspection of the channel section and extensive investigation of materials through microscopic analysis, chemical analysis and x-ray analysis are also reported in this paper. The joint test programme has clearly demonstrated the definite operating capability of the test section and has given sufficient information and encouragement for building better and improved channels for the future.     

Understanding sources of user variability in computer-based data entry performance

The pervasive use of computers in work settings implies that an increased number of workers, with varying levels of skills and abilities, will be performing computerbased tasks. This study investigated the impact of age, cognitive abilities, and computer experience on the performance of a real world data entry task. One hundred and ten subjects, ranging in age from 20 - 75 years, performed the task for nine hours following task training. The results indicated that abilities such as visuo-spatial skills, motor skills and processing speed had a significant impact on performance as did age and prior computer experience. With respect to age, the older participants completed less work than the younger and middle-aged subjects. Age differences in psychomotor skills and processing speed appeared to be important factors underlying age effects. In fact, the data indicated that after controlling for differences in these abilities age was no longer a significant predictor of work output. Further, after controlling for differences in work output the older people made fewer errors than the younger people. Overall the data suggest that older people will be at a disadvantage in the performance of computer-based data entry work to the extent to which speed of responding is emphasized. However, if speed of responding is not a critical element of performance they will be able to achieve comparable levels of performance to that of younger people.