A taxonomic framework for autonomous service management in Service-Oriented Architecture

Since Service-Oriented Architecture （SOA） reveals the black box nature of services, heterogeneity, service dynamism, and service evolvability, managing services is known to be a challenging problem. Autonomic computing （AC） is a way of designing systems that can manage themselves without direct human intervention. Hence, applying the key disciplines of AC to service management is appealing. A key task of service management is to identify probable causes for symptoms detected and to devise actuation methods that can remedy the causes. In SOA, there are a number of target elements for service remedies, and there can be a number of causes associated with each target element. However, there is not yet a comprehensive taxonomy of causes that is widely accepted. The lack of cause taxonomy results in the limited possibility of remedying the problems in an autonomic way. In this paper, we first present a meta-model, extract all target elements for service fault management, and present a computing model for autonomously managing service faults. Then we define fault taxonomy for each target element and inter-relationships among the elements. Finally, we show prototype implementation using cause taxonomy and conduct experi- ments with the prototype for validating its applicability and effectiveness.     

The Study on Effect of Exhaust Performance According to Active Muffler Valve Spring as Followed Spring Constant

This study represents the influence on exhaust performance by active muffler valve spring. The main experimental parameters were engine speeds and torsion coil spring constants in the active muffler. When the muffler valve spring has a low spring constant of k = 0.75, the sound pressure level was low at the region of engine speed 2000 to 2500 r/min, and the velocity of exhaust gas was high at spring constant k = 0.75. When the engine speed was under 1500 r/min, the mean concentration of CO was high in case without muffler valve. When the engine speed in the range of 1600 to 2600 r/min with spring constant k = 0.75, the mean HC concentration showed the lowest value. Without muffler valve, the temperature in the muffler was higher than the case with muffler valve. This research represented that the performance of the active muffler valve spring constant k = 0.75 was higher than that without muffler valve and valve spring constant k = 0.70. Among the three cases of experimental condition, with a spring con     

Interface specific variations in the steady-state optical properties of polyfluorene thin films

The top and bottom interfaces of spin cast poly(di-n-octylfluorene) (PF8) and poly[bis(2-ethylhex-yl)fluorene] (PF2/6) films are investigated by optical absorption and emission spectroscopy. In this study both the pure polyfluorene homopolymers and random copolymers comprised of linear di-n-octyl (F8) and the branched bis(2-ethylhexyl) (F2/6) units are used. PF2/6 is noted for forming a single conformationally disordered helix whereas PF8 adopts a number of near-planar conformational isomers. PF2/6, PF8 and their copolymers form asymmetric films in which the local structure at or near the top and bottom interfaces are distinctly different. This asymmetry is least apparent in pure PF2/6 films but increases in F8 containing polymers. In polymers containing a large fraction of F2/6 monomers the substrate-polymer side exhibits chains with slightly improved intrachain structural order and also increased green band emission. The effects of thermal and solvent vapor annealing are also reported.     

Antijamming performance of a multicarrier direct-sequencespread-spectrum system

Uncoded antijamming capability of the multicarrier direct-sequence spread-spectrum system proposed by Kondo and Milstein (see ibid. vol.44, p.238-46, 1996 ) is analyzed. Joint pulse/partial-band noise jamming is considered with various subcarrier demodulator output combining schemes. We find that full-band pulse jamming maximizes the error probability for all cases considered. With Rayleigh fading and maximal-ratio combining, the multicarrier system achieves performance very close to that of the single-carrier system without fading even with a very small number of subcarriers     

Iterative decoding and channel parameter estimation algorithms for repeat-accumulate codes

The sensitivity of the iterative decoder for repeat-accumulate (RA) codes to carrier phase and channel signal-to-noise ratio estimation errors is investigated, and efficient algorithms to estimate and correct these errors are developed. The behavior of RA codes with imperfect channel estimation is different from that of turbo codes, and correction algorithms specific to RA codes must be formulated. The proposed algorithms use the soft information generated within the iterative decoder, and thus, are not only hardware-efficient, but also offer excellent performance.     

Adaptive PN code acquisition using instantaneous power-scaled detection threshold under Rayleigh fading and pulsed Gaussian noise jamming

An adaptive serial search pseudonoise (PN) code acquisition scheme is proposed, in which the detection threshold is scaled by the instantaneous received power measured prior to PN code correlation. We observe that the proposed scheme achieves significantly improved mean acquisition times compared to the conventional nonadaptive schemes under Rayleigh fading and pulsed Gaussian noise jamming. Furthermore, the proposed scheme is shown to be optimum under pulsed Gaussian noise jamming in the sense that it forces the worst case jamming fraction to unity.     

Improving the performance of turbo codes with a simple protection scheme for error-prone bit positions

It is well known that turbo codes provide highly unequal error protection within a transmitted frame. Previous attempts to exploit this fact focused mainly on adding additional redundancy to provide extra protection for the error-prone bit positions. Here, instead, we use the error-detection capability of the cyclic redundancy check (CRC), which is almost always employed in practical systems. Once a frame is declared uncorrectable by the CRC, a process termed the error-prone bit processing procedure is activated in an attempt to correct the probable error patterns which are a priori identified as being error-prone.     

Probability of error in frequency-hop spread-spectrummultiple-access communication systems with noncoherent reception

Expressions are developed for the probability of error for asynchronous frequency-hop spread-spectrum multiple-access networks using Markov hopping patterns and binary frequency shift keying (BFSK) with one symbol transmitted per hop. The expressions are exact when there is one interfering user and orthogonal BFSK is used. They provide excellent approximations when there are more than one interfering user. It is also shown that the error probability when Markov hopping patterns are used is a good approximation to the error probability when memoryless hopping patterns are used. By computing the channel capacity and the associated throughput, a simple hard decision receiver is shown to perform much better than a receiver using perfect side-information to erase the symbols transmitted on hops that were hit when all the users have the same power and one binary symbol is transmitted per hop