Evaluation of Cloud services: A fuzzy multi-criteria group decision making method

This paper presents a fuzzy multi-criteria group decision making method for evaluating the performance of Cloud services in an uncertain environment. Intuitionistic fuzzy numbers are used to better model the subjectivity and imprecision in the performance evaluation process. An effective algorithm is developed based on the technique for order preference by similarity to the ideal solution and the Choquet integral operator for adequately solving the performance evaluation problem. An example is presented for demonstrating the applicability of the proposed method for solving the multi-criteria group decision making problem in real situations

Observer-based fuzzy control design with adaptation to delay parameter for time-delay systems

This paper is concerned with the problem of observer-based fuzzy stabilization for time-delay systems. The time-delay under consideration is assumed to be a constant time-delay, but not known exactly.A new design method is proposed for an observer-based fuzzy controller with adaptation to the time-delay. The designed controller simultaneously contains both the current and past state information of the systems and can be derived by solving a set of linear matrix inequalities (LMIs). The existence of the controller is equivalent to that of a controller for time-delay systems where the constant time-delay is known exactly. A numerical example is given to illustrate the effectiveness of the design method

Energy-efficiency Optimization Schemes Based on SWIPT in Distributed Antenna Systems

In this paper, we intend to study the energy efficiency (EE) optimization for a simultaneous wireless information and power transfer (SWIPT)-based distributed antenna system (DAS).Firstly, a DAS-SWIPT model is formulated, whose goal is to maximize the EE of the system. Next, we propose an optimal resource allocation method by means of the Karush-Kuhn-Tucker condition as well as an ergodic method. Considering the complexity of the ergodic method, a suboptimal scheme with lower complexity is proposed by using an antenna selection scheme. Numerical results illustrate that our suboptimal method is able to achieve satisfactory performance of EE similar to an optimal one while reducing the calculation complexity

Novel composite siro-spinning with forced migrations of filaments

In this study, a novel composite siro-spinning method with cyclically migrating filaments was developed as a simple and safe way to enhance filament-staple-fiber coherence. The novel composite siro-spinning method was theoretically demonstrated to produce a yarn with migrated filaments clasping both internal and external fibers. It was predicted that migrated filaments of the novel composite sirospun yarn were not straight enough to resist yarn tensile drawing as the filament parallelism with the yarn axis decreased. However, migrated filaments could clasp the staple fibers firmly to enhance filament-staple-fiber coherence, contributing an excellent frictional resistance of the novel composite yarn. Experiments were then conducted to validate the demonstration. Experimental results proved that the novel composite sirospun yarn had cyclic filament immersion and exposure appearance, resulting in medium hairiness and yarn imperfection after comparison with corefil sirospun and siro corefil yarns. The novel composite sirospun yarn with severe filament migrations had poor filament straightness, but filament deformations that were effective in clamping staple fibers. Therefore, the novel composite sirospun yarn had less strength, but greater frictional resistance than corefil sirospun and siro corefil yarns

Transition from internal to surface crack initiation of a single-crystal superalloy in the very-high-cycle fatigue regime at 1100 °C

Transition from internal to surface crack initiation is controlled by oxidation assisted fatigue-crack process in the very-high-cycle fatigue regime. Between 760 and 1000 °C, single crack initiation site is associated with internal casting defect, followed by a crystallographic Stage I propagation. By contrast, multiple surface crack initiation sites appear at 1100 °C, as the consequence of internal oxide penetration. The fatal crack follows a Mode I propagation and oxygen can diffuse into the material along the crack path. γ′-phase depletion appears surrounding the oxidised and cracked regions, while localised rafting can occur close to the crack tip

Comparative study of ring yarn properties spun with static and rotary grooved contact surfaces

Spinning with a static contact surface is an energy-saving method to reduce spun yarn hairiness; however, the spun yarn irregularity and tensile properties are deteriorated. To prohibit the deteriorations, this paper introduces a rotary grooved surface contacting ring spinning strand within the yarn formation zone. In theory, the modeling analysis of spinning with contact surface is conducted to reveal the prohibition mechanism of yarn irregularity and tensile property deteriorations for a rotary grooved surface. Theoretical analysis results indicated that groove-yarn surface friction could wrap the concentrated hairs onto yarn stem while block inflowing twists to the spinning strangle zone; the rotary grooved surface could reduce twist blockage and hair wrapping concentrations to better the situation after a comparison with the static grooved surface. Then, two kinds of specially-designed grooved cylinders (one was rotatable while the other was static) were used to validate the theoretical analysis. The experimental results showed that, unlike the static grooved cylinder which significantly deteriorated the original yarn unevenness CVm, the rotary achieved significant hairiness reduction without any significant deterioration of other yarn properties. This might be due to the decreased friction and twist propagation for the rotary grooved cylinder contacting the spinning strand. In this case, spinning with a rotary grooved cylinder was preferably applied in the first step to control ring spun yarn hairiness

Function of BriC peptide in the pneumococcal competence and virulence portfolio.

Streptococcus pneumoniae (pneumococcus) is an opportunistic pathogen that causes otitis media, sinusitis, pneumonia, meningitis and sepsis. The progression to this pathogenic lifestyle is preceded by asymptomatic colonization of the nasopharynx. This colonization is associated with biofilm formation; the competence pathway influences the structure and stability of biofilms. However, the molecules that link the competence pathway to biofilm formation are unknown. Here, we describe a new competence-induced gene, called briC, and demonstrate that its product promotes biofilm development and stimulates colonization in a murine model. We show that expression of briC is induced by the master regulator of competence, ComE. Whereas briC does not substantially influence early biofilm development on abiotic surfaces, it significantly impacts later stages of biofilm development. Specifically, briC expression leads to increases in biofilm biomass and thickness at 72h. Consistent with the role of biofilms in colonization, briC promotes nasopharyngeal colonization in the murine model. The function of BriC appears to be conserved across pneumococci, as comparative genomics reveal that briC is widespread across isolates. Surprisingly, many isolates, including strains from clinically important PMEN1 and PMEN14 lineages, which are widely associated with colonization, encode a long briC promoter. This long form captures an instance of genomic plasticity and functions as a competence-independent expression enhancer that may serve as a precocious point of entry into this otherwise competence-regulated pathway. Moreover, overexpression of briC by the long promoter fully rescues the comE-deletion induced biofilm defect in vitro, and partially in vivo. These findings indicate that BriC may bypass the influence of competence in biofilm development and that such a pathway may be active in a subset of pneumococcal lineages. In conclusion, BriC is a part of the complex molecular network that connects signaling of the competence pathway to biofilm development and colonization

Liquid flow spinning mass-manufactured paraffin cored yarn for thermal management and ultra-high protection

Thermal management and ultra-high protection textiles are critical for polar scientists, astronauts and firefighters. Phase change materials (PCMs) effectively retard huge thermal changes, and thermal damage by absorbing or releasing heat during phase transition. However, due to the materials and engineering challenges inherent in PCMs based textiles, commercial PCMs usually suffer with high rigidity, no-breath-ability, easy leakage and abrasion, limiting their potential applications. Herein, we proposed a mass-producible liquid flow spinning (LFS) method, in which molten paraffin is poured into continuous hollow silicon tubes and then wrapped by staple fibers to form paraffin-coated yarns (PCYs) on a friction spinning frame. The obtained PCYs showed enhanced mechanical properties (break strength of 7.80 N, wear resistance of 2000 cycles) due to the novel core-sheath yarn structure. Besides, thanks to the high melting enthalpy (60.967 J/g) of PCYs, the yarns showed the excellent temperature regulating effect. A double-sided joint PCYs fabric (PCYF) is fabricated to study the PCYs performance further, results show that the PCYF can withstand 10,000 cycles of abrasion without breakage and PCMs leakage. Furthermore, owing to the much gaps provided by the stretch fibers and interweaving points, the fabric exhibits good breathability. In particular, compared with commercial PCMs based textiles, our PCYF is superior in thermal protection performance (9 °C lower). The fireproof performance is also excellent as our PCYF can withstand flame temperatures higher than 1142 °C. The PCYs production method provided here could pave the way for human thermal protection textiles

Roadmap on nanogenerators and piezotronics

Piezoelectric nanogenerator (PENG) was first introduced by using piezoelectric nanowires for converting tiny mechanical energy into electric power. Research in nanogenerators has been vastly expanded in the last decade due to the invention of the triboelectric nanogenerator (TENG). As of today, the definition of nanogenerator has far exceeded its traditional meaning, and it represents a field that uses the Maxwell’s displacement current to convert mechanical energy into electric power/signal. This field is attracting a wide range of interest due to the huge advances in the internet of things, big data, sensor network, robotics, and artificial intelligence. TENGs are playing a key role in harvesting high entropy energy distributed in our living environment for effective driving of distributed electronics and systems.</p