Perpetual effect of laser surface texturing on tribological properties of Ti3SiC2/GNP composite—A fretting wear study

Tribological properties of Ti₃SiC₂ ceramic and Ti₃SiC₂/GNP composite were investigated using fretting sliding against Si₃N₄ ball counter body at a load of 50 N for a sliding distance of 900 m, under non-textured lubricated (NTL), textured lubricated (TL) condition, and textured lubricated high temperature (TLHT). This paper presents the influence of laser surface texturing (LST) on Ti₃SiC₂ and its graphene nanoplatelets (GNP) reinforced composite established through spark plasma sintering (SPS), tested under fretting wear conditions. The coefficient of friction and wear rate of Ti₃SiC₂ and its graphene nanoplatelets reinforced composites were incontrovertibly enhanced with laser surface texturing as compared to non-textured Ti₃SiC₂ and its GNP composite. The TL surface of Ti₃SiC₂ composite reinforced with 15% GNP showed the lowest COF and wear rate. Almost negligible changes were observed for TLHT tests. The LST proved to an efficient technique for enhancing the friction and wear properties of Ti₃SiC₂ and Ti₃SiC₂/GNP composite.     

Scientific Workflow Makespan Minimization in Edge Multiple Service Providers Environment

The edge computing model offers an ultimate platform to support scientific and real-time workflow-based applications over the edge of the network. However, scientific workflow scheduling and execution still facing challenges such as response time management and latency time. This leads to deal with the acquisition delay of servers, deployed at the edge of a network and reduces the overall completion time of workflow. Previous studies show that existing scheduling methods consider the static performance of the server and ignore the impact of resource acquisition delay when scheduling workflow tasks. Our proposed method presented a meta-heuristic algorithm to schedule the scientific workflow and minimize the overall completion time by properly managing the acquisition and transmission delays. We carry out extensive experiments and evaluations based on commercial clouds and various scientific workflow templates. The proposed method has approximately 7.7% better performance than the baseline algorithms, particularly in overall deadline constraint that gives a success rate.

     

Robust phase-unwrapping algorithm with a spatial binary-tree image decomposition

The search for fast and robust phase-unwrapping algorithms remains an important problem in the development of real-time interferometric systems. Our phase-unwrapping approach uses a spatial binary-tree image decomposition to permit maximum parallelism in implementation. At each node in the tree structure, a single unwrapping decision is made between two image blocks. The unwrapping rule is derived from a statistical-estimation framework. Specifically, a maximum-likelihood estimate of the demodulation term is used. This term can be viewed as that which minimizes a discontinuity-penalizing cost function. We show that the algorithm exhibits a high level of robustness. Quantitative measures of performance are provided, and many phase maps are shown for subjective evaluation.     

Beyond utilitarian factors: User experience and travel company website successes

Travel websites are extensively used by travelers for their travel bookings, yet little is known about the hedonic effectiveness of such experiences for the customer. The end users of these websites are customers who may not always be sophisticated information system (IS) users. Further, traditional utility based measures of customer evaluation are dated with respect to the interactive nature of the technology in use and the hedonic benefits that may result from the use of the technology. The evaluation of IS needs to include hedonic measures facilitated by the interactive technology in addition to the traditional utility based measures. We propose and test an evaluation model for retail travel websites that combines the traditional utility based measures with hedonic measures which collectively create a more comprehensive measure for the IS evaluation of consumer focused websites. Thus rooted in theory, the model extends DeLone and McLean’s model of IS Success by adding the construct of User Experience. The model was tested on a sample of 255 customers of travel websites targeted at the Indian market. The results indicate that both utility based and hedonic measures are important factors for customer IS (travel website in this study) evaluation. The larger implications for theory and practice of IS evaluation are explained.     

An Artificial Nocturnal Flower via Humidity‐Gated Photoactuation in Liquid Crystal Networks

Beyond their colorful appearances and versatile geometries, flowers can self‐shape‐morph by adapting to environmental changes. Such responses are often regulated by a delicate interplay between different stimuli such as temperature, light, and humidity, giving rise to the beauty and complexity of the plant kingdom. Nature inspires scientists to realize artificial systems that mimic their natural counterparts in function, flexibility, and adaptation. Yet, many of the artificial systems demonstrated to date fail to mimic the adaptive functions, due to the lack of multi‐responsivity and sophisticated control over deformation directionality. Herein, a new class of liquid‐crystal‐network (LCN) photoactuators whose response is controlled by delicate interplay between light and humidity is presented. Using a novel deformation mechanism in LCNs, humidity‐gated photoactuation, an artificial nocturnal flower is devised that is closed under daylight conditions when the humidity level is low and/or the light level is high, while it opens in the dark when the humidity level is high. The humidity‐gated photoactuators can be fueled with lower light intensities than conventional photothermal LCN actuators. This, combined with facile control over the speed, geometry, and directionality of movements, renders the “nocturnal actuator” promising for smart and adaptive bioinspired microrobotics.     

Automated detection of exudates and macula for grading of diabetic macular edema

Medical systems based on state of the art image processing and pattern recognition techniques are very common now a day. These systems are of prime interest to provide basic health care facilities to patients and support to doctors. Diabetic macular edema is one of the retinal abnormalities in which diabetic patient suffers from severe vision loss due to affected macula. It affects the central vision of the person and causes total blindness in severe cases. In this article, we propose an intelligent system for detection and grading of macular edema to assist the ophthalmologists in early and automated detection of the disease. The proposed system consists of a novel method for accurate detection of macula using a detailed feature set and Gaussian mixtures model based classifier. We also present a new hybrid classifier as an ensemble of Gaussian mixture model and support vector machine for improved exudate detection even in the presence of other bright lesions which eventually leads to reliable classification of input retinal image in different stages of macular edema. The statistical analysis and comparative evaluation of proposed system with existing methods are performed on publicly available standard retinal image databases. The proposed system has achieved average value of 97.3%, 95.9% and 96.8% for sensitivity, specificity and accuracy respectively on both databases.     

Synthesis,Characterization and Catalytic Activities of Palladium(II) Nitroaryl Complexes

Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (¹H, ¹³C and ³¹P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh₃, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S₁ → S₀) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts.     

外加压凹槽式机械密封热分析

用ANSYS软件建立外加压凹槽式静压型机械密封的有限元分析模型,求解并分析动、静环在稳定运行过程中的温度场。利用热实体单元,添加位移约束,并引入温度场的计算结果计算密封动、静环的热应力和热变形,分析其影响因素。结果表明,动、静环密封端面在靠近内径处均产生高温,静环凹槽根部温度梯度最大;静环在内径处变形量最大而动环变形量最大处则距内径为6.5 mm(即凹槽的内侧)。     

Photocatalytic and Antibacterial Activities of Ag/ZnO Nanocomposities Fabricated by Co-Precipitation Method

A Ag/ZnO nanocomposite has been synthesized and characterized for investigating its photocatalytic activity.The morphology and particle size of the Ag/ZnO was studied by scanning electron microscope(SEM) and the microstructure of the as-synthesized nanocomposite was confirmed by X-ray diffraction(XRD) analysis.The elemental composition of the metal oxide was determined by energy dispersion spectrometry(EDS).Diffuse reflectance spectra(DRS),Photoluminescence(PL) spectra,and Fourier transform infrared spectroscopy(FTIR) were also studied for characterizing the nanocomposite.The average particle size was found to be around 20–30 nm.Photocatalytic activity of Ag/ZnO has been investigated over methyl violet(6B) dye under UV and visible light irradiation.The degradation of methyl violet(6B)dye using ZnO and Ag/ZnO was compared and found that Ag/ZnO composite is more efficient than ZnO.The rate of disappearance of dye was monitored spectrophotometrically in the maximum visible absorption wavelength and the extent of degradation was discussed in terms of Langmuir–Hinshelwood model.The Ag/ZnO composite was found capable of degrading the industrial dye effluent.Effect of H2O2addition on dye degradation by the Ag/ZnO was investigated and Ag/ZnO was found to be an effective antimicrobial agent.Reusability of Ag/ZnO catalyst was also tested.