Experimental investigation on the piezo-composite actuator with piezoelectric single-crystal layer

Studies on muscle mimicking actuators have increased in the last two decades due to the possibility of various applications for compact lightweight actuators including small unmanned aircrafts, missile, and biomimetic robots. Piezoelectric materials have been used in a variety of applications ranging from shape control of structure and active vibration control of structure to noise suppression due to compact size and good frequency response. Conventional polycrystal piezoelectric ceramic materials, however, have limited actuating strains and displacement, hindering their use in actuators for small aerospace vehicles. In this study, the design and fabrication method of an actuator with a piezoelectric single-crystal layer were investigated to increase the actuation strain and displacement. From a comparison of the performance of the LIPCA-C2 and LIPCA-S prototypes, it was found that the new LIPCA-S2, which has much higher coefficient of the unimorph actuator, can generate an actuating displacement more than twice that of LIPCA-C2.     

Mechanism of Macrosegregation Formation in Continuous Casting Slab: A Numerical Simulation Study

Metallurgical and Materials Transactions B - Solidified shell bulging is supposed to be the main reason for slab center segregation, while the influence of thermal shrinkage rarely has been...     

Preparation and properties of novel pH‐sensitive core−shell microspheres for enhanced oil recovery

A novel pH‐sensitive core?shell microsphere was synthesized by growing sodium acrylate as a shell on crosslinked polyacrylamide particles as the core by surface‐initiated atom transfer radical polymerization. The structures and characteristics of the microspheres were confirmed by Fourier transform infrared spectroscopy, ¹H NMR spectroscopy, SEM, transmission electron microscopy and AFM. The viscosity and size of the microspheres in response to changes in pH value were also investigated. As a kind of potential profile control and flooding agent, the performances of permeability reduction and enhanced oil recovery were studied in designed experiments. © 2017 Society of Chemical Industry     

Two photoluminescent polymers based on fluorene and 2,4,6‐triphenyl pyridine: Synthesis and electroluminescence

Two fluorene and triphenyl pyridine‐based linear and dendronized copolymers, P1 and P2 , were synthesized and fully characterized by ¹H‐NMR, ¹³C‐NMR, and matrix assistant laser desorption/ionization time‐of‐flight mass spectra, respectively. The absorption, photoluminescence (PL) behavior, and energy band gaps of P1 and P2 relative to those of polyfluorene end‐capped with benzene ( P0 ) were examined through UV–vis, photoluminescent spectra, and cyclic voltammetry. The UV–vis absorption and PL emission behavior of P0 and P1 were hardly affected by molecular architecture, while those of P2 were strongly correlated with the dendronized molecular frameworks. Cyclic voltammetry studies indicated the lower highest occupied molecular orbital energy level and wider band gap of P2 thin solid film relative to those of P0 and P1 . The new polymers were thermally stable up to 410°C. The better luminance and external quantum efficiencies of P1 relative to those of P0 in polymer light‐emitting diode (PLED) applications are due to improved electron injection, charge trapping and recombination at the pyridine sites. Through the experiments, it is found that the triphenyl pyridyl segments and excimers‐formation make pronounced contribution to long wavelength emission in P1 ‐based blue light‐emitting materials, and the analogous materials containing 2,4,6‐triphenyl pyridyl unit of P1 constitute highly attractive materials for white PLED applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

苏里格气田回注水污染防治措施

气田污水处理后回注地层是保证气田有效开发、防止污染的有效途径。文章介绍了苏里格气田在污水回注方面通过设计、施工、运行三个阶段所采取的选择安全回注地层、优化井身结构等各种防止污染措施,有力的保护了地下水资源。     

Comparison of Isolated Indentation and Grid Indentation Methods for HVOF Sprayed Cermets

This paper compares the results of two approaches of instrumented indentation for characterization of mechanical properties of HVOF coatings. Three types of HVOF sprayed coatings (Cr₃C₂-NiCr, WC-Co, (Ti, Mo)(C,N)-NiCo) were investigated by the means of isolated nanoindentation and grid indentation methods. The results of the isolated indentation revealed hardness and elastic modulus of the individual phases in very good agreement with the corresponding bulk material. The grid indentation method, based on statistical evaluation of a large number of indentations, was influenced by the carbide-matrix interface, which gave rise to a third peak apart from the two peaks corresponding to the carbides and metallic matrix. As a consequence, the bimodal Gaussian fit was insufficient and a trimodal fit had to be used. The results extracted from low load grid nanoindentations were quite close to the results of isolated indentations whereas higher load grid nanoindentation revealed overall properties of the coating.     

Institution-governed cross-domain agent service cooperation: a model for trusted and autonomic service cooperation

Constructing Virtual Organizations (VOs) by creating service cooperation (i.e. service-oriented cooperation) has become a mainstream approach for reforming the development of application software systems in Web environments. However, the inherent non-controllability of business services across different management domains has brought on the so-called ??trust?? crisis that the success and benefit of cooperation cannot be ensured. It is this crisis that cumbers the achievement of autonomic cooperation and thereby the large-scale deployment of VOs. Therefore, this paper proposes a model, called IGTASC, to conquer this crisis and make service cooperation both trusted and autonomic by developing three closely-coupled technologies: institution-governed cooperation, policy-driven self-management, and community facilitation management.     

Effect of green mate in overweight volunteers: A randomized placebo-controlled human study

Overweight and obesity have become a global epidemic and they may impair health. Traditional use and growing evidence indicate that mate (Ilex paraguariensis A. St.-Hil.) may be helpful in losing excessive weight and fat. The present randomized, double-blind, placebo-controlled study evaluated efficacy and safety of an extract from green mate in 60 overweight subjects aged 20–39 years during 6-weeks. Body composition was measured by Dual-Energy X-ray Absorptiometry (DEXA) at baseline and after 6 weeks. Body weight, body mass index (BMI), waist circumference (WC) and various safety parameters were monitored. After 6 weeks, subjects taking mate experienced a significantly greater reduction of percent of body fat (?0.3% vs. +0.6%, p = 0.04) and fat mass (?0.5 kg vs. +0.2 kg, p = 0.04) than placebo. No significant differences were observed in other measurements. No adverse events occurred and all safety parameters were within normal ranges during the study in both groups. Thus, taking green mate extract reduced body fat after 6 weeks, while the treatment was safe and well tolerated.