INTEGRATED OPERATOR GENETIC ALGORITHM FOR SOLVING MULTI-OBJECTIVE FLEXIBLE JOB-SHOP SCHEDULING

In the flexible job-shop scheduling problem （FJSP）, each operation has to be assigned to a machine from a set of capable machines before alocating the assigned operations on all machines. To solve the multi-objective FJSP, the Grantt graph oriented string representation （GOSR） and the basic manipulation of the genetic algorithm operator are presented. An integrated operator genetic algorithm （IOGA） and its process are described. Comparison between computational results and the latest research shows that the proposed algorithm is effective in reducing the total workload of all machines, the makespan and the critical machine workload.

柔拓扑空间的连通性

研究了柔拓扑空间的连通性,在柔拓扑空间中定义了隔离柔集,利用隔离柔集给出了连通柔拓扑空间和连通柔集的概念,并为连通柔拓扑空间提供了等价的定义。通过引入了柔拓扑空间之间的连续序同态,证明了柔拓扑空间的连通性在连续序同态下具有不变性,最后得出了柔拓扑空间连通的几个充分条件。

Global Analysis of a Flexible Riser

The mechanical performance of a flexible riser is more outstanding than other risers in violent environmental conditions. Based on the lumped mass method, a steep wave flexible riser configuration attached to a Floating Production Storage and Offioading （FPSO） has been applied to a global analysis in order to acquire the static and dynamic behavior of the flexible riser. The riser was divided into a series of straight massless line segments with a node at each end. Only the axial and torsional properties of the line were modeled, while the mass, weight, and buoyancy were all lumped to the nodes. Four different buoyancy module lengths have been made to demonstrate the importance of mode selection, so as to confirm the optimum buoyancy module length. The results in the sensitivity study show that the flexible riser is not very sensitive to the ocean current, and the buoyancy module can reduce the Von Mises stress and improve the mechanical performance of the flexible riser. Shorter buoyancy module length can reduce the riser effective tension in a specific range of the buoyancy module length when other parameters are constant, but it can also increase the maximum curvature of the riser. As a result, all kinds of the riser performances should be taken into account in order to select the most appropriate buoyancy module length.

乘积柔拓扑空间及其性质

先定义了柔集的笛卡尔积,射影序同态,柔拓扑空间的基、子基等概念,在此基础上定义了乘积柔拓扑空间,给出了乘积柔拓扑空间的等价描述以及乘积柔拓扑空间的一些基本性质,证明了一族满足T0分离性(resp.,T1分离性,T2分离性,正则分离性,连通性)的柔拓扑空间的乘积柔拓扑空间仍然满足这种性质,同时证明了第二可数是N0-可乘性质。

Development of Integrated Precision Vibration-Assisted Micro-Engraving System

A novel precision vibration-assisted micro-engraving system was developed by the integration of fast tool servo and ultrasonic elliptical vibration system, in which the flexure hinge was designed to avoid backlash and PID control algorithm was established to guarantee specific precision. Apart from experimental validation of the performance of the system, various micro-V-grooves cutting experiments on aluminum alloy, ferrous material and hard cutting material were performed, in which Kistler force sensor was used to measure cutting force. Through experiments, it was clear that the vibration-assisted micro-engraving system can ensure good quality of micro-V-grooves and reduce cutting force by about 60% compared with traditional removal process without ultrasonic vibration.

Mechanics of flexible and stretchable piezoelectrics for energy harvesting

As rapid development in wearable/implantable electronic devices benefit human life in daily health monitoring and disease treatment medically, all kinds of flexible and/or stretchable electronic devices are booming, together with which is the demanding of energy supply with similar mechanical property. Due to its ability in converting mechanical energy lying in human body into electric energy, energy harvesters based on piezoelectric materials are promising for applications in wearable/implantable device's energy supply in a renewable, clean and life-long way. Here the mechanics of traditional piezoelectrics in energy harvesting is reviewed, including why piezoelectricity is the choice for minor energy harvesting to power the implantable/wearable electronics and how. Different kinds of up to date flexible piezoelectric devices for energy harvesting are introduced, such as nanogenerators based on Zn O and thin and conformal energy harvester based on PZT. A detailed theoretical model of the flexible thin film energy harvester based on PZT nanoribbons is summarized, together with the in vivo demonstration of energy harvesting by integrating it with swine heart. Then the initial researches on stretchable energy harvesters based on piezoelectric material in wavy or serpentine configuration are introduced as well.

Progress in flexible organic thin-film transistors and integrated circuits

Organic thin-film transistor constructs the headstone of flexible electronic world such as conformable sensor arrays and flexible active-matrix displays. With solutionprocessed methods, it forges ahead toward large-area, lowcost manufacturing goals. As an indispensable complement to traditional silicon-based transistors, organic thin-film field-effect transistors have made great progress in materials,performance, bending capacity, and integrated circuits in recent few years. Flexible transistors and circuitry have extremely promising application prospects and possess irreplaceable status in foldable displays, artificial skins and bendable smart cards. In this review, we will discuss the evolution of flexible organic transistors and integrated circuits in terms of material, fabrication as well as application.

Flexible piezoelectric nanogenerators based on a fiber/ZnO nanowires/paper hybrid structure for energy harvesting

We present a novel, low-cost approach to fabricate flexible piezoelectric nano- generators （NGs） consisting of ZnO nanowires （NWs） on carbon fibers and foldable Au-coated ZnO NWs on paper. By using such designed structure of the NGs, the radial ZnO NWs on a cylindrical fiber can be utilized fully and the electrical output of the NG is improved. The electrical output behavior of the NGs can be optionally controlled by increasing the fiber number, adjusting the strain rate and connection modes. For the single-fiber based NGs, the output voltage is 17 mV and the current density is about 0.09 μA·cm^-2, and the electrical output is enhanced greatly compared to that of previous similar micro-fiber based NGs. Compared with the single-fiber based NGs, the output current of the multi-fiber based NGs made of 200 carbon fibers increased 100-fold. An output voltage of 18 mV and current of 35 nA are generated from the multi-fiber based NGs. The electrical energy generated by the NGs is enough to power a practical device. The developed novel NGs can be used for smart textile structures, wearable and self-powered nanodevices.

Magnetically induced micropillar arrays for an ultrasensitive flexible sensor with a wireless recharging system

Significant efforts have been devoted to enhancing the sensitivity and working range of flexible pressure sensors to improve the precise measurement of subtle variations in pressure over a wide detection spectrum. However,achieving sensitivities exceeding 1000 kPa^(-1) while maintaining a pressure working range over 100 kPa is still challenging because of the limited intrinsic properties of soft matrix materials. Here, we report a magnetic field-induced porous elastomer with micropillar arrays(MPAs) as sensing materials and a well-patterned nickel fabric as an electrode. The developed sensor exhibits an ultrahigh sensitivity of 10,268 kPa^(-1)(0.6–170 kPa) with a minimum detection pressure of 0.25 Pa and a fast response time of 3 ms because of the unique structure of the MPAs and the textured morphology of the electrode. The porous elastomer provides an extended working range of up to 500 kPa with long-time durability. The sophisticated sensor system coupled with an integrated wireless recharging system comprising a flexible supercapacitor and inductive coils for transmission achieves excellent performance. Thus, a diverse range of practical applications requiring a low-to-high pressure range sensing can be developed. Our strategy, which combines a microstructured high-performance sensor device with a wireless recharging system, provides a basis for creating next-generation flexible electronics.