Tunable D peak in gated graphene

We report the gate-modulated Raman spectrum of defective graphene. We show that the intensity of the D peak can be reversibly tuned by applying a gate voltage. This effect is attributed to chemical functionalization of the graphene crystal lattice, generated by an electrochemical reaction involving the water layer trapped at the interface between silicon and graphene.     

Round Robin Test for composite-to-brick shear bond characterization

The paper presents the experience of a working group within the RILEM Technical Committee 223-MSC ??Masonry Strengthening with Composite materials??, aimed at developing a standardized, reliable procedure for characterizing the bonding mechanism of masonry elements strengthened with composite materials under shear actions. Twelve laboratories from European universities and research centers were involved. Two different set-ups were compared, for single-lap and double-lap shear tests (the latter in two versions). Four kinds of fiber fabrics, i.e., glass, carbon, basalt and steel, were applied with epoxy resins (wet lay-up system) to clay brick units, for a total of 280 monotonic tests. The results provided information regarding the response of externally bonded-to-brick composites in terms of observed failure mechanisms, load capacity, effective transfer length, and bond shear stress?Cslip behavior. The test results of the 12 laboratories constitute a set of statistically representative data which may conveniently be used for setting appropriate design provisions and guidelines.     

A GA-based movie-on-demand platform using multiple distributed servers

In this paper we present the design and explore the performance of a unicast-based distributed system for Movie-on-Demand applications. The operation of multiple servers is coordinated with the assistance of an analytical framework that provides closed-form solutions to the content partitioning and scheduling problem, even under the presence of packet losses. The problem of mapping clients to servers is solved with a genetic algorithm, that manages to provide adequate, near-optimum solutions with a minimum of overhead. While previous studies focused on the static behavior of such a system, i.e. fixed a-priori known number of N servers and K clients commencing operation at the same time instance, this paper focuses on the dynamic behavior of such a system over a period of time with clients coming and going at random intervals. The paper includes a rigorous simulation study that shows how the system behaves in terms of a variety of metrics, including the average access time over all the requested media, in response to differences in the client arrival rate or the consumed server bandwidth. As it is shown, the proposed platform exhibits excellent performance characteristics that surpass traditional approaches that treat clients individually. This has been verified to be true up to extreme system loads, proving the scalability of the proposed content delivery scheme. The significance of our findings also stems from the assumption of unreliable communications, a first for the study of complete systems in this domain.

BSPlib: The BSP programming library

BSPlib is a small communications library for bulk synchronous parallel (BSP) programming which consists of only 20 basic operations. This paper presents the full definition of BSPlib in C, motivates the design of its basic operations, and gives examples of their use. The library enables programming in two distinct styles: direct remote memory access (DRMA) using put or get operations, and bulk synchronous message passing (BSMP). Currently, implementations of BSPlib exist for a variety of modern architectures, including massively parallel computers with distributed memory, shared memory multiprocessors, and networks of workstations. BSPlib has been used in several scientific and industrial applications; this paper briefly describes applications in benchmarking, Fast Fourier Transforms (FFTs), sorting, and molecular dynamics.     

Model predictive control for wind turbines with distributed active flaps: incorporating inflow signals and actuator constraints

This paper describes the implementation of system identification and controller design techniques using model predictive control (MPC) for wind turbines with distributed active flaps for load control. An aeroservoelastic model of the 5 MW NREL/Upwind reference wind turbine, implemented in the code DU_SWAMP, is used in an industry‐based MPC controller design cycle, involving the use of dedicated system identification techniques. The novel multiple‐input multiple‐output MPC controllers, which incorporate flap actuator constraints and the use of local inflow measurement signals, are designed and implemented for various operating points. The controllers are evaluated in standard power production load cases and fatigue load reductions up to 27.3% are achieved. The distributed flaps controller scheme is also compared with simpler single‐flap single‐input single‐output and individual pitch controller schemes. Copyright © 2011 John Wiley & Sons, Ltd.     

移动机械师

一直以来我就想制作一辆伊达雷利出品的福特全顺,参加的"一套模型四人做"挑战活动成为了实现梦想的好机会. 福特全顺对于我这个年龄的人来说十分重要,该车似乎无所不在,而且看上去总是透着一股破旧肮脏的疲惫感.因此,我决定制作一辆童年印象中的该款车型.我相信仅仅制作车身是不够的,所以决定在车内和车外花费同样多的时间. 我决定制...     

Design of a scaled wind turbine with a smart rotor for dynamic load control experiments

The ever increasing size of wind turbines poses a number of design issues for the industry, like increasing component mass and fatigue loads. An interesting concept for reducing fatigue loads is the implementation of spanwise distributed devices to control the aerodynamic loading along the span of the blade, thus mitigating fluctuations in loading and adding damping to the blade modes. This is usually referred to as the smart rotor concept. In the design of such a rotor, as compared to a traditional one, the integration of sensors and actuators poses additional design challenges. In the research discussed in this paper, a scaled smart rotor was designed and constructed to study its fatigue load reduction potential. A 1.8 m diameter rotor was manufactured and equipped with trailing‐edge flaps. The flaps were based on piezo electric Thunder actuators that allow for high‐frequent actuation. The dynamic strain behaviour of the blade was analysed for optimal placement of the sensors. Several sensors that record the strains and accelerations at different locations along the blade were implemented, but the controller was based on a piezo electric strain sensor. The rotor blades were mounted on a small turbine in the Delft University's Open Jet Facility wind tunnel and a mathematical state space model was obtained by using dedicated system identification techniques. Single‐Input Single‐Output, Multi‐Input Multi‐Output ??_∞ feedback and feedforward controllers were designed, each focusing on different parts of the load spectrum. The rotor was tested at 0 and 5° yaw angles, with and without load control. A significant reduction of the dynamic loads was attained. Copyright © 2010 John Wiley & Sons, Ltd.     

Gold nanoparticle conjugated poly(p-phenylene-β-cyclodextrin)-graft-poly(ethylene glycol) for theranostic applications

Fluorescent conjugated polymers gained interest in the last decades for both imaging and targeting tumor cells for the purpose of diagnosis and treatment of cancer. In the light of this objective conjugated poly(p-phenylene) possessing β-cyclodextrin (β-CD) units in the main chain and poly(ethylene glycol) side chains is used as an imaging and therapeutic agent to target U87 and Vero cells. Additionally, imaging quality and therapy efficiency of the bare graft copolymer and its gold nanoparticle (AuNP) conjugated form were investigated and compared. It is observed that β-CD is effective not only for the imaging of the tumor cells, but also as a radiotherapy agent. Conjugation of the polymer with the AuNPs provides significant improvement in the therapeutic efficiency. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47250.