Sketched oxide single-electron transistor

Devices that confine and process single electrons represent an important scaling limit of electronics. Such devices have been realized in a variety of materials and exhibit remarkable electronic, optical and spintronic properties. Here, we use an atomic force microscope tip to reversibly 'sketch' single-electron transistors by controlling a metal-insulator transition at the interface of two oxides. In these devices, single electrons tunnel resonantly between source and drain electrodes through a conducting oxide island with a diameter of ～1.5 nm. We demonstrate control over the number of electrons on the island using bottom- and side-gate electrodes, and observe hysteresis in electron occupation that is attributed to ferroelectricity within the oxide heterostructure. These single-electron devices may find use as ultradense non-volatile memories, nanoscale hybrid piezoelectric and charge sensors, as well as building blocks in quantum information processing and simulation platforms.     

Resistance switching of heteroepitaxial Cr-doped SrZrO<Subscript>3</Subscript> thin films

Heteroepitaxial Cr-doped SrZrO₃ thin films were grown on 200 nm-thick SrRuO₃ films deposited on SrTiO₃ (100) substrates by pulsed laser deposition. The Cr-doped SrZrO₃ films on the SrRuO₃ bottom electrode exhibited an XRD peak for the (hh0/00l) planes of SrZrO₃ and SrRuO₃ thin films, showing a good epitaxial relationship. The I–V characteristics of the Au/Cr-doped SrZrO₃/SrRuO₃ MIM structures revealed resistance switching behavior with an ON/OFF resistance ratio of 20.     

Active control of low-frequency noise in bubbly water-filled pipes

This paper describes an active silencer system for low-frequency noise in water-filled pipes, with implementation in marine vessels and structures in mind. Active noise control in underwater environment has its unique challenges arising from bubbles. In this light the effect of bubbles on active noise control in water-filled pipes is explored, and a design guideline for a robust active silencer is proposed. The silencer consists of an underwater sound source, an error hydrophone, and an electronic controller programmed with an adaptive filter. The adaptive filter is updated using the filtered-x least mean square algorithm. Estimation of the incoming noise is performed using an adaptive notch filter. The performance of the active silencer is tested for pure tone noises below 500 Hz in a water-filled pipe connected to a reservoir. Notable reduction of noise is achieved with varying degrees of success at different bubble fractions.

     

An Efficient Anti-collision Protocol for Fast Identification of RFID Tags

Tag collision prevention/resolution for radio frequency identification (RFID) tags is one of the most significant issues for fast tag identification. This paper proposes a new anti-collision protocol that has objective of minimizing the tag identification delay. The proposed scheme reduces the tag collisions by allocating exclusive timeslot to each tag using identified timeslot information. Performance evaluation based on numerical and simulation results shows that the proposed anti-collision method improves RFID identification performance.     

A Delay-Tolerant Virtual Tunnel Scheme for Asynchronous MAC protocols in WSN

Typically, asynchronous MAC protocols are used to monitor a significant facility for rare events or to detect an intrusion in wireless sensor networks. Moreover, asynchronous MAC protocols can achieve high energy efficiency due to the fact that there is no periodic control frame. However, asynchronous MAC protocols have the problem of long end-to-end delay time caused by the absence of precedent time synchronization per link. This paper proposes a new scheme, called virtual tunnel (VT), which can reduce the delivery delay of asynchronous MAC protocols in multi-hop environment. The VT scheme can achieve approximated duty cycle synchronization with on-demand approach. In this scheme, through the estimation of next wakeup time of peer node, without exceptional process, each node on the transmission path can improve end-to-end delay in multi-hop topologies. And it becomes low power consumption by reducing unnecessary retransmissions. Additionally, we devise the protection method of VT. In our simulation results, end-to-end delay according to hop counts and traffic amount is compared with the X-MAC that is an asynchronous protocol recently developed. Furthermore, it is shown that the VT scheme decreases energy consumption due to the lower end-to-end delay than the X-MAC in multi-hop topologies.     

Energy efficient clustering algorithm for the mobility support in an IEEE 802.15.4 based wireless sensor network

The traditional clustering algorithm is an advanced routing protocol for enhancing an energy efficiency, which selects a cluster head and transmits the aggregated data arriving from the sensor nodes in the cluster to a gateway. However, the existing literature works were not suitable for an IEEE 802.15.4 beacon enabled mode and did not provide the combined solution for an energy efficient scheduling and handover of the sensor nodes. To address these problems, in this paper, we propose an energy efficient clustering algorithm for the mobility support in IEEE 802.15.4 networks. The simulation results show that the proposed scheme reduces the energy consumption and the packet loss, thus enhancing the performance.

     

A low-overhead networking mechanism for virtualized high-performance computing systems

The use of virtualized parallel and distributed computing systems is rapidly becoming the mainstream due to the significant benefit of high energy-efficiency and low management cost. Processing network operations in a virtual machine, however, incurs a lot of overhead from the arbitration of network devices between virtual machines, inherently by the nature of the virtualized architecture. Since data transfer between server nodes frequently occurs in parallel and distributed computing systems, the high overhead of networking may induce significant performance loss in the overall system. This paper introduces the design and implementation of a novel networking mechanism with low overhead for virtualized server nodes. By sacrificing isolation between virtual machines, which is insignificant in distributed or parallel computing systems, our approach significantly reduces the processing overhead in networking operations by up to 29% of processor load, along with up to 36% of processor cache miss. Furthermore, it improves network bandwidth by up to 8%, especially when transmitting large packets. As a result, our prototype enhances the performance of real-world workloads by up to 12% in our evaluation.     

Analysis of C-reactive protein on amide-linked N-hydroxysuccinimide-dextran arrays with a spectral surface plasmon resonance biosensor for serodiagnosis

A new label-free array system using amide-linked (AL) NHS-dextran and a spectral SPR biosensor are presented for the high-throughput analysis of C-reactive protein (CRP) in human sera. The AL NHS-dextran layer on the surface of gold arrays was composed of an amide linkage between NHS-modified carboxymethyl-dextran and amine-modified 11-mercaptoundecanoic acid. The topology of the AL NHS-dextran layer was analyzed by atomic force microscopy, and it was found to be superior to the previously used epoxide-linked carboxymethyl-dextran layer in its immobilization of proteins. Specific immunoreactions and a dose-dependent increase of SPR signals were demonstrated on the AL NHS-dextran layer. Then, the label-free array system was successfully applied to the rapid analysis of CRP in 120 human sera. CRP levels in human sera determined by the array-based spectral SPR biosensor showed a good correlation with those determined by the latex-enhanced turbidimetry immunoassay (n = 120, r = 0.945, p < 0.0001). Thus, the array-based spectral SPR biosensor based on the AL NHS-dextran surface is a potential system for rapid and label-free serodiagnosis of human diseases.     

Simulation of clutch actuation system for commercial vehicle

Generally, a method of a hysteresis loop is used to show the property of the clutch system in the design process. This represents the load by a pedal travel which is a useful data for designing a vehicle for the comfort of the driver. Transfer torque of manual shift gear types for heavy duty vehicles is too high. Therefore unlike passenger car air pressure is added to the clutch system in addition to the fluid pressure. In this case it is hard to predict nonlinear element to control the hysteresis because of the addition of the components. In this paper theoretical model of the system components involving variables such as mass, stiffness and damping is developed and simulated. The results of the actual test of the clutch system are compared with simulation.