An efficient continuous k-nearest neighbor query processing scheme for multimedia data sharing and transmission in location based services

The continuous k-nearest neighbor query is one of the most important query types to share multimedia data or to continuously identify transportable users in LBS. Various methods have been proposed to efficiently process the continuous k-NN query. However, most of the existing methods suffer from high computation time and larger memory requirement because they unnecessarily access cells to find the nearest cells on a grid index. Furthermore, most methods do not consider the movement of a query. In this paper, we propose a new processing scheme to process the continuous k nearest neighbor query for efficiently support multimedia data sharing and transmission in LBS. The proposed method uses the patterns of the distance relationships among the cells in a grid index. The basic idea is to normalize the distance relationships as certain patterns. Using this approach, the proposed scheme significantly improves the overall performance of the query processing. It is shown through various experiments that our proposed method outperforms the existing methods in terms of query processing time and storage overhead.

     

Highly Flexible and Transparent Multilayer MoS2 Transistors with Graphene Electrodes

A highly flexible and transparent transistor is developed based on an exfoliated MoS₂ channel and CVD‐grown graphene source/drain electrodes. Introducing the 2D nanomaterials provides a high mechanical flexibility, optical transmittance (～74%), and current on/off ratio (>10⁴) with an average field effect mobility of ～4.7 cm² V^?1 s^?1, all of which cannot be achieved by other transistors consisting of a MoS₂ active channel/metal electrodes or graphene channel/graphene electrodes. In particular, a low Schottky barrier (～22 meV) forms at the MoS₂/graphene interface, which is comparable to the MoS₂/metal interface. The high stability in electronic performance of the devices upon bending up to ±2.2 mm in compressive and tensile modes, and the ability to recover electrical properties after degradation upon annealing, reveal the efficacy of using 2D materials for creating highly flexible and transparent devices.     

Robust Control of multi-echelon production-distribution systems with limited decision policy (II)

A typical production-distribution system consist of three main echelons representing the retailer, distributors, and a factory each with an on-site warehouse. The system is sufficiently general and realistic to represent many industrial situations. However, decision functions and parameters have been selected to apply particularly to the production and distribution of consumer durables. The flows included in the model are materials orders, and those information flows needed to support the material and order-rate decisions.     

The optimum solidification and crucible rotation in silicon czochralski crystal growth

Silicon crystallization is very important in many industrial processes, and it is desirable that maker should have a low cost manufacturing and high efficiency for producing semiconductors. One semiconductor process is the Czochralski (CZ) silicon melt flow and this CZ process has an excellent manufacturing feature and is utilized for silicon solidification. But CZ silicon melt flow is very complicated and this defect can be erased by the numerical analysis of the melt flow. In this paper, the optimum solidification conditions were shown for crucible rotation. This is because the solidification conditions depend on crucible rotation under the cooling process and the solidification conditions were investigated on heat generation rate on crucible wall and rotation by using numerical analysis. For the numerical validations, we verified with experimental data and showed good agreement with current numerical results. The solidification regions are classified with crystal rotation and crucible rotation. For the heat generation rate, qw, the optimum heat generation rate was estimated for 20 W/cm2 and when crystal rotation and crucible rotation is 5 rpm, the maximum solidification length can be obtained and has a stable solidification.     

An efficient data-centric storage method using time parameter for sensor networks

In wireless sensor networks, various schemes have been proposed to efficiently store and process sensed data. Among them, the data-centric storage (DCS) scheme is one of the most well-known. The DCS scheme distributes data regions and stores the data in the sensor that is responsible for the region. The DCS based scheme was proposed to reduce the communication cost for transmitting data and to efficiently process exact queries and range queries. Recently, a KDDCS scheme was proposed to overcome storage hot-spots by dynamically readjusting the distributed data regions to sensors based on the K-D tree. However, the existing DCS based schemes including KDDCS suffer from query hot-spots that are formed when query regions are not uniformly distributed. As a result, it reduces the lifetime of the sensor network.In this paper, we propose a new DCS based scheme, called Time-Parameterized Data-Centric Storage (TPDCS), that avoids the problems of storage hot-spots and query hot-spots. To decentralize the skewed data and queries, the data regions are assigned by a time dimension as well as data dimensions in our proposed scheme. Therefore, TPDCS extends the lifetime of sensor networks. It is shown through various experiments that our scheme outperforms the existing schemes.     

Subsurface object sensing with a multifrequency microwave radiometer

Experimental results are reported for sensing of subsurface objects with a multifrequency radiometer (MFRAD) system. Properties of the MFRAD system are reviewed, and the calibration and experimental procedures are discussed. Results with subsurface metallic, styrofoam, and plastic targets are then provided that demonstrate an oscillatory behavior in brightness temperatures versus frequency in the presence of a subsurface object. Measured data are also compared with a simple layered medium brightness temperature model and show reasonable agreement with predicted trends of brightness temperatures versus frequency. The oscillatory behaviors versus frequency obtained in the presence of both metallic and nonmetallic subsurface objects should prove advantageous for designing object detection procedures.     

Angle-of-arrival anemometry by means of a large-aperture Schmidt-Cassegrain telescope equipped with a CCD camera

The frequency spectrum of angle-of-arrival (AOA) fluctuations of optical waves propagating through atmospheric turbulence carries information of wind speed transverse to the propagation path. We present the retrievals of the transverse wind speed, upsilon b, from the AOA spectra measured with a Schmidt-Cassegrain telescope equipped with a CCD camera by estimating the "knee frequency," the intersection of two power laws of the AOA spectrum. The rms difference between 30 s estimates of upsilon b retrieved from the measured AOA spectra and 30s averages of the transverse horizontal wind speed measured with an ultrasonic anemometer was 11 cm s(-1) for a 1 h period, during which the transverse horizontal wind speed varied between 0 and 80 cm s(-1). Potential and limitations of angle-of-arrival anemometry are discussed.     

Effect of PEDOT:PSS–molecule interface on the charge transport characteristics of the large-area molecular electronic junctions

We have studied the effect of the PEDOT:PSS–molecule contact on the electrical characteristics of molecular junctions consisting of N-alkanedithiol and naphthalenethiol molecules. In this study, we experimentally investigated the properties of PEDOT:PSS-interlayer molecular junctions as they depended on the two kinds of PEDOT:PSS films (the pure PEDOT:PSS film and the dimethyl sulfoxide (DMSO)-modified PEDOT:PSS film) and their thermal annealing treatment. We observed that the electrical properties of these molecular junctions are influenced by the morphology and conductivity of the PEDOT:PSS films and by the thermal treatment. In particular, the resistance of the PEDOT:PSS-interlayer molecular junctions depended on the kind of PEDOT:PSS film and the temperature, within the range of elevated temperatures (higher than room temperature) tested. These experimental results are explained by the change of the interfacial properties of the PEDOT:PSS–molecule contact, which are influenced by the morphology change of the PEDOT:PSS film and the removal of residual DMSO or water from the interface.