An experimental adaptive nulling receiver utilizing the samplematrix inversion algorithm with channel equalization

The authors explore two ideas for effectively achieving channel equalization within the framework of a narrowband sidelobe canceler. The first approach relies primarily on digital equalization to enhance conventional sample matrix inversion (SMI) performance, whereas the second utilizes feedback to extend the SMI method into the realm of analog adaptive cancellation. An experimental four-channel receiver that supports open-loop and closed-loop operation is described. As implemented, three different canceler modes are possible: feedforward, feedback, and a tandem feedback/feedforward combination. All three modes have been successfully demonstrated in bench experiments with a broadband noise source using the SMI algorithm. Cancellation ratios in excess of 50 dB have been achieved in a four-channel testbed system     

Call routing to distributed queues: Is FIFO really better than MED?

New services providing automatic call distribution in the network have been one of the most hotly contested areas in the USA telecommunications arena in recent years. This has been fueled by increasing demand from large corporations for intelligent network routing that will keep their geographically distributed telemarketing/service centers operating with maximum efficiency. This paper compares two basic strategies for a network call distributor: a centralized FIFO queue and a distributed queueing strategy called Minimum‐Expected‐Delay (MED). According to MED, a central controller routes each arrival to the node that minimizes its expected delay (waiting time). Our main result qualifies the conventional wisdom that perceives FIFO as optimal. We show that the waiting time under FIFO is not stochastically smaller than that under MED. Furthermore, we prove that the waiting time distribution functions intersect at a single point. Numerical experiments suggest that, for certain performance criteria and over a range of parameters of interest, MED can actually outperform FIFO. This revised version was published online in June 2006 with corrections to the Cover Date.     

Native-oxide-based selective area growth of InP nanowires via metal-organic molecular beam epitaxy mediated by surface diffusion

The growth of InP nanowires on an InP(111) B substrate is reported. The substrate native oxide was not removed from the surface prior to growth. Nanowires were grown at 400 °C from gold catalysts in a selective area manner, without bulk growth. Unlike SiO(2)-based metal-organic molecular beam epitaxy selective area growth, the growth reported here is mediated by surface diffusion with a characteristic diffusion length of 4 μm, about an order of magnitude larger than values for diffusion on bare substrates. A pre-growth heating treatment at 450 °C was found to increase the yield of nanowire nucleation from the gold catalysts.     

Borders: An Efficient Algorithm for Association Generation in Dynamic Databases

We consider the problem of finding association rules in a database with binary attributes. Most algorithms for finding such rules assume that all the data is available at the start of the data mining session. In practice, the data in the database may change over time, with records being added and deleted. At any given time, the rules for the current set of data are of interest. The naive, and highly inefficient, solution would be to rerun the association generation algorithm from scratch following the arrival of each new batch of data. This paper describes the Borders algorithm, which provides an efficient method for generating associations incrementally, from dynamically changing databases. Experimental results show an improved performance of the new algorithm when compared with previous solutions to the problem.     

How to Pack a Punch – Why 3D Batteries are Essential

The miniaturization of implantable medical devices, remote microsensors and transmitters, “smart” cards, and Internet of Things (IoT) systems is impeded by the absence of high‐performance micro‐size power sources. Insufficient areal energy density from thin‐film planar microbatteries has inspired a search for three‐dimensional microbatteries (3DMB) with the use of low‐cost and efficient micro‐ and nano‐scale materials and techniques. In our short review, we present our outlook on the state‐of‐the‐art development of advanced 3D‐microbattery designs and methods of the fabrication of electrode materials. Special attention is given to the 3D‐printing approach, which holds many opportunities for the mass production of microbatteries and their direct integration with electronic devices.     

Phased array antenna calibration and pattern prediction usingmutual coupling measurements

A technique which utilized the inherent mutual coupling in an array to both calibrate and predict the radiation patterns of a phased-array antenna is investigated. The only restriction of the technique is that the ability to transmit and receive with pairs of the array elements is required. The theory associated with array mutual coupling and its relationship to both array calibration and array patterns is discussed. The design of a test bed phased-array antenna is covered. The mutual coupling technique (MCT) is used experimentally to calibrate the test array as well as to predict the array radiation patterns. It is shown that the results obtained by MCT are in good agreement with conventional far-field measurements     

Metallic nanobowls by galvanic replacement reaction on heterodimeric nanoparticles

Well-defined metallic nanobowls can be prepared by extending the concept of a protecting group to colloidal synthesis. Magnetic nanoparticles are employed as "protecting groups" during the galvanic replacement of silver with gold. The replacement reaction is accompanied by spontantous dissociation of the protecting groups, leaving behind metallic nanobowls.