A polarimetric CFAR ship detector based on the joint probability function of simulated first-order Markov chains

In this work, a novel ship detection procedure is presented for radar signals whose backscattering power is of the same order while their polarimetric characteristics differ greatly. The stochastic nature of the polarimetric characteristics of the background (clutter) and the target signal (ship) can be adequately described by first-order Markov chains (FMCs). The proposed feature corresponds to the joint probability of sequential states of variable finite sequential segments of the FMCs. The classic Constant False Alarm Rate (CFAR) detection theory is adapted to the discrete space of the Markov experimental distributions of the proposed feature while the adaptive thresholding technique is overcome by considering a global model for describing the clutter. Performance assessment of the proposed detection procedure is carried out by means of three sets of FMCs each one corresponding to a clutter-target pair for different lengths of the finite FMC segments. The experimental results present high detection scores making the proposed detection procedure ideal for signals characterized by the Markov property. A comparative study of previous detection approaches has been implemented that shows the superiority of the proposed detection procedure.     

An efficient discrete event model of assembly/disassembly production networks

This paper develops a discrete event simulation model of assembly/disassembly (AD) production networks with finite buffers and unreliable machines. The model is an extension of a previous continuous flow model, which simulates the system only when a machine's production rate is altered. The events causing changes in the production rates are: a machine fails or is repaired and a buffer becomes full, empty, not full, or not empty. During operation between two events the system runs deterministically. Thus, given the state of the system (machine cumulative production, buffer levels and their statistics) at the time of occurrence of some event, the corresponding state variables upon the occurrence of the next event can be updated using analysis. The proposed model does not use repair, not-full, and not-empty events. This is achieved by considering the machine downtimes as transient times in which no parts are produced and by developing more complex state equations. Numerical results show that the model combines speed and accuracy.     

This is not classified: everyday information seeking and encountering in smart urban spaces

We present a multipronged comparative study of citizens’ self-proclaimed information needs and actual information seeking behavior in smart urban spaces. We first conducted several user studies to identify the types of information services that citizens believed to be useful in urban setting utilizing methods ranging from contextual inquiry with lo-fi prototypes to “card sorting” exercise with a separate set of participants, and finally to implementing selected services. We then made a sizeable constructive intervention into the urban space by deploying in a city center 12 large, interactive public displays called “hotspots” to offer a wide range of previously identified information services. We collected comprehensive qualitative and quantitative data on the usage of the hotspots and their services by the general public during 13 months. Our study reveals discrepancies between a priori and a posteriori information seeking strategies extracted from the self-proclaimed information needs and the actual usage of the hotspots.     

Mass transfer properties of osmotic solutions. II. Diffusivities

Abstract

Mass transport properties of osmotic solutions are important in controlling osmotic dehydration process. In the first paper of the series “Mass Transfer Properties of Osmotic Solutions”;, data of water activities, osmotic pressure, osmosities or osmolalities and solute activities are presented. In the present paper, the literature data on diffusivities of both binary and multi‐component osmotic solutions are presented. Some aspects of measurement methodology and mass transfer modeling are also discussed.     

Development of an innovative information system: a fish identification e-key with update capabilities

A dichotomous identification key organizes fishes based on their similarities and differences, and is an essential tool in which ichthyologists, biologists, fishery biologists and others can use for accurate identification of specimens or finding information on correct names, biology and distribution of species. This research work focuses on the development and implementation of a totally new information system that is able to identify correctly fish species names. The developed system is a fully interactive fish identification e-key, which can be used in both forms; locally and remotely via the World Wide Web. This new dichotomous classification e-key provides the capability to identify any species in a compact and easy to use environment, which gives the user excellent operation capabilities and complete information about all included fish species. Moreover, the application provides the capability to search for a random fish species and to show a list which includes all the fish species that currently exist in the application's database. There is an extra attribute that makes the new system novel, and this is its expandability: the information system is fully dynamic having the capability to be extended every time a new species is identified. This attribute is innovative because, until now, there is not any fish identification e-key that gives the user the capability to insert new fish species into the application's database.     

Wide-field Fizeau imaging telescope: experimental results

A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described.     

A ferromagnetic linear trinuclear Ni(II)-Schiff base complex supported by phenoxo and cinnamato bridges

A new linear trinuclear nickel(II) complex, [Ni₃(salme)₂(OCn)₄] (Hsalme = 2-[(3-methylamino-propylimino)-methyl]-phenol, OCn = cinnamate), showing weak ferromagnetic coupling (J = 1.8(1) cm⁻¹) through phenoxo and a novel tridentate bridging mode (1κ²OO′:2κO′) of the cinnamate ligand has been synthesized and structurally characterized by X-ray crystallography.     

Adjusting transport segmentation policy of DTN Bundle Protocol under synergy with lower layers

We assess Delay-Tolerant Network (DTN) performance in space under the scope of adjusting protocol data unit (PDU) size at various layers. We quantify the importance of combinatively adjusting size of DTN bundles, transport packets, and link frames. Through simulations, our paper reveals trade-offs that involve file delivery time, transmission effort of sending nodes, and memory resources release rate. Based on our findings, we propose a transport adaptation scheme that dynamically adjusts DTN bundle and transport packet size by means of heuristic search. To our knowledge, this is the first study to examine transport segmentation policy and interaction among various layers of the DTN protocol stack.