Information content of data measured with a multiple-field-of-view lidar

Lidars with multiple fields of view (MFOVs) are promising tools for gaining information on cloud particle size. We perform a study of the information content of MFOV lidar data with the use of eigenvalue analysis. The approach we have developed permits an understanding of the main features of MFOV lidars and provides a way to relate the accuracy of particle size estimation with the measurement uncertainty and the scattering geometry such as the cloud-base height and the lidar sounding depth. Second-order scattering computations are performed for an extended range of particle sizes and for a wide range of lidar fields of view (FOVs). The results obtained allow us to specify the areas of possible applications of these lidars in cloud studies. Comparison of results obtained with polarized and cross-polarized scattered components demonstrate that the cross-polarized signal should provide a more stable retrieval and is preferable when double scattering is highly dominant. Our analysis allows for the estimation of the optimal number of FOVs in the system and their angular distribution, so this work can be a useful tool for practical MFOV lidar design.     

Information discovery across multiple streams

In this paper we address the issue of continuous keyword queries on multiple textual streams and explore techniques for extracting useful information from them. The paper represents, to our best knowledge, the first approach that performs keyword search on a multiplicity of textual streams. The scenario that we consider is quite intuitive; let’s assume that a research or financial analyst is searching for information on a topic, continuously polling data from multiple (and possibly heterogeneous) text streams, such as RSS feeds, blogs, etc. The topic of interest can be described with the aid of several keywords. Current filtering approaches would just identify single text streams containing some of the keywords. However, it would be more flexible and powerful to search across multiple streams, which may collectively answer the analyst’s question. We present such model that takes in consideration the continuous flow of text in streams and uses efficient pipelined algorithms such that results are output as soon as they are available. The proposed model is evaluated analytically and experimentally, where the Enron dataset and a variety of blog datasets are used for our experiments.     

An $\tilde{O}(m^{2}n)$ Algorithm for Minimum Cycle Basis of Graphs

We consider the problem of computing a minimum cycle basis of an undirected non-negative edge-weighted graph G with m edges and n vertices. In this problem, a {0,1} incidence vector is associated with each cycle and the vector space over generated by these vectors is the cycle space of G. A set of cycles is called a cycle basis of G if it forms a basis for its cycle space. A cycle basis where the sum of the weights of the cycles is minimum is called a minimum cycle basis of G. Minimum cycle basis are useful in a number of contexts, e.g. the analysis of electrical networks and structural engineering. The previous best algorithm for computing a minimum cycle basis has running time O(m ^ω n), where ω is the best exponent of matrix multiplication. It is presently known that ω<2.376. We exhibit an O(m ² n+mn ²log n) algorithm. When the edge weights are integers, we have an O(m ² n) algorithm. For unweighted graphs which are reasonably dense, our algorithm runs in O(m ^ω ) time. For any ε>0, we also design an 1+ε approximation algorithm. The running time of this algorithm is O((m ^ω /ε)log (W/ε)) for reasonably dense graphs, where W is the largest edge weight. A preliminary version of this paper appeared in Kavitha et al. (31st International Colloquium on Automata, Languages and Programming (ICALP), pp. 846–857, 2004). T. Kavitha and K.E. Paluch were in Max-Planck-Institut für Informatik, Saarbrücken, Germany, while this work was done.     

Cache-Integrated Network Interfaces: Flexible On-Chip Communication and Synchronization for Large-Scale CMPs

Per-core scratchpad memories (or local stores) allow direct inter-core communication, with latency and energy advantages over coherent cache-based communication, especially as CMP architectures become more distributed. We have designed cache-integrated network interfaces, appropriate for scalable multicores, that combine the best of two worlds – the flexibility of caches and the efficiency of scratchpad memories: on-chip SRAM is configurably shared among caching, scratchpad, and virtualized network interface (NI) functions. This paper presents our architecture, which provides local and remote scratchpad access, to either individual words or multiword blocks through RDMA copy. Furthermore, we introduce event responses, as a technique that enables software configurable communication and synchronization primitives. We present three event response mechanisms that expose NI functionality to software, for multiword transfer initiation, completion notifications for software selected sets of arbitrary size transfers, and multi-party synchronization queues. We implemented these mechanisms in a four-core FPGA prototype, and measure the logic overhead over a cache-only design for basic NI functionality to be less than 20%. We also evaluate the on-chip communication performance on the prototype, as well as the performance of synchronization functions with simulation of CMPs with up to 128 cores. We demonstrate efficient synchronization, low-overhead communication, and amortized-overhead bulk transfers, which allow parallelization gains for fine-grain tasks, and efficient exploitation of the hardware bandwidth.     

Synthesis, structure, thermal and mechanical properties of nanocomposites based on linear polymers and layered silicates modified by polymeric quaternary ammonium salts (ionenes)

Polymer–clay composites has been prepared by melt blending an organo-bentonite with linear polymers (polyamide, polysterene and polypropylene) in a disk-screw extruder. In first time organo-clay was prepared by surface treatment of Na-forms bentonite with polymeric quaternary ammonium salts (PQAS). XRD indicated that organo-bentonite layers were exfoliated and dispersed into polyamide and polystyrene. Addition of 2 wt% organo-bentonites (optimal concentration) to polyamide increased tensile strength by 53% and Sharpy impact by 140%. With the incorporation of 2 wt% organo-bentonites (optimal concentration) into polystyrene the tensile strength increased to 28% and the Sharpy impact increased to 25%. For polypropylyne–organo-bentonites composites we did not observe delamination of layered structure, and as result absence of reinforcements. TGA showed that the polyamide and polystyrene nanocomposites have higher decomposition temperature in comparison with the original polymers.     

The motion of the free-surface separation point during the initial stage of horizontal impulsive displacement of a floating circular cylinder

The initial stage of unsteady two-dimensional flow caused by the impulsive horizontal motion of a floating circular cylinder is investigated by using methods of asymptotic analysis. Initially the cylinder is half-submerged and the liquid free surface is flat and horizontal. The liquid is of infinite depth. Then the cylinder suddenly starts to move horizontally with a speed given as a function of time. The liquid is assumed ideal and incompressible and its flow potential. The initial flow is provided by pressure-impulse theory, with an account of a possible separation of the liquid free surface from the trailing face of the rigid surface of the cylinder. The initial position of the separation point on the surface of the moving body is determined by using the condition that the fluid velocity is finite at the separation point (Kutta condition). The motion of the separation point along the surface of the cylinder is numerically determined with the help of the second-order outer solution of the problem and the Kutta condition at the moving separation point. It is shown that the length of the wetted part of the cylinder surface increases at a rate proportional to the speed of the cylinder. The speed of the separation point depends on the Froude number. The pressure on the wetted part of the cylinder can be below the atmospheric pressure for relatively high speed.     

Large and small signal distortion analysis using modified Volterra series

A new approach to the Volterra analysis of analog circuits is presented. Volterra analysis is widely used for the calculation of harmonic and intermodulation distortion products. However, the analysis is limited to circuits experiencing small signal excitations and becomes inaccurate when the input signal amplitude increases, especially when MOS transistors are involved. In this paper, we analyze the cause of this drawback, which is no other than the Taylor series’ convergence properties. Moreover, we propose a solution, by calculating the nonlinearity coefficients using a different type of polynomial expansion, the Chebyshev series. This replacement improves significantly the capabilities of Volterra analysis. We also present results comparing Chebyshev series with other types of polynomial expansions. Finally, we apply the proposed method to analyze the intermodulation distortion (IMD) of a CMOS RF power amplifier, both in the small and the large signal regimes.     

Organic Bionics: A New Dimension in Neural Communications

The term “bionics” is synonymous with the term “biomimetics” and in this context refers to the integration of human engineered devices to take advantage of functional mechanisms and structures resident in nature. The use of electrical conductors to transmit charge into and out of biological systems to affect biological processes has been the source of great scientific interest. This has inspired many to explore the possible use of electrical stimulation in promoting positive health outcomes. Advances in medical bionics technology are dependent upon eliciting precise control of the electrical energy to deliver beneficial health outcomes. The advent of carbon‐based organic conductors now provides the platform for unprecedented possibilities by which the electrical energy can be used to modulate the function of medical devices. The use of organic conductors in the field of bionics, and in particular medical bionics, as that involved with the development of devices that enable the effective integration of biology (nature) and electronics to achieve a targeted functional outcome is explored.     

The interplay of online shopping motivations and experiential factors on personalized e-commerce: A complexity theory approach

The present study aims to examine purchase behavior in personalized online shopping by employing complexity theory, based on customers’ online shopping experience and online shopping motivations. To address its objectives, a conceptual model is proposed along with research propositions. The research propositions are validated through a survey on 401 customers’ experience with online shopping, by using the data analysis tool fsQCA (fuzzy-set Qualitative Comparative Analysis). The results, indicate nine configurations of online shopping experience and online shopping motivations that lead to high purchase intentions. This study takes a step further the literature of online shopping and the theoretical ground of how customers’ online shopping experience combines with their online shopping motivations in order to predict and explain increased intention to purchase. The findings offer implications for both researchers and online retailers, regarding the development of new theories in personalized e-commerce and the provision of personalized services.